WBBSE 9th Class Science Solutions Life Science & Environment Chapter – 3 Physiological Processes of Life

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West Bengal Board 9th Class Science Solutions Life Science & Environment Chapter – 3 Physiological Processes of Life

WBBSE 9th Class Life Science & Environment Solutions

TOPIC – 1

PLANT PHYSIOLOGY

SUB-TOPIC – 1.1

PHOTOSYNTHESIS

SUMMARY

Plant physiology is a field of botany, that deals with the physiological functioning of plants. Several fundamental processes such as, photosynthesis, mineral nutrition, transpiration, transportation etc. are included within plant physiology.
Mode of nutrition in higher green plants is autotrophic and plants meet this need of nutrition by the process of photosynthesis.
The term photosynthesis was introduced by Charles Barnes in the year 1893. The word ‘photosynthesis’ is derived from the Greek word ‘photos means light and ‘synthesis means building up.
Mesophyll tissue in the leaf is the site for photosynthesis. Other green parts of plants which contain chlorophyll are also capable of performimg photosynthesis.
Basic components necessary for photosynthesis are CO₂, water, sunlight and photosynthetic pigments. Chlorophyll molecules and the other accessory pigments, like-carotenes and xanthophylls, absorb light energy and then transfer it to the reaction centre. ADP, NADP and RuBP are some organic substances which play important role in photosynthesis.
The whole process of photosynthesis involves two distinct phases, viz., light-dependent reaction or simply light reaction (photochemical phase) and light-independent reaction or simply dark reaction (biosynthetic phase).
Chlorophyll gets energised after getting hit by photon particles of sunlight. This chlorophyll now helps in dissociation of water. Carbon atom of CO₂ is assimilated within the cell as organic compounds.
Glucose is the end product of photosynthesis. It is synthesised in cytosol of mesophyll cells.
Trapping and transformation of solar energy, synthesis of food for the entire living world and maintaining balance between O₂ and CO₂ in environment are the significances of photosynthesis.

Long Answer Type Questions

1. Mention the source and role of the basic raw materials of photosynthesis.

Ans. Source and role of basic raw materials of photosynthesis

Features	Source	Function
1. CO₂ (Carbon dioxide)	Terrestrial plants absorb CO₂ from the air by stomata; aquatic plants absorb CO₂ remain dissolved in water	Is reduced to form glucose which acts as building blocks for other organic molecules
2. H₂O (Water)	Terrestrial plants absorb H₂O from the soil by the roots; aquatic plants absorb it directly from the surroundings	Water molecule splits (photolysis) into H⁺ and OH-ion by activated chlorophyll; from OHions, oxygen is formed and is liberated out
3. Light	Plants obtain from the sun in the form of photon particles	Sunlight supplies solar energy to initiate the process of photosynthesis by activating chlorophyll molecules
4. Chlorophyll	Found in the discs of thylakoids of grana present in chloroplasts of mesophyll tissues of leaves	Capture the photon or quantum of solar energy and converts it to chemical energy; activated chlorophyll (Chl*) hydrolyses water into H⁺ and OH^– ions and thereby helps in the formation of H₂O and O₂

2. Write the role of chlorophyll in photosynthesis. How is photosynthesis related to the flow of energy in the environment?

Ans. Role of chlorophyll in photosynthesis

Chlorophyll gets excited by the absorption of photon particles of sunlight and dissociates the water absorbed by the root hairs into H⁺ and OH^– ions. Chlorophyll also converts the solar energy into the chemical energy which is stored within ATP in the form of potential energy.

Relation of photosynthesis with energy flow in the environment

The green plants trap solar energy and store it within ATP in the form of chemical energy during initial phase of photosynthesis. Later, this energy is converted to potential energy and remains stored within glucose, which is the end product of photosynthesis. On the other hand, a large part of potential energy, stored in glucose, is used up for performing various metabolic activities and is released as heat energy. The remaining potential energy enters the body of the primary consumers (herbivores), then secondary consumers carnivores. In this way, the energy reaches the ultimate consumers. Decomposers, like various bacteria, fungi, etc. act on the dead bodies of these consumers and the energy, thus, is recycled back into the environment through their decomposing activities. Thus, the solar energy returns to the environment after passing through producers and various consumers and decomposers. In this way, photosynthesis is related with energy flow in the environment.

3. Write the significance of light-dependent phase of photosynthesis. What is the significance of light-independent phase of photosynthesis?

Ans. Significance of light-dependent phase of photosynthesis

[1] During photophosphorylation of the light-dependent phase, solar energy is converted into chemical energy and is stored as ATP. [2] ATP, produced during photophosphorylation and NADPH+H⁺, produced during reduction of NADP⁺, in the light-dependent phase, help in the reduction of PGA to PGAld, later in the light-independent phase. [3] During Hill reaction, water gets dissociated to liberate oxygen. This oxygen helps in respiration of all living organisms as well as in combustion.

Significance of light-independent phase of photosynthesis

[1] Solar energy gets stored in glucose as potential energy. This energy helps the living world, directly or indirectly, to perform all metabolic activities. [2] The CO₂ released into the environment by all organisms during respiration, is taken up by plants during the light-independent phase. As a result, the balance of CO₂ and O₂ is maintained in the environment. [3] During this phase, assimilation of carbon takes place and carbohydrate, in the form of glucose, is produced as an end product. This glucose, either directly or indirectly, is the source of food for all heterotrophic living organisms.

4. What are the significance of photosynthesis?

Ans. Significance of photosynthesis

Trapping and transformation of solar energy: Solar energy from the sun is trapped by chlorophyll and transformed into chemical potential energy in the glucose molecule. This energy is then passed on from the producers (plants) to the consumers through food chain and is liberated during respiration.
Source of food: Through the process of photosynthesis, inorganic materials like water and CO₂ combine to produce organic molecule glucose, which is the basic component of all food matters on earth. Not only plants, but other animals also obtain this food, either directly or indirectly, to survive.
3 Maintainance of 0₂ and CO₂ balance in the environment: During respiration, all living organisms release CO₂ and absorb O₂. On the other hand, green plants release O₂ and absorb CO₂ during photosynthesis. Thus, photosynthesis in combination with respiration, helps to maintain the balance between O₂ and CO₂ in the environment.
Source of fuel: Due to natural disasters, like earthquake, plants get trapped under the soil and in due course of time get converted into coal and mineral oils. The energy obtained from these coal and mineral oils, originally is the solar energy which was entrapped by the plants in the past. This . is how photosynthesis is the only source of different types of fuel.
Source of human welfare: We get different types of important materials from plants, like food, wood, paper, cloth, rubber, gum, paint, etc. Apart from these, we get different alkaloids like morphine, quinine, reserpine, etc. and various medicines from plants. Therefore, plants, more specifically photosynthesis, is very important physiological process for human welfare.

Short Answer Type Questions

1. Mention the components, necessary for photosynthesis.

Ans. The materials required for photosynthesis are as follows-[1] Raw material-Water and carbon dioxide, [2] Pigments-Chlorophyll and carotenoids (carotene and xanthophyll), [3] Energy-Light (sunlight or bright artificial light).

2. Where does photosynthesis occur?

Ans. Photosynthesis occurs in the chloroplastcontaining parenchyma (chlorenchyma) tissues known as mesophyll tissue of higher green plants. These tissues are distributed in leaves and all other tender, green parts of the plants, like stems (in herbs), sepals of flowers, petals (water lily and custard apple flower), bracts (Adhatoda sp.), stipule (pea plant), root (orchid, Tinospora), etc.

3. How do plants absorb water for photosynthesis?

Ans. Terrestrial plants absorb water from the soil with the help of their roothairs. Aquatic plants absorb water from the surrounding water medium through their body surface by the process of simple diffusion. Epiphytes (plants growing on other plants) like orchids, have special spongy tissue called velamen, in their aerial roots. This roots with thick hygroscopic outer coating of velamen absorb rain water and moisture from air to fulfill the need of water.

4. Define photosynthesis.

Ans. Photosynthesis is a photochemical process in which green plants and certain chlorophyllcontaining organisms utilise water and carbon dioxide as raw materials to synthesise monosaccharide (glucose) in their body by entrapping light energy (especially sunlight) within it and releasing oxygen in the environment as a byproduct.

5. How do plants absorb CO₂ for photosynthesis?

Ans. All terrestrial plants absorb CO₂ from the atmosphere through stomata on the leaves. Aquatic plants absorb dissolved CO₂ from surrounding water by simple diffusion through body surface. Partially submerged plants absorb CO₂ through stomata on their aerial portion of the body and the submerged portion get CO₂ by diffusion from the surrounding water medium.

6. What do photosynthetic pigments in plants do?

Ans. In plants, there are two types of photosynthetic pigments, namely, chlorophyll and carotenoids. Chlorophyll helps in the dissociation of water and formation of energy packed ATP molecules. Carotenoids (carotene and xanthophyll) entrap light energy and transfer it to the reaction centre of chlorophylls for further proceedings.

7. Why photosynthesis is known as an anabolic process?

Ans. In photosynthesis, new substance (glucose) is produced from raw materials (CO₂, H₂O, lights) and due to this dry weight of plant cell’s protoplasm is increased and energy is also stored as potential energy. For all these reasons, photosynthesis is termed as an anabolic process.

8. Why photosynthesis is called oxidation-reduction reaction?

Ans. Photosynthesis involves the reduction of carbon dioxide into sugars and the oxidation of water into molecular oxygen. That is why photosynthesis is also called as oxidation-reduction reaction.

9. Why photosynthesis does not occur in plant root? Name one exceptional plant.

Ans. Reason: Photosynthesis occurs in chloroplasts which is absent in roots. Moreover, light can’t reach root because of its underground position. For all these reasons, most of the plant root can’t do photosynthesis.

Exception: Roots of Gulancha, Tinospora and Trapa.

10. What is meant by mesophyll tissue? Write its by significance.

Ans. Mesophyll tissue: Mesophyll is the internal ground tissue located between the two epidermal cell layers of the leaf and is mostly composed of two kinds of chloroplast containing tissues which are responsible for performing photosynthesis. These tissues are the palisade parenchyma which is present on the upper side of leaf, is made up of elongated chlorenchyma cells and the spongy paranchyma which is found on the lower side of leaf, is made up of spherical or ovoid cells.

Significance: The most important role of the mesophyll cells is to perform photosynthesis. Mesophyll cells provide large intercellular spaces which allow carbon dioxide to move freely within the leaf.

Very Short Answer Type Questions

Multiple Choice Questions & Answers [MCQ]

1. Which of the following is/are plant physiological process/processes?

A. Respiration

B. Transpiration

C. Photosynthesis

D. All of these

Ans. D

2. Which of the following components is/are necessary for photosynthesis?

A. Light and chlorophyll

B. Carbon dioxide

C. Water

D. All of these

Ans. D

3. The gas released during photosynthesis is –

A. Oxygen

B. Carbon dioxide

C. Both A and B

D. None of these

Ans. A

4. The type of tissue, which serves as the site of photosynthesis, is-

A. Meristematic tissue

B. Mesophyll tissue

C. Epidermal tissue

D. Vascular tissue

Ans. B

5. The main end product of photosynthesis is-

A. Glucose

B. Starch

C. Fructose

D. Glycogen

Ans. A

6. During photosynthesis, terrestrial plants absorb this gas from atmosphere. Which gas is it?

A. H₂O

B. CO₂

C. O₂

D. None of these

Ans. B

7. Aquatic plants absorb CO₂ through-

A. Stomata

B. Root hair

C. Body surface

D. Leaves

Ans. C

8. In plants, stomata help in-

A. Absorption of CO₂ and O₂

B. Exchange of CO₂ and O₂ and release of extra water as vapour

C. Intake of CO₂ and release of extra water as vapour

D. None of these

Ans. B

9. The cell organelle in plants, acting as the site of photosynthetic reactions, is-

A. Chloroplast

B. Chromoplast

C. Leucoplast

D. Mitochondrion

Ans. A

10. In flowering green plants, photosynthe occurs in-

A. Leaves only

B. Leaves, sepals, green fruit skin and tender stems

C. Leaves, stems and roots

D. Leaves and tender stems

Ans. B

11. Select the correct statement-

A. Light reactions of photosynthesis occur in the presence of sunlight

B. Photosynthesis can take place only under sunlight

C. Dark reaction is hindered in the presence of sunlight

D. Glucose is produced as a byproduct in light reaction

Ans. A

12. The only metallic element present in chlorophyll is-

A. Carbon

B. Copper

C. Iron

D. Magnesium

Ans. D

13. Source of oxygen, released during photosynthesis, is-

A. CO₂

B. H₂O

C. Both A and B

D. None of these

Ans. B

14. The colour of light preferable for maximum rate of photosynthesis, is-

A. Green light

B. Blue light

C. Yellow light

D. Red light

Ans. D

15. Photosynthesis occurs at its best under-

A. High oxygen concentration

B. Low carbon dioxide concentration

C. High carbon dioxide concentration under red light

D. Low oxygen concentration under green light

Ans. C

Answer in a single word or sentence

1. Name the scientist who coined the term ‘photosynthesis’.

Ans. Barnes coined the term ‘photosynthesis’.

2. Name a vascular land plant, which photosynthesises through its roots.

Ans. Stylites andicola is a vascular land plant, which photosynthesises through its roots.

3. What does NADP stand for?

Ans. NADP stands for Nicotinamide Adenine Dinucleotide Phosphate.

4. From which of the raw materials does glucose get its oxygen during photosynthesis?

Ans. Glucose, the end product of photosynthesis, gets its oxygen from CO₂,

5. Which element is taken up by green plants from environment in the form of an oxide?

Ans. Carbon is absorbed by green plants from the environment in the form of an oxide, viz. carbon dioxide.

6. Which biocatalyst is essential for photosynthesis?

Ans. Chlorophyll is the biocatalyst, which is essential for photosynthesis.

7. Which pigments are necessary for photosynthesis, other than chlorophyll?

Ans. Other than chlorophyll, carotenoids are the ‘pigments which are necessary for photosynthesis.

8. Name two members under kingdom Protista, which are capable of synthesising their own food by photosynthesis.

Ans. Euglena sp. and Chrysamoeba sp. are the two members under kingdom Protista, which are capable of synthesising their own food by photosynthesis.

9. Name an enzyme, necessary for the assimilation of carbon during the lightindependent phase of photosynthesis.

Ans. The enzyme RuBisCO is necessary for the assimilation of carbon during the lightindependent phase of photosynthesis.

10. What is the full form of the enzyme RuBisCO?

Ans. The full form of RuBisCO is Ribulose Bisphosphate Carboxylase Oxygenase.

11. Which of the raw materials of photosynthesis is oxidised during the process?

Ans. Water molecule is oxidised during the process of photosynthesis.

12. Which of the raw materials of photosynthesis is reduced during the process?

Ans. Carbon dioxide is reduced during photosynthesis.

13. Where do plants generally store their food?

Ans. Plants generally store their food in roots, stems and fruits.

14. What are the end products of photosynthesis?

Ans. Glucose, oxygen and water are the end products of photosynthesis.

15. Who discovered that oxygen, evolved during photosynthesis, comes from water?

Ans. British scientist Robin Hill discovered that oxygen, evolved during photosynthesis, comes from water.

16. Who discovered the reaction path of carbon assimilation?

Ans. Scientist Blackmannn discovered the reaction path of carbon assimilation.

17. Who discovered the reaction path of glucose synthesis and regeneration of RuBP from PGA?

Ans. Scientist Melvin Calvin and his co-workers discovered the cyclic reaction path of glucose synthesis and regeneration of RuBP from PGA.

18. Which co-enzyme carries hydrogen for the reduction of PGA?

Ans. NADP carries hydrogen for the reduction of PGA.

19. Which compound supplies chemical energy for the reduction of PGA?

Ans. Adenosine triphosphate (ATP) supplies chemical energy for the reduction of PGA.

19. Out of 12 PGAId molecules, how many take part in the synthesis of RuBP in Calvin cycle?

Ans. Out of 12 PGAld molecules, 10 molecules take part in the synthesis of RuBP in Calvin cycle.

20. Which are the end products of light-dependent phase of photosynthesis?

Ans. Oxygen, ATP and NADPH + H⁺ are the end products of light-dependent phase of photosynthesis.

21. Which of the end products of light-dependent phase take part in the reactions of lightindependent phase of photosynthesis?

Ans. ATP and NADPH + H⁺ are the end products of light-dependent phase, which take part in the reactions of light-independent phase of photosynthesis.

22. Which instrument is used to neasure the absorption spectrum of chlorophyll?

Ans. The absorption spectrum of chlorophyll is measured with the help of spectrophotometer.

23. Due to excessive heat from the sun, the process of photosynthesis stops. What is this condition called?

Ans. The condition, in which the process of photosynthesis stops due to excessive heat from the sun, is called solarisation. ***

24. Under what temperature does photosynthesis occur at its best?

Ans. Photosynthesis occurs at its best at an optimum temperature ranging between 25°C-35°C.

25. Name a bacteria which can prepare its own food without performing photosynthesis.

Ans. Thiobacillus sp. is a bacteria which can prepare its own food without performing photosynthesis.

26. In green plants, what percentage of the total stored water is used during photosynthesis?

Ans. During photosynthesis, only 1% of the total stored water is used up by green plants.

27. What is the absorption spectrum of carotenoid?

Ans. Absorption spectrum of carotenoid is bluegreen.

28. Why photosynthesis does not occur in animal cells?

Ans. Photosynthesis does not occur in animal cells because they lack chloroplast and hence the photosynthetic pigment chlorophyll.

29. Which compound is both a raw material and a byproduct, in the process of photosynthesis?

Ans. Water is both a raw material as well as a byproduct, in the process of photosynthesis.

30. Give an example of a natural and an artificial Hill reagent?

Ans. An example of natural Hill reagent is NADP, and an example of artificial Hill reagent is potassium ferric oxalate.

Fill in the blanks

1. ………… is the photosynthetic tissue of green plants.

Ans. Chlorenchyma/ Mesophyll

2. Reactions of light-independent phase occur in ……….. of chloroplast.

Ans. Stroma

3. Scientist ……….. proved that photosynthetic reactions occur in two phases.

Ans. Blackmann

4. ……….. is considered as the energy currency of the cells.

Ans. ATP

5. In plant cell, starch is stored in ……….

Ans. Leucoplast

6. Green plants absorb ……… gas to synthesise glucose during photosynthesis.

Ans. Carbon dioxide

7. ………. is a cellular compound which reacts with atmospheric CO₂ to produce phosphoglyceric acid.

Ans. RuBP

8. ………. is the enzyme which is necessary for the synthesis of PGA in the light-independent phase.

Ans. RuBisCO

9. Photosynthesis is a ………. process.

Ans. Anabolic

10. In photosynthesis, water is oxidised and ……… is reduced to carbohydrates.

Ans. CO₂

State True or False

1. Aquatic plants absorb CO₂ from water through root hair.

Ans. False

2. ATP stands for Adenosine Tri Phenol.

Ans. False

3. Blue-green algae like Nostoc, Anabaena, etc. can synthesise their own food.

Ans. True

4. Ionisation of water is known as Blackmann’s reaction,

Ans. False

5. NADP is an artificial Hill reagent.

Ans. False

6. Out of 12 PGAld molecules, only 2 take part in glucose synthesis.

Ans. True

7. RuBisCO is used in the light-dependent phase of photosynthesis.

Ans. False

8. Photosynthesis stops due to excessive heat from the sun.

Ans. True

9. Light-independent phase of photosynthesis is also known as Blackmann’s reaction.

Ans. True

SUB-TOPIC – 1.2

MINERAL NUTRITION

SUMMARY

The inorganic materials obtained mainly from soil that are used as raw materials by plants are called mineral nutrients. Plant collect a large quantity of mineral nutrients from three different sources, viz., soil, water and atmosphere. However, only 20 elements are essential for normal plant growth and metabolism. The process of nutrition by which mineral nutrients are absorbed from environment, are distributed and are used in metabolic activities of plant, is called as mineral nutrition.
The mineral elements those act as important structural and physical components are known as essential elements, eg.-N, P, K, Ca, Mg, S, etc.
Macroelements are required in large quantities, whereas, microelements are required in less. ny amount for proper growth, development, structure aand metabolic activities of plant.
Inadequate supply of any one of the essential elements leads to deficiency symptoms in plant bodies which may even lead to plant death.
Mineral nutrients help in synthesis of enzymes (as cofactor), act as electron carrier for redox reaction. Moreover, these elements maintain water balance in plants, help in chlorophyll synthesis and control buffer action.

Long Answer Type Questions

1. Write the characteristic features of macronutrients and micronutrients.

Ans. Characteristic features of macronutrients

[1] These elements are present in larger quantities (1-10 mg per g dry weight of plants, or more). [2] They are mainly involved in the synthesis of structural components of the plant cells. [3] They also participate in maintaining the osmotic potential of the plants.

Characteristic features of micronutrients

[1] The elements are present in minute quantities (0.1 mg per g dry weight of plant or less). [2] High concentration of micronutrients may prove to be toxic for the plants. [3] They mainly participate in electron transport mechanism and act as cofactors for various enzymes.

2. Mention the importance of any macronutrients in plants.

Ans. Importance of any five macronutrients in plants*

Carbon (C): [A] It is the basic constituent of protoplasm. [B] It plays the role of chief component for the synthesis of carbohydrate, protein, fat, enzymes, vitamins, etc.
Hydrogen (H): [A] It is the basic constituent of protoplasm. [B] It is needed for the synthesis of carbohydrate, protein and fat.
Oxygen (0): [A] It helps in the synthesis and oxidation of food. [B] It is needed for normal functioning metabolic activities. [C] It is needed for the synthesis of carbohydrate, protein and fat.
Nitrogen (N): [A] It is the chief ingredient of protein. [B] It helps in building cellular structure, proper growth and development of body. [C] It is needed for the synthesis of chlorophyll.
Phosphorus (P): [A] It plays an important role in protein synthesis. [B] It acts as a component of ATP, NADP and membrane of cells and other organelles. [C] It prevents premature shedding of leaves, blackening of fruits and leaves.
Sulphur (S): [A] It is the major constituent of certain amino acids, vitamins and co-enzyme A. [B] It helps in the formation of chlorophyll and development of roots. [C] It also prevents hardening of stems and plays important role in growth and metabolism.
Potassium (K): [A] It takes part in protein and carbohydrate synthesis, [B] It acts as co-enzyme and helps in the stomatal movement. [C] Potassium maintains normal growth and colour of leaves.
Calcium (Ca): [A] It helps in cell division by spindle formation. [B] It helps in nitrogen and carbohydrate metabolism. [C] It helps in formation of cell membrane and the middle lamella of cell wall in plants. [D] It maintains normal blooming of flowers.
Magnesium (Mg): [A] It acts as primary metallic constituent of chlorophyll. [B] It helps in enzyme activation. [C] It prevents scorching and discolouration of leaves. [D] It helps in nucleic acid synthesis and controls fat and carbohydrate metabolism.

3. Mention the deficiency symptoms of the macronutrients phosphorus, sulphur and magnesium in plants. Mention the deficiency symptoms of the micronutrients copper, manganese and boron in plants.

Ans. Symptoms due to deficiency of P, S and Mg

Phosphorus (P): [A] Leaves and stems turn bluish-green in colour. [B] Necrosis occurs in leaves. [C] Plants become weak and stunted.
Sulphur (S): [A] Curling of leaves occurs followed by necrosis. [B] Nodule formation in leguminous plants is hampered. [C] Overall growth of plant is hampered.
Magnesium (Mg): [A] Chlorosis of matured leaves occurs. [B] Retarded growth of plants is seen. [C] Carbohydrate formation is hampered.

Symptoms due to deficiency of Cu, Mn and B

Copper (Cu): [A] Necrosis occurs in tender leaves. [B] Nitrogen metabolism is hampered. [C] Dieback disease (rotting) occurs in the tender portions of stems.
Manganese (Mn): [A] Necrosis of leaves occurs. [B] Leaves become yellowish and intervenous chlorosis takes place.
Boron (B): [A] Rotting of apical portions of stems and roots, followed by necrosis. [B] Margins of leaves dry up and as a result the leaves curl up. [C] Drought spot disease occurs in apples.

4. Mention the importance of different micronutrients in plants.

Ans. Importance of different micronutrients in plants*

Iron (Fe): [A] It helps in the formation of chlorophyll and chromatin reticulum. [B] It acts as structural element of electron carriers and helps in ion absorption.
Copper (Cu): [A] It acts as structural component of some enzymes and helps in reduction of nitrates. [B] It takes part in electron transportation in photosynthesis. [C] It prevents necrosis of leaves in cereals and pulses.
Molybdenum (Mo): [A] It helps in the fixation and assimilation of nitrogen. [B] It acts as cofactor for enzymes involved in nitrogen fixation. [C] It helps in normal flowering and colouration of leaves. [D] It also helps in protein synthesis.
Zinc (Zn): [A] It helps in the synthesis of auxins and certain proteins, [B] It activates various enzymes by acting as cofactor. [C] It also maintains normal growth of the stems and roots.
Manganese (Mn): [A] It acts as enzyme activator. [B] It takes part in chlorophyll and protein synthesis. [C] It helps in the normal growth of shoots and prevents necrosis of leaves.
Boron (B): [A] It helps in the formation and growth of flowers and leaves. [B] It takes part in protein synthesis. [C] Boron helps in the metabolism of calcium and potassium. [D] It also helps in the elongation of pollen tube.
Chlorine (CI): [A] Chloride ions, in the cell sap, helps in maintaining the osmotic balance of the cell. [B] It helps in the opening and closing of stomata. [C] It plays a passive role in photosynthesis.
Nickel (Ni): [A] Nickel is a component of some plant enzymes, most notably urease, which metabolises urea into ammonia. [B] It also acts as a catalyst of enzymes, that help legumes to fix nitrogen.

Short Answer Type Questions

1. What is meant by macronutrients?

Ans. The elements, that are required in larger quantities for growth, development and normal physiological activities of plants, are called macronutrients. Example-Carbon (C), Nitrogen (N), Phosphorus (P), etc.

2. What is meant by micronutrients?

Ans. The elements, that are required in minute quantities for normal physiological activities of plants, are called micronutrients. ExampleMolybdenum (Mo), Boron (B), Zinc (Zn), etc.

3. How are mineral nutrients associated with survival of plants?

Ans. For normal growth, proper formation of cells and tissues and proper operation of all physiological functions, plants need different minerals. Minerals act as structural components of protoplasm, cofactors of various enzymes controlling several biochemical reactions within the cells, etc. That is how mineral nutrients are associated with the survival of plants.

4. How do different elements take part in the formation of a plant cell?

Ans. Various elements, such as C, H, O, S, Mg, P, N and Fe, play a prominent role in the formation of protoplasmic chemical constituents of a cell. All cellular matters are basically composed of carbon (C), hydrogen (H), oxygen (O), and nitrogen (N). Proteins need sulphur (S), nucleic acids need phosphorus (P), chlorophylls need magnesium (Mg) and middle lamella of cell needs calcium (Ca) other than C, H, O, and N.

5. What are the symptoms that occur due to the deficiency of potassium?

Ans. The distinct symptoms that occur due to the deficiency of potassium aree-[1] discoloration of leaves, [2] slow growth of roots and seeds, [3] curling of older leaves.

6. What are the symptoms that occur due to that occur due to deficiency of zinc?

Ans. The distinct symptoms that occur due to deficiency of zinc are- [1] retarded growth of roots, stems and leaves, [2] delayed seed formation, [3] discolouration of leaves.

7. What is necrosis?

Ans. When specific zones, like-tips, margins and areas between the veins become discoloured due to deficiency of any particular mineral nutrient (viz.-Cl, Mn, Cu) resulting drying up and cell death, then the situation is called necrosis.

8. Name the metallic elements which are essential for plants.

Ans. The metallic elements which are essential for plants are-Magnesium (Mg), Potassium (K), Calcium (Ca), Manganese (Mn), Iron (Fe), Zinc (Zn), Copper (Cu), Molybdenum (Mo), Cobalt (Co), Nickel (Ni), Sodium (Na), etc.

9. Write the source of carbon (C), oxygen (0) and hydrogen (H) in plants.

Ans. In plant body, source of carbon is the CO, gas, present in atmosphere. Hydrogen is obtained from the water vapour present in atmosphere and also from the water present in soil. Oxygen is taken up by plants directly from the air.

10. What is chlorosis?

Ans. The yellowing of leaf-tissue due to deformed chlorophyll or destruction of chlorophyll caused by high alkalinity or nutrient deficiency is called chlorosis. This deficiency syndrome occurs due to lack of N, K, Mg, S, Fe, Mn, Zn and Mo.

11. Define mottling and wilting.

Ans. Mottling: Different patterns of irregular marks, spots, streaks, blotches or patches of different shades of colour because of anthocyanin pigmentation when appear on leaves due to nutrient deficiency, is called mottling.

Wilting: Wilting is the loss ofturgour pressure of nonlignified plant cells causing drooping of plant parts, like leaves, branches, due to nutrient deficiency.

Very Short Answer Type Questions

Multiple Choice Questions & Answers [MCQ]

1. Which of the elements comprise the maximum mass of our body?

A. Oxygen

B. Nitrogen

C. Carbon

D. Hydrogen

Ans. C

2. The mineral nutrients, which are very important for normal growth and development of plants, are called

A. Non-essential macronutrients

B. Essential micronutrients

C. Essential elements

D. None of these

Ans. C

3. The essential elements for a plant are those, which

A. Are necessary in large quantities

B. Are not replacable by any other element

C. Are taken from the atmosphere

D. Are necessary for structural purposes only

Ans. B

4. The mineral nutrients, required in large quantities for normal growth, development and physiological functions of plants, are called-

A. Macronutrients

B. Micronutrients

C. Essential nutrients

D. None of these

Ans. A

5. A nutrient whose deficiency causes chlorosis(yellowing of leaves), is-

A. Molybdenum

B. Copper

C. Magnesium

D. Boron

Ans. C

6. Which of the following options comprises macronutrients only?

A. C, Ca, Mg, Mn

B. C, N, Cu, P

C. N, P, Mg, Ca

D. Mg, K, P, B

Ans. C

7. Which of the following options comprises microelements only?

A. B, Cu, Mn, Zn

B. C, H, Cl, P

C. N, P, S, Ca

D. H, O, P, Ca

Ans. A

8. Essentiality of macronutrients for the normal growth, development and physiological functions of plants is-

A. More than 100 mg/g dry weight

B. About 100 mg/g dry weight

C. About 1-10 mg/g dry weight

D. Less than 1 mg/g dry weight

Ans. C

9. Premature shedding of leaves and blackening of fruits occur due to the deficiency of-

A. Nitrogen

B. Magnesium

C. Iron

D. Phosphorus

Ans. D

10. Growth of plants severely retards in the deficiency of-

A. Nitrogen

B. Phosphorus

C. Sulphur

D. Calcium

Ans. A

Answer in a single word or sentence

1. Which type of nutrients mainly take part in the structural formation of protoplasm?

Ans. Macronutrients take part mainly in the structural formation of protoplasm.

2. Which type of elements act mainly as cofactors of enzymes?

Ans. Microelements mainly act as cofactors of enzymes.

3. What is the functional similarity between Fe and Cu in the life process of an organism?

Ans. Both Fe and Cu take part in oxidationreduction process of photosynthesis and respiration.

4. What is the functional similarity between Zn and Mg in biochemical activities?

Ans. Both Zn and Mg act as cofactors of enzymes.

5. Which metallic element is actively present in electron carriers like cytochrome and ferredoxin?

Ans. Iron (Fe) is actively present in electron carriers like cytochrome and ferredoxin.

6. Mention a deficiency symptom of sulphur in plants.

Ans. In case of sulphur deficiency, young twigs become weak.

7. Mention one metallic macronutrient and one micronutrient, essential for plants.

Ans. Magnesium is a metallic macronutrient and iron is a metallic micronutrient, essential for plants.

8. Name any two gaseous macroelements essential for all living organisms.

Ans. Oxygen and nitrogen are two gaseous macroelements essential for all living organisms.

9. Which macroelements take part in the structural formation of protoplasm?

Ans. The macroelements which take part in the structural formation of protoplasm are C, H, O, N, P, Mg and Ş.

10. Which macronutrient is essential for the formation of plasma membrane?

Ans. Calcium is an essential macronutrient which helps in the formation of plasma membrane.

Fill in the blanks

1. Fruit cracking appears mainly due to the deficiency of …………..

Ans. Calcium

2. Most plants receive nitrogen from the soil, in the form of …………..

Ans. Nitrates

3. ………….. are essential in larger quantities for the proper health of plants.

Ans. Macronutrients

4. ……….. show indistinct deficiency symptoms.

Ans. Micronutrients

5. Presence of inorganic salts in the cell sap are involved in maintaining the ……… balance of cell.

Ans. Micronutrient

6. Nickel is an example of ……….

Ans. Osmotic

7. Phosphates and carbonates act as …….. and thus resist marked change in pH.

Ans. Buffers

8. …………. concentration of micronutrients may prove to be toxic.

Ans. High

9. Dead spots is observed due to deficiency of …………

Ans. Zinc

10. Drought spot of apples is caused by the deficiency of ……….

Ans. Boron

State True or False

1. Due to the deficiency of phosphorus, leaves and stems turn bluish-green in colour.

Ans. True

2. The metallic component of chlorophyll is zinc.

Ans. False

3. Iron is an enzyme activator.

Ans. True

4. There are 9 macronutrients, which are essential for plants.

Ans. True

5. Magnesium is the metallic component of anthocyanin.

Ans. False

6. Sulphur is an important constituent of coenzyme A.

Ans. True

7. Chlorosis develops due to nitrogen and sulphur deficiency.

Ans. True

8. Whiptail disease of cauliflower is caused by the deficiency of molybdenum.

Ans. True

9. K⁺ ions involve in stomatal regulation.

Ans. True

10. The main component of chlorophyll is C, H, O, N and Mg.

Ans. True

SUB-TOPIC – 1.3

TRANSPIRATION

SUMMARY

Transpiration is a physiological process by which the excess water drawn by the roots of plants is eliminated in form of water vapour through the aerial parts of plants, especially leaves.
In both the process of evaporation and transpiration, water is evaporated from the surface to the atmosphere in the form of a water vapour. But both the processes are different from each other. Evaporation is a physical process whereas transpiration is a biological process.
Stomata are the primary site of transpiration. Though cuticles and lenticels, present on stems, also take part in transpiration.
Stomata are small openings, present on leaf surfaces, that are bordered with guard cells. Stomata take active part in transpiration and gaseous exchange in plant body.
Transpiration is affected by several internal and external factors. The external factors are temperature, humidity, wind speed, light intensity etc. and the internal factors are leaf area, structural peculiarities of leaf, stomatal density etc.
Transpiration provides the plant with evaporative cooling, nutrient flow, carbon dioxide entry and pulling of water from root to tip.
Though transpiration is an inevitable process, excess rate of transpiration leads to wilting, serious desiccation and shortage of water. Because of this reason, transpiration is called ‘necessary evil.
Transpiration rate of plants can be measured by a number of devices like lysimeter, porometer, heat balance sap flow guage, etc.

Long Answer Type Questions

1. Mention one difference between stomata and hydathodes. Give a brief account of different types of a brief account of transpiration of plants.

Ans. Difference between stomata and hydathodes

One difference between stomata and hydathodes is that, stomata usually open during the day and remain closed during the night (in some desert plants, like Aloe vera, it remain closed during the day, and open during the night), whereas, hydathodes remain open all the time. This opening and closing of stomata can be controlled by the guard cells, but there are no such mechanism to close hydathodes.

Different types of transpiration

Transpiration occurs through three different parts of plant body-stomata, lenticels and cuticle. Based on this, the process is divided into the following types.

Stomatal transpiration: Stomata are small pores, present mainly on leaves and a few other parts of plants. Each of these pores is surrounded by two guard cells, that help to open and close the stomatal pores subsequently during the day and at night. Maximum amount of excess water (about 90-97%) is eliminated from the plant body through the stomata.
Cuticular transpiration: Cuticle is a layer of waxy coating present on the epidermis of leaves. Very little amout of water (about 3-10%) is eliminated through the minute pores of the cuticle.
Lenticular transpiration: Lenticels are permanent, lens-shaped, minute pores, found on the cracked bark of the trees. Negligible amount of water (about 0.1%) is transpired through these pores.

2. Mention the on the roles of different external factors regulating the rate of transpiration.

Ans. External factors regulating transpiration

Various external factors control the rate of transpiration. These are discussed below.

Intensity of light: The most important external factor which regulates the rate of transpiration is the intensity of light. In nature, stomata open during daytime in the presence of sunlight and close at night. Thus, light controls transpiration by regulating the opening and closing of stomata. Increase in the intensity of light, increases the rate of transpiration and decrease in light intensity decreases the rate of transpiration.
Temperature: Rate of transpiration increases with the rise in temperature. But when temperature rises above 35°C, the stomata start to close, in order to prevent excess water loss.
Humidity: Increase in relative humidity decreases the rate of transpiration and vice versa. That means, transpiration is inversely proportional to the relative humidity.
Flow of wind: In airy environment, transpiration occurs at a faster rate. Therefore, flow of wind is directly proportional to the rate of transpiration.
Density of carbon dioxide: Rate of transpiration also depends on the density of CO₂ in the atmosphere. When density of CO₂ increases in atmosphere to a certain extent, as well as, more CO₂ accumulates in leaves, stomatal pores close, and rate of transpiration decreases. Similarly, when density of CO₂ is less, rate of transpiration increases. Thus, density of CO₂ in the atmosphere is inversely proportional to the rate of transpiration.

3. Mention the roles of different internal factors regulating the rate of transpiration.

Ans. Internal factors regulating transpiration

Various internal factors control the process of transpiration. These are discussed below.

Surface area and number of stomata in the leaves: Leaves with larger surface area possess more number of stomata. Therefore, transpiration rate is higher in plants with broader and larger leaves.
Size of stomata: Size of stomata is directly proportional to the rate of transpiration of a plant.
Position of stomata: Stomata, present on the surface of leaves, facilitate transpiration, but in some plants, stomata is slightly sunken below the surface of leaves. This type of stomata helps to reduce the rate of transpiration.
Cuticle: A plant with thick and waxy cuticle reduces cuticular transpiration. On the other hand, a thin and porous cuticle enhances transpiration rate.
Age of leaves: As the leaves grow older stomata get clogged which lessens the rate of transpiration. So age of leaves is inversely proportional to the rate of transpiration.
Protoplasm: Increased density of cellular protoplasm results in an increase in the rate of transpiration and vice versa. Thus, density of protoplasm in the cell is directly proportional to the rate of transpiration.
Presence of hormones: Hormones, such as abscisic acid, control the rate of transpiration by regulating the opening and closing of stomata.

4. Explain the beneficial effects of transpiration. Mention its harmful effects.

Ans. Beneficial effects of transpiration

The beneficial effects of transpiration are as follows-

Ascent of sap: Transpiration results in transpiration pull, by which water and minerals reach the top leaves of the trees.
Elimination of excess water: By transpiration, excess water from the plant body is removed. It eases the physiological activities within the cells.
Cooling plant body: By this process, latent heat of evaporation is lost from the plant body, which cools the plant.
Maintaining water balance: Due to the removal of excess water from plant body, water balance is maintained within it..

Harmful effects of transpiration

The harmful effects of transpiration are as follows-

Drying of leaves and twigs: Excess transpiration reduces water content in plant cells. As a result, leaves and other softer parts of plants become dry.
Wilting: In case of excess transpiration, the cells lose turgidity and shrink. Hence, leaves and tender branches droop. This is called wilting. If the whole plant wilts and remains in that state for several hours, it may die.
Wastage of energy: Plant utilises only about 5% of the total absorbed water for various functions of its body. The rest (about 95%) is given out by transpiration. Thus, there is a wastage of energy.
Inhibition of gaseous exchange: Due to excess stomatal transpiration, gaseous exchange during photosynthesis and respiration through stomata, is inhibited.

Short Answer Type Questions

1. What are stomata?

Ans. The tiny openings, present generally on the epidermis of leaves and are surrounded by the guard cells, are called stomata. They help plants in gaseous exchange and transpiration.

2. What is meant by stomatal apparatus?

Ans. The tiny openings on the epidermis of leaves are known as stomata. Stomata, two bean-shaped guard cells) and subsidiary cells (i.e., the specialized epidermal cells surrounding guard cells) together form stomatal apparatus.

3. How do guard cells control the opening and closing of stomata?

Ans. In the presence of light, hygroscopic pressure increases inside the guard cells. Due to unequal thickness and elasticity of cell walls of the two opposite sides of each guard cell, the cells bend like beans. As a result, the space between two guard cells widens and the stomata open. In the absence of light, hygroscopic pressure decreases inside the guard cells and the stomata close.

4. Why is the stomata of lotus plant present on the dorsal surface of the leaves?

Ans. The lotus leaves float on the water surface and the stomata are present on the dorsal surface to keep direct contact with air. This typical placement of stomata helps lotus leaves to maintain gaseous exchange with atmosphere and thus, perform transpiration.

5. Why do plants with wider leaves wilt in summer but a pine tree remains unaffected?

Ans. Plants with wider leaves have more number of stomata, through which they lose excess water in form of vapour due to transpirati days. This loss of water makes the cells flaccid and the protoplasm shrinks. This results into wilting of these plants. Whereas, a pine tree possesses needle-like leaves with very little number of sunken stomata. Therefore, pine trees lose much less water by transpiration and remain unaffected even on a summer day.

6. Why is transpiration called a necessary evil?

Ans. Transpiration helps plants in the ascent of sap, removal of excess water, cooling the plant body, maintaining the water balance. On the other hand, excessive transpiration causes decrease in protoplasmic water content and thus, results in shrinkage of cells followed by wilting of leaves and tender branches. This is why, transpiration is called a necessary evil.

7. If all the leaves of a plant are applied with a layer of vaseline, what will happen to it?

Ans. If all the leaves of a plant are applied with a layer of vaseline, the stomatal openings will be sealed completely. In this situation, gaseous exchange for photosynthesis and respiration will be ceased. The excess water in the plant body will not be released into atmosphere. This will affect many necessary physiological activities of the cells and the cells will die and eventually will the whole plant.

8. How does transpiration control environmental antral environ condition?

Ans. By transpiration, water vapour is released in the atmosphere. This increases the relative humidity, which in turn helps in the formation of clouds. Therefore, transpiration initiates rainfall in an area and thus, regulates atmospheric temperature and soil water content of that environment.

Very Short Answer Type Questions

Multiple Choice Questions & Answers [MCQ]

1. During transpiration, plants release-

A. Water from the body

B. Excess water as vapour

C. Only CO₂

D. Water and CO₂

Ans. B

2. Transpiration occurs through-

A. Stomata of leaves

B. Lenticels of stem

C. Cuticle of leaves

D. All of these

Ans. D

3. Maximum transpiration occurs through-

A. Stomata

B. Cuticle

C. Lenticels

D. Cracks on the plant surface

Ans. A

4. Rate of transpiration is-

A. Inversely proportional to the intensity of light

B. Directly proportional to the humidity of atmosphere

C. Directly proportional to the intensity of light

D. Inversely proportional to the rate of water absorption

Ans. C

5. The scientist who said that “transpiration is a necessary evil”-

A. Curtis

B. Barnes

C. Woodland

D. Calvin

Ans. A

6. Stoma remains guarded by a pair of-

A. Guard cells

B. Companion cells

C. Sclerenchymatous cells

D. Sieve cells

Ans. A

7. Increase in CO₂ concentration in the atmosphere-

A. Increases transpiration

B. Decreases transpiration

C. Has no role in transpiration

D. Stops transpiration

Ans. B

8. Very high temperature (above 35°C)-

A. Increases the rate of transpiration

B. Decreases the rate of transpiration

C. Shows no change in the rate of transpiration

D. Stops transpiration

Ans. B

9. Higher rate of transpiration needs-

A. Sudden gusty wind

B. Continuous hot air flow

C. Steady moist wind flow

D. All of these

Ans. B

Answer in a single word or sentence

1. Which cells control the opening and closing of stomata?

Ans. Guard cells

2. Name the small lens-shaped pores present on the stems of plants, which serve as site of transpiration.

Ans. Lenticels

3. Which layer on the leaf surface prevents transpiration in desert plants?

Ans. Cuticle layer

4. Why does transpiration occur mainly during the daytime?

Ans. Light helps in opening of the stomata, therefore, transpiration occurs mainly during the daytime.

5. Why do stomata of some desert plants open at night?

Ans. To prevent excess water loss during daytime, stomata of some desert plants open at night.

6. In which season of the year does transpiration in terrestrial plants reaches the peak?

Ans. In dry summer season, transpiration in terrestrial plants reaches the peak.

7. Why are the leaves of many desert plants modified into spines?

Ans. The leaves of many desert plants are modified into spines in order to prevent water loss by transpiration.

8. Why do many desert plants possess dense hairs on the body surface?

Ans. Dense hairs prevent direct air contact on leaf surface and thus, reduce the rate of transpiration. Therefore, many desert plants possess dense hairs on the body surface.

9. Why is the rate transpiration high on the ventral surface of the leaves of dicotyledonous plants?

Ans. Leaves of dicotyledonous plants possess more stomata on the ventral surface. Therefore, the rate of transpiration is higher on that side.

10. Which instrument is used to measure the rate of transpiration?

Ans. Ganong’s potometer

11. Mention the phenomenon through which plants give out excess water in the form of droplets?

Ans. Guttation

12. How is the rate of transpiration affected on a rainy day?

Ans. Since the percentage of water vapour is high in the atmosphere on a rainy day, the rate of transpiration decreases.

13. In which side of an isobilateral leaf, do we find more number of stomata?

Ans. In an isobilateral leaf, stomata are distributed equally on both sides of the leaf.

14. What are the subsidiary cells?

Ans. Plant epidermal cells, surrounding the guard cells, are called subsidiary cells.

15. Give an example of a plant where sunken stomata are present.

Ans. Nerium sp.

16. Who described the mechanism of active K⁺ exchange of opening and closing of stomata?

Ans. Levitt

Fill in the blanks

1. Minimum rate of transpiration occurs through ……….

Ans. Lenticels

2. ………. ions help in the opening of stomata.

Ans. Potassium

3. Xerophytic plants possess ……… stomata.

Ans. Sunken

4. In dorsiventral leaves, maximum number of stomata is seen on the ……… side.

Ans. Ventral

5. ………. is an example of anti-transpirant.

Ans. Abscisic acid

6. In airy environment, rate of transpiration ………..

Ans. Increases

7. A thin and rate. porous cuticle ………. transpiration rate.

Ans. Enhances

8. ………… is a slow and controlled process in plants.

Ans. Transpiration

9. Drooping of plant, due to excess transpiration is called ……….

Ans. Wilting

10. ………. pressure of the guard cell is responsible for the opening of stomata.

Ans. Turgor

State True or False

1. Ganong’s potometer is used to measure the rate of respiration.

Ans. False

2. Plants give out excess water as vapours by a process called evaporation.

Ans. False

3. Transpiration is a physiological process.

Ans. True

4. Maximum rate of transpiration occurs through cuticle.

Ans. False

5. Relative humidity is one of the main controlling factors of evaporation.

Ans. True

SUB-TOPIC – 1.4

MOVEMENT OF WATER, MINERALS, FOOD AND GASES

SUMMARY

Movement of substances like water, gases, minerals, hormones, organic solutes, etc. within the plant body, occur not only from one cell to another or from one tissue to another (short distances) but also from roots to top of plants or from leaves to tip of roots (long distances).
Movement of materials (transport) within plant body, over long distances, through vascular system i.e., xylem and phloem, is called transportation.
Transport of substances over short distance, occurs via the process of diffusion, cytoplasmic streaming and active transport.
Water is absorbed by root hairs and it moves through xylem via two pathways-apoplastic and symplastic pathways.
A hydrostatic pressure, existing in roots pushes the water up through xylem vessels. This pressure is called root pressure.
The excess water absorbed by plant roots is lost in the atmosphere through leaves by the process of transpiration. It helps in ascent of sap. As a result, it also increases the absorption of mineral nutrients from soil.
Transpiration driven ascent of sap through xylem depends on physical forces like cohesion, adhesion and surface tension.
Transpiration creates transpirational pull for absorption and transport of water in plants.
Active and passive transport helps in ion absorption through plant roots. The active uptake of ions requires ATP energy.

Long Answer Type Questions

1. Mention the role of different factors in controlling diffusion.

Ans. Role of different factors in controlling diffusion

Various factors play important role in controlling the rate of diffusion. These are mentioned below.

Temperature: With the increase in temperature of the medium, movement of diffusible molecules increase. Therefore, increase in temperature enhances the rate of diffusion.
Size of diffusible molecules: Larger size of the diffusible molecules restricts their movement. Therefore, larger molecules show slower diffusion rate.
Extent of concentration gradient: Rate of diffusion also depends upon the concentration gradient of molecules of both media. The greater the difference in concentration, the more rapid the diffusion. The closer the distribution of both molecules gets to equilibrium, the slower the rate of diffusion becomes.
Solubility: A molecule with higher rate of solubility, diffuses quickly in a given medium.
Viscosity of the medium: The rate of diffusion is inversely proportional to the viscosity of the medium. That is, if the viscosity of the medium is high, then the rate of diffusion will be lower and vice versa.

2. Mention the salient features of diffusion. Give two examples of diffusion in plants.

Ans. The salient features of diffusion

The salient features of diffusion are as follows-

[1] Diffusible molecules of solid, liquid or gaseous substances can diffuse within either liquid or in gaseous medium. [2] Diffusible molecules move from a region of higher concentration to a region of lower concentration. [3] Diffusion of molecules continues until homogeneity is attained, i.e. the concentration of molecules in both directions becomes same. [4] It is a passive process, i.e. does not require any metabolic energy.

Example of diffusion in plants

Two examples of diffusion in plants are- [1] passive absorption of ions and [2] absorption of O₂ and CO₂ in cells.

3. What is meant by plasmolysis and deplasmolysis? What happens when a living cell is placed in a solution with concentration identical to its protoplasm?

Ans. Plasmolysis

If a cell with intact cell membrane is placed in a hypertonic solution, i.e. a solution with concentration higher than the concentration of the protoplasm of the cell, water from the protoplasm will gradually move out from the cell through its cell membrane by exosmosis. In this case, the protoplasm of the cell will shrink and the cell will appear wrinkled. This phenomenon is called plasmolysis.

Deplasmolysis

If a plasmolysed cell is placed in a hypotonic solution, i.e., a solution with concentration lower than the concentration of the protoplasm of the cell, water from the outer medium will enter into the protoplasm through the cell membrane by endosmosis. In this case, the protoplasm will get more water and the cell will be distended. This phenomenon is called deplasmolysis.

Fate of living cell in isotonic solution

If a living cell is placed in a solution with concentration identical to its protoplasm, i.e., isotonic solution, water from outer medium and from the protoplasm will move through the cell membrane at same rate against each other. Therefore, no change will appear in the cell.

4. Mention the salient features of osmosis. Mention three roles of osmosis in plant body.

Ans. The salient features of osmosis

The salient features of osmosis have been mentioned below. [1] Osmosis occurs only in liquid medium. [2] This process involves the presence of semi-permeable membrane. [3] Solvent molecules move from a region of its higher concentration to a region of lower concentration across the semi-permeable membrane. Movement of solutes does not occur in osmosis. [4] Movement of solvent molecules continues until homogeneity is attained. In osmosis, rate of movement of solvent molecules on either side of the semipermeable membrane becomes the same. [5] It is a passive process, i.e. does not require any metabolic energy.

Role of osmosis in plant body

In plants, osmosis helps in-[1] absorption of water, [2] opening and closing of the stomata and [3] maintaining turgidity of cell.

5. How does ascent of sap occur in a plant?

Ans. Ascent of sap

Transpiration is the process that acts as a driving force for the ascent of sap, from roots to the top of a tree, via xylem vessels. The sequence of events during ascent of sap occurs in the following order-[1] Release of water through stomata by transpiration. [2] Lowering of turgor pressure of leaf cells due to loss of water. [3] Uptake of water by leaf cells from the xylem elements causing a vacuum in the xylem vessels. [4] Generation of a vertically upward suction force on the water column in the xylem vessel, called transpiration pull. [5] Cohesive and adhesive forces of water molecules maintain the uninterrupted water column within the xylem vessels. [6] Roots absorb water and minerals from the soil by imbibition and endosmosis, that moves through the endodermis and increases turgor pressure in the cells surrounding the xylem vessels. [7] The mounting root pressure pushes sap into xylem vessels and starts to drive it against gravity towards the leaves upwards.

6. How is food transported in different parts of the plant body?

Ans. Transportation of food in plant body

Transportation of food in plants occur through sieve tubes of phloem. The cells of sieve tube are arranged one after the other forming a continuous structure. Regarding the mechanism of this process, ‘pressure flow hypothesis’ by Ernst Munch, is the most accepted one. According to this hypothesis, following events occur during food transport in plants.

Transfer of food from mesophyll tissue to sieve tube: In mesophyll tissues, glucose produced by photosynthesis is soon converted into a larger sugar (sucrose). The sucrose solution is then transferred to the sieve tube via bundle sheath cells, phloem parenchyma and companion cells by cell to cell transport.
Creation of pressure within sieve tube: With the entry of sucrose, the cytoplasm of sieve tube becomes denser. As a result, a concentration gradient develops between the sieve tube & neighboring xylem vessels. Due to this, water moves into the sieve tube from xylem vessels by osmosis, thereby, creating additional pressure within the sieve tubes.
Flow of food: This mounting pressure produced within the sieve tube, pushes the food solution to different parts of the plant body. Finally, the sucrose solution enters into the tissue cells from the sieve tube.

7. Write the importance of diffusion and osmosis in living body.

Ans. Importance of diffusion in living body

[1] All physiological processes in living bodies are directly or indirectly dependent on diffusion. [2] Intake of different gases like CO₂, O₂ from atmosphere and movement of gases in inter-cellular spaces take place by this process. [3] Loss of molecules like CO₂, O₂, water vapour, etc., from the plant body during respiration, photosynthesis and transpiration respectively take place by the process of diffusion. [4] Oxygen and carbon dioxide, dissolved in water, are exchanged by diffusion in the lungs of animals.

Importance of osmosis in living body

[1] Plants absorb water by root hairs from the soil by osmosis. [2] Osmosis maintains turgidity in meristematic cells that is required for cell division and growth. [3] Osmosis controls the movement of guard cells and helps in opening and closing of stomata. [4] Osmosis controls entry of water in animal cells and its movement in intercellular space.

Short Answer Type Questions

1. What is meant by transport?

Ans. The process by which food materials, mineral salts, hormones and various gases reach the cells of living organisms and different harmful metabolic waste matters are sent from tissues to respective excretory organs through liquid medium, is called transport.

2. How is facilitated diffusion different from simple diffusion?

Ans. In facilitated diffusion, a carrier molecule or a channel protein in the membrane helps the entry of the diffusible molecules through it, but in simple diffusion, carrier protein is not required.

3. What is meant by passive transport?

Ans. Passive transport is a process by which any molecule or ion of a substance passes through cell membrane along concentration gradient without consuming any metabolic energy. Example· Diffusion and osmosis.

4. What is meant by active transport?

Ans. Active transport is a process in which any molecule or ion, with the help of some metabolic energy, pass through a cell membrane by the help of carrier protein, against concentration gradient. Example-Intake of glucose molecules by a cell.

5. What is diffusion?

Ans. The physical process by which molecules or ions of any substance, move from a region of higher concentration to a region of lower concentration, with the help of their own kinetic energy, is called diffusion. Example-Aroma of incense stick spreads to all corners of the room by diffusion.

6. What is meant by osmosis?

Ans. If two solutions of different concentration, prepared from the same liquid solvent, are separated by a semi-permeable membrane, the solvent molecules move from the region of higher solvent concentration towards the region of lower solvent concentration, until equilibrium is attained. This physical phenomenon is known as osmosis. Example-Raisins swell in water due to osmosis.

7. What is meant by facilitated diffusion?

Ans. Facilitated diffusion is a type of diffusion, where diffusible molecules pass through a cell membrane with the help of some channel proteins present in it. In this process, no metabolic energy is needed.

8. What is meant by root pressure? Mention the importance of root pressure.

Ans. Root pressure: The cumulative turgor pressure created in the cells, surrounding the xylem vessels of the root, due to absorption of sap is known as root pressure.

Importance: Root pressure pushes the sap into the xylem vessels through their thick cell wall and drives the sap upward.

9. What is cohesive force? What is meant by adhesive force.

Ans. Cohesive force: The force of attraction between two particles or molecules of a same substance, is called cohesion force. Inside the xylem vessels, water droplets remain attached to each other by cohesive force.

Adhesive force: The force of attraction between the particles of different substances, is called the adhesive force. The water droplets remain attached to the wall of xylem vessel by adhesive force.

10. What is transpiration pull?

Ans. In xylem vessels, uninterrupted water column is formed by cohesive-adhesive force. These columns extend from the roots to the stomata of the leaves. During transpiration, when a molecule of water leaves the stomatal opening, it applies an upward pulling force on the receding water column, which is known as transpiration pull.

11. What is meant by ascent of sap?

Ans. The transport of water and minerals, known as sap, from root to the leaves through xylem vessels against the force of gravity, is known as the ascent of sap.

12. The fragrance of a perfume, sprayed at one corner of a room, can be felt in the entire room after some time. Which phenomenon is responsible for this?

Ans. The fragrance of a perfume, sprayed at one corner of a room, can be felt in the entire room after some time due to a phenomenon called diffusion.

13. Name the forces which control the ascent of sap in plants.

Ans. The forces which control the ascent of sap in plants are [1] root pressure, [2] transpiration pull, [3] adhesive force and [4] cohesive force.

14. Give two examples of liquid-liquid diffusion.

Ans. Two examples of liquid-liquid diffusion are[1] Diffusion between water and ink and [2] Diffusion between water and sugar syrup.

15. Give two examples of liquid-solid diffusion.

Ans. Two examples of liquid-solid diffusion are[1] Diffusion between water and sugar crystal and [2] Diffusion between water and copper sulphate (CuSO₄) crystals.

16. Give two examples of solid-gas diffusion.

Ans. Two examples of solid-gas diffusion are[1] Diffusion between asafoetida and air and [2] Diffusion between camphor and air.

17. What is absorption in plants?

Ans. The physical process by which water and mineral salts enter the plant body through root hair by the process of endosmosis, is called absorption.

18. Why the water potential of any solution is always negative?

Ans. The water potential of pure water is zero. Thus, solute mixed any solution always has negative water potential.

Very Short Answer Type Questions

Multiple Choice Questions & Answers [MCQ]

1. Rate of diffusion increases with the-

A. Increase in temperature of the medium

B. Increase in viscosity of the medium

C. Decrease in relative difference in concentration of two media

D. All of these

Ans. A

2. Which type of transport never needs any carrier?

A. Simple diffusion

B. Osmosis

C. Both A and B

D. Ion absorption

Ans. C

3. In diffusion of molecules, the main driving force is the

A. Electrical gradient

B. Concentration gradient

C. Both A and B

D. None of these

Ans. C

3. O₂ is absorbed in the living cells by-

A. Diffusion

B. Osmosis

C. Active absorption

D. None of these.

Ans. A

5. The main cause of diffusion pressure is-

A. Size of diffusible molecules

B. Velocity of the diffusible molecules

C. Weight of the diffusible molecules

D. Viscosity of the medium

Ans. B

6. The phloem element which helps in the transport of food material, is

A. Sieve tube

B. Companion cells

C. Both A and B

D. None of these

Ans. C

7. Increase in size of diffusible molecules results into-

A. Slower rate of diffusion

B. Faster rate of diffusion

C. No change in diffusion rate

D. Stoppage of diffusion

Ans. A

8. Increase in viscosity of medium-

A. Has no role in diffusion

B. Has negative role in diffusion rate

C. Has positive role in diffusion rate

D. Stops diffusion completely

Ans. B

9. If a living cell is placed in a hypertonic solution, the protoplasm-

A. Shrinks

B. Swells

C. Remains as it is

D. Gets dissolved in the solution

Ans. A

10. In active transport, sodium and potassium ions-

A. Jointly enter into a cell through cell membrane

B. Move against each other through cell membrane

C. Never enter in a cell through cell membrane

D. Sodium ion enters but potassium ion does not enter in a cell

Ans. B

Answer in a single word or sentence

1. By which process water molecules enter through the cell membrane of root hair cells?

Ans. Endosmosis

2. How do cells of aquatic plants absorb dissolved CO₂ from water?

Ans. By diffusion

3. How is facilitated diffusion different from active transport?

Ans. In active transport, chemical energy is needed in the form of ATP but facilitated diffusion does not need energy.

4. In which type of active transport, two different diffusible molecules or ions move against each other at the same time?

Ans. Antiport

5. In which type of active transport, a single type of ion or molecule moves through the cell membrane?

Ans. Uniport

6. In which type of active transport, two different ions or molecules move together in the same direction through a cell membrane?

Ans. Symport

7. Name two biomolecules, which pass through the cell membrane by active transport.

Ans. Glucose and amino acids

8. Mention two matters, which are taken into a cell by passive transport.

Ans. Oxygen and water

9. Diffusion pressure deficit increases in leaves during daytime due to which phenomenon?

Ans. Transpiration

10. How does sap pass through the cells of cortex of root?

Ans. By cell to cell osmosis

11. Which pressure is created within the xylem vessels by the inflow of sap from the root?

Ans. Root pressure

12. Which force pulls the sap up from roots to the leaves of tall plants?

Ans. Transpiration pull

13. How much pulling force may transpiration pull create in a xylem vessel?

Ans. About 20 atmospheric pressure

14. How does the size of diffusible molecules affect the rate of diffusion?

Ans. Larger size of diffusible molecules reduces the rate of diffusion and vice versa.

15. How does the density of diffusible molecules affect the rate of diffusion?

Ans. Higher density of diffusible molecules increases the rate of diffusion.

16. Due to which pressure young meristematic cells grow in size?

Ans. Turgor pressure

17. Name the scientist who proposed the ‘Root Pressure Theory’.

Ans. British scientist Stephen Hales

18. Who proposed the ‘Transpiration pull and Cohesion Tension Theory’ to explain the ascent of sap?

Ans. Scientists Dixon and Joly

19. Give an example of an impermeable membrane.

Ans. Plastic sheet

20. Give an example of a permeable membrane.

Ans. Cell wall

21. By which type of active transport, two different diffusible molecules are carried by a single carrier protein?

Ans. Coupled transport

Fill in the blanks

1. …………. does not need any metabolic energy for transportation.

Ans. Water

2. In osmosis, the molecules of ………… move from a region of low concentration to a region of high concentration.

Ans. Solvent

3. Diffusion occurs due to difference in ………. of the two media.

Ans. Density

4. The physiological process for which a semipermeable membrane is required, is called ………

Ans. Osmosis

5. The process which helps herbs to stand erect on the ground, is ………..

Ans. Osmosis

6. The pressure flow hypothesis was given by scientist …………

Ans. Munch

7. The cell membrane of a living cell is usually a kind ……… of permeable membrane.

Ans. Selectively

8. The passage of water from one cell to the next is called ………. osmosis.

Ans. Intercellular

9. When a cell is placed in a hypotonic solution, water moves into the cell, this flow is called ……….

Ans. Endosmosis

10. The most acceptable theory of ascent of sap is ………..

Ans. Cohesion-tension theory

State True or False

1. ‘Root Pressure Theory’ was proposed by Curtis.

Ans. False

2. Transpiration pull helps in the ascent of sap.

Ans. True

3. Acell shrinks when placed in hypotonic solution.

Ans. False

4. Air bladder of fish is an example of a semipermeable membrane.

Ans. True

5. Symport and antiport are types of coupled transport.

Ans. True

6. Only downward transport of food materials takes place in phloem.

Ans. False

TOPIC – 2

RESPIRATION

SUB-TOPIC – 2.1

ORGAN-LEVEL RESPIRATION

SUMMARY

The process by which foodstuffs are oxidised in cells to release their energy for utilisation in the body is known as respiration. In respiration O₂ is used up and CO₂ is released. Respiratory organs are semipermeable, most well-developed gas exchange surface and also presence of profuse network of blood vessels. The chief respiratory sites of plants are stomata, lenticels, pneumathodes and pneumatophores. The different respiratory organs of different animals are seen like body surface, trachea, gill, lungs, etc. Accessory respiratory organ of Koi (Anabas), Magur (Clarias), Singhi (Heteropneustes) are also used where oxygen supply is scanty, so respiration occurs by gills.
In case of human being respiration is associated with lungs, trachea, bronchi, bronchioles, diaphragm and respiratory muscles.

Long Answer Type Questions

1. What is inhalation and exhalation? Briefly describe the salient features of the respiratory organs of animals.

Ans. Inhalation

The mechanical process, by which organisms take in air from the environment, is called inhalation.

Exhalation

The mechanical process, by which living organisms give out carbon dioxide-rich air from their respiratory organs, into the environment, is called exhalation.

Salient features of the respiratory organs of animals

Moistness: Moist cell membrane of unicellular organisms and moist skin of earthworms, leeches, frogs and toads acts as respiratory organ. Atmospheric oxygen enter into the blood vessels through these moist skin, by diffusion.
Surface area: A respiratory organ should have a large surface area because surface area improves its efficiency by transporting or exchanging enough oxygen. The thin and numerous lamellae of gills and densely packed alveoli of lungs make these two organs best suited for aquatic and aerial respiration respectively.
Vascularity: A respiratory organ should be well vascularised. This helps in better exchange of the respiratory gases. Rich distribution of blood capillaries in gills and lungs make these respiratory organs highly efficient for gaseous exchange.

2. Explain the role of different parts of plant body in gaseous exchange.

Ans. Role of different parts of plant body in gaseous exchange

Plants do not have typical respiratory organs like animals. Few sites on a plant body help in exchange of O₂ and CO₂. These are stomata, lenticels, pneumatophores etc.

Stomata: Stomata are the tiny pores, present on the surface of leaves, tender stems and other parts of the plant body that help in the exchange of gases. These are the special intracellular spaces bordered by two specialised bean-shaped parenchyma cells, called guard cells, which open and close. Thus, allowing exchange of gases.
Lenticels: Lenticels are lens-shaped spaces, formed in the cracks on the bark of trees. These function as pores, providing the pathway for direct exchange of gases between the internal tissues and atmosphere through the bark, which is otherwise impermeable to gases.
Pneumatophores: Halophytes (mainly mangrove trees) grow on saline muddy soil in the delta region of rivers. This soil has poor oxygen content. To counter it, some roots of these plants grow vertically upward against gravity and come above the soil. These roots are highly porous. These are called pneumatophores or breathing roots, which help in the exchange of gases directly from the air.

3. How do insects perform organ-level respiration with the help of trachea?

Ans. Tracheal respiration in insects

In insects (such as cockroach), a network of a very thinwalled tubes are spread in the body. These tubes are known as trachea. Air enters into the tracheal system through tiny paired pores present on pleurites along the two sides of the body. These pores are called spiracles. Trachea ramifies or form branches inside the body cavity, longitudinally and transversely to form a tracheal network. The finest ends of tracheal branches are called tracheoles. Each tracheole ends in a large tracheal end cell, which gives off some fine cytoplasmic processes. These processes enter into intercellular tissue fluid. Gaseous exchange occurs between the tracheal end cells and tissue fluid and finally from tissue fluid to the cells by the process of diffusion.

4. Briefly describe the main respiratory organ of fishes. How do fishes perform aquatic respiration?

Ans. Structure of respiratory organ of fishes

Gills perform the respiratory function in fishes. In case of cartilaginous fishes, these are present in gill clefts and in bony fishes, these are held in gill chambers at two sides of the head, covered with a bony plate, called the operculum. A gill has a curved bony skeletal structure, called gill arch. Two rows of thin and flat gill filaments are densely arranged in a parallel manner along the gill arch like teeth of a comb. Numerous, very thin membranous folds emerge from either side of a gill filament, called gill lamellae. Gill filaments and lamellae are supplied with dense network of blood capillaries.

Mechanism of aquatic respiration in fishes

Fishes continuously open and close their mouth. When they open their mouth, fresh water flows into the buccal cavity. They open the opercula to allow water to pass through gills to flood the gill filaments before leaving the two gill chambers. As the water passes through the gills, O₂ diffuses into the blood capillaries and CO₂ diffuses out in the water. This is how, fishes perform aquatic respiration.

5. Describe the structure of human lung. Mention its function.

Ans. Structure of human lung

Lungs are paired, sac-like structure located in the thoracic cavity of human body, well protected by the rib cage. Lungs remain separated from the abdominal cavity by a muscular sheet or membrane, called the diaphragm. Each lung is covered with a double layered covering called pleura. The outer layer is called parietal and the inner one is called visceral pleura. A fluid-filled space is present in between these two layers. The left lung is slightly smaller with two lobes to accommodate the heart and the right one is larger with three lobes. A long, thin walled, tubular wind-pipe or trachea goes down vertically along the medial chest line and divides into two bronchi (singular-bronchus) before entering the lungs. Each bronchus then ramifies several times, from finer to finest air tubules, called bronchioles. Finally, each of the bronchioles ends into a tiny balloon shaped alveolus (plural – alveoli). Thus, countless alveoli form a lung. Two human lungs are composed of 30 to 50 crore of alveoli. Wall of each alveolus is rich in blood capillaries. That is why healthy lungs appear reddish pink.

Function

[1] Lungs are the chief respiratory organs in man. It helps in respiration. [2] In the lungs O₂ enters from the alveolar air into the blood capillaries and CO₂ comes out from the blood capillaries into the alveolar air.

6. Write about the accessory respiratory organs with examples. Mention its necessity in animals.

Ans. Accessory respiratory organs

In some bony fishes, living in muddy water where oxygen supply is scanty, respiration by gills is supplimented by a special organ called accessory breathing organs. e.g. Koi (Anabas), Magur (Clarias), Singhi (Heteropneustes).

The name of accessory respiratory organ of Magur is called arborescent organ; for Singhi it’s tubular airsac and for Koi it’s labyrinthine organ.

Necessity in animals

[1] These fishes are unable to live submerged in water and allowed to grasp air through mouth by lifting his head above water when oxygen concentration is very low in water. Absorption of oxygen appears to be primary function of the accessory respiratory organ. [2] Some fishes have the natural instinct to make short excursion to the land from the primal aquatic homes.

9. What is meant by active and passive smoking? Write the poisonous effect of smoking.

Ans. Active smoking

Active smoking is the intentional inhalation of tobacco smoke by a smoker. Smokers puff directly from the cigarettes.

Passive smoking

Passive smoking is the involuntary inhalation of smoke from tobacco products. Such smoke is called Secondhand Smoke (SHS) or Environmental Tobacco Smoke (ETS).

The poisonous effect of smoking

[1] Emphysema means excess air in the lungs, caused by many years of smoking, resulting chronic infection, obstruction of airways makes expiration difficult, bronchiolar obstruction increases etc., [2] Lung cancer or carcinoma occurs due to many carcinogenic agents present in tobacco smoke, [3] Chronic obstructive pulmonary disease (COPD), [4] Heart disease, stroke, [5] Eye diseases, [6] Increases risk of tuberculosis, [7] Problems of the immune system including rheumatoid arthritis.

Short Answer Type Questions

1. What is meant by organ-level respiration?

Ans. The physical process involving the intake of oxygen in the body and release of carbon dioxide from the body, with the help of typical respiratory organs, is known as organ-level respiration.

2. How do unicellular organisms perform organlevel respiration?

Ans. Unicellular organisms do not possess organs, therefore they do not perform organ-level respiration, but perform gaseous exchange of O₂ and CO₂ by diffusion through cell membrane.

3. How do sponges and jellyfishes perform organ-level respiration without respiratory organ?

Ans. Sponges and jellyfishes do not have any respiratory organ. Their body cells perform gaseous exchange by diffusion through respective cell membranes. This is how they perform organlevel respiration.

4. How does the skin of earthworm act as a respiratory organ?

Ans. The skin of earthworm always remain moist. Atmospheric oxygen is dissolved in the film of fluid over the skin surface. By diffusion, this gas gets mixed in the blood of the capillaries below the skin. Blood plasma of earthworm contains haemoglobin, which receives oxygen and carries it to different parts of the body. This is how the skin of earthworm acts as a respiratory organ.

5. Mention the role of spiracles and trachea in the respiration of cockroaches.

Ans. In cockroaches, 10 pairs of spiracles are present at the two lateral sides of the body. Through these pores air enters into the trachea. Trachea forms an intricate network inside the body of cockroach, which ramifies into several branches that help in gaseous exchange.

6. When and how toads and frogs perform organlevel respiration by skin?

Ans. Frogs and toads perform organ-level respiration by skin during hibernation. They have moist, naked glandular skin. This is well permeable to gases. The cutaneous capillaries below the skin can absorb Toad oxygen from atmosphere by diffusion, which may fulfill their need of oxygen during hibernation.

7. How does smoking affect lungs?

Ans. Smoke of cigarettes and bidis contains different harmful compounds. This smoke enters the human lungs and forms a sticky tar which accumulates in the walls of the alveoli. Due to continuous smoking gradually the lungs lose the ability of gaseous exchange. The harmful compounds cause several diseases like emphysema, COPD and even lung cancer.

8. How many types intercostal muscles are there? Name them.

Ans. There are two types of intercostal muscles-external intercostal muscles and internal intercostal muscles. These muscles are present in between 12 pairs of rib bones.

9. How do plants respire?

Ans. Plants respire with the help of openings or tiny holes called stomata that present on the underside of leaves. Stomata are able to trap air containing oxygen and carbon dioxide and exchange of gases occurs within the plant cells. Other respiration site of plants are lenticels and cuticle.

10. How does the diaphragm help in breathing?

Ans. The diaphragm is a dome-shaped muscle underneath the lungs. When it contracts, oxygen rich air is pulled inside the lungs and when it relaxes, CO₂ is pumped out from the lungs.

Very Short Answer Type Questions

Multiple Choice Questions & Answers [MCQ]

1. Which feature is essential for a respiratory organ?

A. It must have wide surface area

B. It must be wet

C. It must be well vascularised

D. All of these

Ans. D

2. The respiratory organ of herbs are-

A. Stomata

B. Stomata and lenticels

C. Stomata and cuticle

D. Cuticle

Ans. C

3. Halophytes respire with-

A. Stomata

B. Stomata and cuticle

C. Stomata and pneumatophores

D. Pneumatophores and cuticle

Ans. C

4. Pneumatophores collect air from the-

A. Atmosphere

B. Mud

C. Saline water

D. Moist soil

Ans. A

5. The most efficient organs for respiration in plants are-

A. Stomata

B. Lenticels

C. Pneumatophores

D. Cuticular pores

Ans. A

6. Respiratory organ of starfish is ……….

A. Tube feet

B. Lungs

C. Book lung

D. Gills

Ans. A

7. The most efficient organ for aerial respiration in animals is

A. Skin

B. Lungs

C. Book lungs

D. Trachea

Ans. B

8. Trachea of insects supply oxygen to-

A. Haemolymph

B. Body fluid

C. Intercellular fluid

D. Cells

Ans. C

9. Spiracles of cockroach are present on-

A. Tergite

B. Sternite

C. Pleurite

D. Pronotum

Ans. C

10. Air enters in the tracheal network of insects by-

A. Stomata

B. Tracheoles

C. Pleurites

D. Spiracles

Ans. D

Answer in a single word or sentence

1. Which physiological process provides energy to perform life activities?

Ans. Respiration

2. Name two organisms, which exchange respiratory gases through body surface.

Ans. Amoeba and Hydra

3. Which typical respiratory organ is seen in halophytic plants?

Ans. Pneumatophore or breathing root is the typical respiratory organ of the halophytic plants.

4. Name two invertebrates, which perform organlevel respiration by skin.

Ans. Earthworms and leeches

5. Name two invertebrates, which perform organlevel respiration by gills.

Ans. Crabs and prawns

6. Name a vertebrate, which is capable of performing organ-level respiration by skin.

Ans. Frogs are capable of performing organ-level respiration through skin.

7. Which parts of gills act as the site of gaseous exchange?

Ans. Gill lamellae

8. Which part of lungs act as the site of gaseous exchange?

Ans. Alveoli of lungs act as the site of gaseous exchange.

9. Mention a common feature of gill lamellae and alveoli of lungs.

Ans. Both gill lamellae and alveoli of lungs are well vascularised.

10. Name two parts of the human respiratory system, which do not take part in gaseous exchange?

Ans. Trachea and bronchioles

11. Name the opening through which, air enters into the trachea from pharynx.

Ans. Glottis

12. Where is larynx located?

Ans. Larynx is located at the upper end of the trachea.

13. Where is bronchus located?

Ans. Bronchus is located at the lower end of the trachea.

14. Which bony structure holds the gill lamellae in fishes?

Ans. In fishes, the gill lamellae are held by bony gill arch.

15. Which bony plate covers the gill chamber of bony fishes?

Ans. Operculum

16. Which fine tubular structures supply air directly to the cells in the body of insects?

Ans. Tracheoles supply air directly to the cells in the body of insects.

17. How much air does a healthy adult human inhale or exhale during normal breathing?

Ans. A healthy adult human inhales or exhales 500 ml of air during normal breathing.

18. What is the maximum volume of air, which a healthy adult human can hold in the lungs?

Ans. A healthy adult human can hold a maximum of 4500-5000 ml of air in the lungs.

19. Name the flattened sheet of respiratory muscle, which separates the thoracic cavity from the abdominal cavity.

Ans. The flattened sheet of respiratory muscle which separates the thoracic cavity from abdominal cavity, is called diaphragm.

20. How can a person increase the vital capacity of the lungs?

Ans. A person can increase the vital capacity of the lungs by performing breathing exercises or ‘pranayam’.

Fill in the blanks

1. Respiration is a/an ……….. process.

Ans. Anabolic

2. Limulus respire through ………

Ans. Bookgills

3. The respiratory organ of cockroach is ……….

Ans. Trachea

4. Spiders respire through ……….

Ans. Booklung

5. Todpoles breath through external ……….

Ans. Gills

6. During hibernation, animals respire through ……….

Ans. Skin

7. Accessory respiratory organ found in ……….

Ans. Somebony fishes

8. Whales respire through ……….

Ans. Lungs

9. In blood, oxygen is transported as ……….

Ans. Oxyhaemoglobin

10. ………. is the cartilaginous covering present at the entrance of the larynx.

Ans. Epiglottis

State True or False

1. A typical respiratory organ should not be moist.

Ans. False

2. Pneumatophores are called ‘breathing roots, which grow against gravity.

Ans. True

3. Frogs show cutaneous respiration.

Ans. True

4. Gills are covered with bony plates, called cranium.

Ans. False

5. Each bronchus of lung ramifies reveral times, from finer to finest air tubules, called bronchioles.

Ans. True

6. Breathing involves two phases-inspiration and expiration.

Ans. True

7. During expiration diaphragm expands.

Ans. True

8. Smokers develop a chronic lung disease, called emphysema.

Ans. True

9. During inspiration, intercostal muscles relax to push the ribs downwards.

Ans. False

10. Tuberculosis is caused by Mycobacterium tuberculosis.

Ans. True

SUB-TOPIC – 2.2

CELLULAR LEVEL RESPIRATION

SUMMARY

All living organisms require a continuous supply of energy for carrying out various life processes.
The biochemical process which involves degradation of food in stepwise oxidation with the release of energy inside the living cells is called respiration.
Cellular respiration is an enzyme regulated biological oxidation of organic substances inside the living cells that releases energy.
Steps of cellular respiration are glycolysis, krebs cycle and terminal respiration or electron transport system (ETS).
Cellular respiration are of three types-[1] Aerobic respiration [2] Anaerobic respiration [3] Fermentation.
Fermentation occure in absence of oxygen and release small amount of energy. Mainly two types of fermentation are there, lactic acid fermentation and alcoholic fermentation. Alcoholic fermentation is a process in which yeast convert sugar into alcohol, whereas lactic acid fermentation only occure in animal cell.

Long Answer Type Questions

1. Briefly describe the process of glycolysis with the help of a schematic diagram.

Ans. Glycolysis

Glycolysis is the primary step of cellular respiration occurring in cytoplasm of all living cells. By this process, glucose is enzymatically broken into two pyruvic acids (3C) through a straight chain reaction path. Each step requires a specific enzyme which acts as biocatalyst. – In this metabolic process, glucose is converted into glucose 6-phosphate and then to fructose 1, 6bisphosphate. In this phase, two ATP molecules are consumed. In the next step, this fructose 1, 6bisphosphate is broken into two 3C compoundsglyceraldehyde 3-phosphate and dihydroxyacetone phosphate. Enzymatically, this dihydroxyacetone phosphate is transformed into glyceraldehyde 3phosphate. At this phase, two molecules of glyceraldehyde 3-phosphate transforms into 2- phosphoenol puruvate via 3 phosphoglycerate and 2 phosphoaglycerate by stepwise manner and finally 2-phosphoenol pyruvate transformed into 2 molecules of pyruvic acid. By glycolytic breakdown of one molecule of glucose, four ATP molecules are produced and two are consumed, therefore, two ATP molecules are net gained. In this reaction, two molecules of NADH+H⁺ are also produced.

2. Name the enzyme present in the oxysomes of mitochondria. How does terminal respiration occur in a cell of any aerobic organism?

Ans. Enzyme in oxysome

ATP synthetase enzyme is present in the oxysomes of mitochondria.

Terminal respiration

Terminal respiration is the final phase of aerobic reaction, which involves the production of ATP and H₂O. This is the energy generating, i.e., ATP producing final phase of cellular respiration. NADH+H⁺ and FADH₂, (reduced hydrogen carriers) which are produced during glycolysis, decarboxylation of pyruvic acid & Krebs cycle, are oxidised in this reaction path. At first, hydrogen atoms are released from NADH+H⁺ and FADH₂. Then each hydrogen atom releases one electron, which is then transported by iron containing electron carriers cytochrome. This process generates huye chemical energy, which finally produces energy-rich ATP molecules. So, this reaction pathway is also known as electron transport system or ETS. The hydrogen atoms, released from NADH+H⁺ and FADH₂ finally react with O₂ present in the atmosphere to produce H₂O.

3. Briefly describe the reaction process of Krebs cycle with the help of schematic diagram.

Ans. Krebs cycle

Krebs cycle is the second major phase of aerobic respiration. This reaction occurs in the mitochondria in a cyclic reaction path, where a 6 carbon substrate, citric acid is converted step-by-step into 5C and 4C substrates. The substrate of Krebs cycle is acetyl Co-A, which is produced from pyruvic acid, the end product of glycolysis. In Krebs cycle, acetyl Co-A and oxaloacetic acid combine to form citric acid. This is the initial product of this cycle.

In this process CO₂, is released in steps. The other products are NADH+H⁺, FADH₂ and GTP. This GTP is transformed into ATP directly. The other two products NADH+H⁺ and FADH₂ are oxidised by dissociation of hydrogen through electron transport system.

4. Mention the significance of respiration.

Ans. Significance of respiration

Conversion of energy and ATP production: The potential energy stored in food, is converted into kinetic energy by respiration. This energy is dissipated as heat and some portion of it is stored in ATP within the cells, as chemical energy for future use.
Maintenance of O₂-CO₂ balance: During respiration, atmospheric oxygen is consumed and carbon dioxide is released. Whereas, photosynthesis does the opposite. Thus, photosynthesis and respiration jointly maintain the balance of oxygen and carbon dioxide in the environment.
Economic importance: Fermentation of flour (starch) by yeast makes cakes and breads puffy. Ethyl alcohol is a fermentation product, which has great economic importance for medicinal purpose and to prepare alcoholic beverages. Cheese, butter, curds are prepared by fermentation of milk. Some vitamins like vitamin B₁, vitamin B₁₂, vitamin C, etc. are also produced in the body by bacterial fermentation.
Excretion: Various excretory products like ammonia, ketone body, alcohol, water vapour, volatile fatty acids, etc., are given out of the body through respiration.
Maintenance of Acid-Base balance: Since CO₂ is liberated during respiration, it helps to maintain acid-base balance in the body.
Regulation of temperature: When animals exhale, certain amount of heat is liberated from their bodies, thus regulating the temperature of the body.
Light generation: Certain deep-sea animals, like Ctenophorans and insects, like fireflies can generate light. This phenomenon is called bioluminescence. This light is generated from the chemical energy, gained by respiration.
Electrical power generation: Some fishes like Torpedo and electric eel can generate huge electrical power within their electric organs to kill preys. Respiration produces this power from chemical energy.

Short Answer Type Questions

1. What is respiration?

Ans.Respiration is a catabolic process, which involves the intake of oxygen within cells and liberation of kinetic energy by oxidation of food or respiratory substrates, for performing different life activities.

2. What is meant by cellular respiration?

Ans.The bio-chemical process by which food or respiratory substrates are oxidised within the cells to liberate kinetic energy in the form of ATP, is known as cellular respiration.

3. What is meant by aerobic respiration?

Ans.Aerobic respiration is a type of cellular respiration, where respiratory substrate is oxidised completely in the presence of free oxygen to discharge carbon dioxide and water as by-products and to liberate the total energy from the substrate.

4. Write down the chemical equation of aerobic respiration.

Ans.The chemical equation of aerobic respiration is mentioned below.

5. What is meant by fermentation?

Ans.Fermentation is a typical anaerobic, enzymedependent process of incomplete oxidation of sugar, which producès different organic compounds (ethyl alcohol, lactic acid, butyric acid etc.) with partial liberation of energy from the respiratory substrate.

6. What is meant by alcoholic fermentation?

Ans.Alcoholic fermentation is a special type of fermentation, where yeast (Saccharomyces) ferments sugar (glucose, fructose, sucrose etc.) solutions to produce ethyl alcohol with the help of a typical enzyme, zymase. In this process, CO₂ and a little energy are also released.

7. What is meant by lactic acid fermentation?

Ans.The fermentation process, where certain bacteria (Lactobacillus) ferment milk-sugar (lactose), to produce lactic acid in absence of O_2, liberating a little amount of energy (36 kcal), called lactic acid fermentation.

8. What is glycolysis?

Ans.Glycolysis is an oxygen-independent reaction, where glucose, within the cytoplasm of living cells, is broken into pyruvic acid molecules through a series of enzyme-mediated reactions and in this process produce NADH+H⁺, H₂O and ATP as by-products.

9. Why is glycolysis called EMP path?

Ans.Scientists Embden, Meyerhof and Parnas discovered the reaction pathway of glycolysis. Therefore, after the first letter of the names of these three scientists, glycolysis is known as EMP path.

10. Why is Krebs cycle known as TCA cycle and citric acid cycle?

Ans.Citric acid is produced in the first step of Krebs cycle, therefore it is called Citric acid cycle. Citric acid contains three carboxylic groups, therefore, this cycle is also known as tricarboxylic acid cycle or TCA cycle.

11. What is meant by terminal respiration?

Ans.Terminal respiration is the last step of aerobic respiration, where NADH+H⁺ and FADH₂, produced in glycolysis and Krebs cycle, are oxidised by electron carriers, situated in the inner membrane of mitochondria, and hydrogen is oxidised by the atmospheric oxygen to form water and produce ATP.

12. Mention the four phases involved in aerobic respiration.

Ans.The four phases involved in aerobic respiration are [1] glycolysis, [2] oxidation of pyruvate, [3] krebs cycle and [4] terminal respiration.

13. What is ATP synthases?

Ans.ATP synthase is a enzyme, present on the inner membrane of mitochondria and helps in the synthesis of ATP.

14. Why respiration is called catabolic metabolism?

Ans.During respiration, organic substance present in a cell is oxidised to form energy, carbon dioxide and water, as a result the dry weight of an organism is reduced, therefore respiration is called catabolic metabolism.

15. What is muscle fatigue?

Ans.The process by which lactic acid is accumulated in muscles due to excessive contraction for which muscles lose its ability to contract. This phenomenon is called muscle fatigue.

16. What is combusion?

Ans.Combusion is a Physicochemical process in which oxidation of organic or inorganic substances takes place in presence of free oxygen with the release of large amount of heat, light and carbon dioxide. This process is not controlled by protoplasm and enzymes.

17. What is RQ?

Ans.The ratio of volume of CO₂ given out during respiration with the volume of O₂ taken in during respiration is called RQ (Respiratory quotient).

18. What is surfectant?

Ans.Surfectant is a chemical substance present within the lung-alveoli which helps to maintain reduced alveolar surface tension when thoracic cavity enlarges during inspiratory phase and prevent the collapsing of alveoli during expiration.

Very Short Answer Type Questions

Multiple Choice Questions & Answers [MCQ]

1. An example of anaerobic fungus, is—

A. Chlorella

B. Yeast

C. Agaricus

D. None of these

Ans. B

2. Which phase of respiration directly involves atmospheric O₂?

A. Glycolysis

B. Krebs cycle

C. Terminal respiration

D. Krebs cycle and terminal respiration

Ans. C

3. Which of the following is involved in anaerobic respiration?

A. HNO₃

B. N₂O

C. NH₃

D. NO₃

Ans. D

4. One molecule of glucose breaks into …….. molecules of pyruvic acid in glycolysis.

A. 1

B. 2

C. 3

D. More than 3

Ans. B

5. Production of CO₂ occurs during-

A. Glycolysis and Krebs cycle

B. Terminal respiration

C. Krebs cycle

D. All of these

Ans. C

6. In anaerobic respiration, the terminal respiration path is ……….

A. Present

B. Absent

C. Long

D. Short

Ans. B

7. EMP pathway is biochemically known as-

A. Glycolysis

B. Krebs cycle

C. Terminal respiration

D. Electromotive pressure

Ans. A

8. The other name of terminal respiration is-

A. EMP pathway

B. ETS

C. TCA cycle

D. ATP

Ans. B

Answer in a single word or sentence

1. Which type of respiratory process generates energy inside the living cell?

Ans. Internal or cellular respiration

2. What is meant by respiratory substrate?

Ans. The compounds, which are oxidised during cellular respiration to release energy, are known as respiratory substrates.

3. In which form does respiratory substrate liberate energy during cellular respiration?

Ans. During cellular respiration, energy is liberated from respiratory substrate in the form of ATP.

4. Where do reactions of glycolysis take place during cellular respiration?

Ans. In the cytoplasm

5. What is meant by glycolysis?

Ans. The breakdown of glucose by enzymes, releasing energy and pyruvic acid, is called glycolysis.

6. How many pyruvic acid molecules are formed at the end of glycolysis?

Ans. Two molecules of pyruvic acid are formed …..

7. Where do the reactions of Krebs cycle take place?

Ans. In mitochondria

8. Mention the by-products of Krebs cycle.

Ans. CO₂, reduced NAD and FAD (i.e. NADH+H⁺ and FADH₂ respectively).

9. Which reactions of respiration occur in the inner membrane of mitochondria?

Ans. Electron transport system or terminal respiration occur in the inner membrane of mitochondria.

10. In which phase of aerobic respiration is ATP produced?

Ans. ATP is produced by ETS (electron transport system) of aerobic respiration.

11. Mention two organic end-products of anaerobic respiration.

Ans. Lactic acid and ethyl alcohol

12. Name a type of animal tissue, where anaerobic respiration takes place.

Ans. Voluntary muscles of animals

13. Which organic compound is formed in muscle cells due to anaerobic respiration?

Ans. Lactic acid is formed in muscle cells due to anaerobic respiration.

14. Which organic compound is produced in plant cells due to anaerobic respiration?

Ans. Ethyl alcohol

15. Which organic compound is produced by fermentation of milk?

Ans. Lactic acid

16. Which organic compound is produced by fermentation of glucose or sucrose in oxygen free condition?

Ans. Ethyl alcohol is produced by fermentation of glucose or sucrose in oxygen free condition.

17. Name an enzyme present in yeast, which helps in alcoholic fermentation of sugar solution.

Ans. Enzyme zymase is present in yeast, which helps in alcoholic fermentation of sugar solution.

18. Which enzyme, present in Lactobacillus, helps in fermentation of milk-sugar?

Ans. Lactate dehydrogenase is the enzyme, present in Lactobacillus, which helps in fermentation of milk-sugar.

19. Where does aerobic respiration take place?

Ans. Aerobic respiration takes place in all organisms living in air, water and soil in contact with free molecular oxygen.

20. How many high energy bonds are present in ATP?

Ans. Two high energy bonds are present in ATP.

21. How much energy is released during hydrolysis of 1 molecule of ATP?

Ans. 7.3 kcal energy

22. Which cell organelles are called ‘energy transducers’?

Ans. Those cell organelles which convert one form of energy into another, are called ‘energy transducers’.

Fill in the blanks

1. In respiration, about ………. of the free energy is entrapped in ATP as kinetic energy.

Ans. 40%

2. In aerobic respiration, 1 gram mole glucose is oxidised to liberate ……… of energy.

Ans. 686 kral

3. …………. respiration results in muscle fatigue.

Ans. Anaerobic

4. The source of heat energy, which is released during combustion of coal, is ……….. energy.

Ans. Solar

5. ………. is also called controlled combustion.

Ans. Respiration

6. ……….. is the first compound of Krebs cycle.

Ans. Citrate

7. The enzyme ATP-ase is present in the ……….. of mitochondria.

Ans. Oxysome

8 Respiration is a/an ……….. reaction.

Ans. Exothermic

9. ………. is a fast and uncontrolled process.

Ans. Combustion

10. Pyruvate is the end product of glycolysis which gets converted into ………

Ans. Acetyl Co-A

State True or False

1. Respiration is a physico-chemical reaction.

Ans. False

2. Aerobic respiration occurs is presence of free molecular oxygen.

Ans. True

3. Methanobacterium sp. is an anaerobic bacterium.

Ans. True

4. Fermentation occurs in yeast.

Ans. True

5. Bacteria named Lactobacillus lactis produce ethanol by the process of fermentation.

Ans. False

TOPIC – 3

NUTRITION

SUMMARY

Nutrition is a combination of processes, by which living organisms obtain the substances necessary for growth, developing resistance against diseases and acquiring potential energy for life by intake of food, digestion, absorption, assimilation and egestion (in animals) or by synthesis and assimilation (in plants).
The two important modes of nutrition include. (i) Autotrophic nutrition and (ii) Heterotrophic nutrition.
In Autotrophic nutrition, the plants and other photosynthetic organisms prepare their own food with the help of sunlight, water and carbon dioxide.
The animals cannot prepare their own food. Therefore they have to rely on other animals or plants for nutrition. This is known as heterotrophic nutrition.
The different modes of heterotrophic nutrition include: Parasitic, Saprophytic, Symbiosis, Holozoic, etc.
Holozoic nutrition is the mode of heterotrophic nutrition that involves ingestion, digestion, absorption, assimilation and egestion of food material. Example-Human, animals and insectivorous plants.
In some cases, two different plants live in close association and are mutually benefited by that association. This mode of nutrition is called symbiotic nutrition.
Saprophytic type of nutrition depends on non-living substances. Food and decaying organic material are absorbed through bodywall of the organism. Example-Bactería, Fungi.
Parasitic mode of nutrition depends on another living organism (Host). It has close association with the host and obtains food form it. Host is not benefited but harmed. Example-Bacteria, fungi, plants like Cuscuta and animal like tapeworm.
The human digestive system or alimentary system is mainly made up of three parts-(i) alimentary canal, (ii) accessory organs, (iii) digestive glands
Alimentary canal consists of mouth, vestibule, oral cavity, pharynx, oesophagus, stomach, small intestine and large intestine.

Long Answer Type Questions

1. Mention the different types of plant nutrition with examples.

Ans. Different types of plant nutrition with examples

Plants perform nutrition in different ways, which are mentioned below.

Autotrophic nutrition: In this process, plants perform nutrition by synthesising their own food from simple inorganic matters by photosynthesis followed by assimilation of the simple sugars produced in this process.
Example-All green plants, certain blue-green algae or cyanobacteria, protists like Euglena, Chrysamoeba and photosynthetic bacteria like Rhodopseudomonas, Rhodospirillum etc.
Heterotrophic nutrition: The plants which cannot carry out photosynthesis due to the lack of photosynthetic pigments. and depend on other living or dead or decaying organic matter for food, are called heterotrophs. Their mode of nutrition is called heterotrophic nutrition. Different types of heterotropic nutritions are discussed below.
1. Parasitic nutrition: In this process, some plants grow on other plants (called hosts) and draw nutrition from them.
  Example-Plants like Cuscuta, Rafflesia, etc. show parasitic nutrition.
2. Saprophytic nutrition: In this process, some plants draw nutrition from dead organisms and decaying organic matters.
  
  Example-All types of fungi, like Agaricus, Mucor, Penicillium etc. perform saprophytic nutrition.
3. Symbiotic nutrition: In some cases, two different plants live in close association and are mutually benefited by that association. This mode of nutrition is called symbiotic nutrition.
  Example-Lichen is a symbiotic association of algae and fungi. Here, the fungal part provides the settling platform and water to the algal part. In return, the algae synthesise and supply food.
4. Insectivory: Certain plants draw nitrogenous nutrients from small insects. These plants have special organs, typically modified for trapping insects. This mode of nutrition is called insectivory.
  Example-Pitcher plant, sundew, bladderwort are some plants which show insectivory.

2. Why animal nutrition is also called heterotrophic nutrition? Briefly describe different types of animal nutrition.

Ans. Reason behind animal nutition to be called heterotrophic nutrition

Animals cannot synthesise their own food from simple inorganic materials like CO₂ and water. For nutrition, they depend on other organisms. They depend on plants or other organisms for their food. As animals depend on other organisms for food their mode of nutrition is called heterotrophic nutrition.

Different types of animal nutrition

The following types of nutrition are found in animals-

1. Parasitic nutrition: Some animals draw nutrients from other living organisms (hosts), thereby benefiting itself and harming the other. This mode of nutrition is called parasitic nutrition.

Example-Tape worm, round worm, Plasmodium etc. live inside the body of the host and are called endoparasites.Lice,ticks etc. live on the body surface of the host and are called ectoparasites.

2. Saprozoic nutrition: Some animals draw nutrients from decaying organic matter.This mode of nutrition is called saprozoic nutrition.

Example-Earthworm,Amphitrite (a marine annelid) show saprozoic nutrition.

3. Symtiotic nutrition: Sometimes, two organisms develop a close association between them, from which both are nutritionally benefited. This type of nutrition is called symbiotic nutrition.

Example-E. coli gets shelter and food in human intestine.In return, they synthesise vitamin.

4. Coprophagy: Faeces of many animals contain nutritionally important substances.Some animals draw nutrients by consuming their own faeces, or of other animals. This type of nutrition is called coprophagy.

Example-Rabbits, guinea pigs, dung beetles etc. show coprophagy.

5. Sanguinivory: Some animals draw nutrients from blood of other animals. This mode of parasitic nutrition is called sanguinivory.

Example-Auchmeromyia (blood sucking maggot), leeches, vampire bats etc. show this type of nutrition.

3. Briefly discuss the different phases of holozoic nutrition.

Ans. Phases of holozoic nutrition

Holozoic nutrition involves five different phases, which are mentioned below.

Ingestion: In this step, food materials are taken into the mouth, chewed by teeth and are pushed into the food pipe or oesophagus. Besides teeth, tongue also helps in this process. Salivary secretion makes the food bolus softer to facilitate this process.
Digestion: This step involves mouth, stomach, liver, pancreas and small intestine. Several enzymes are secreted inside these organs from the glandular cells. In the presence of water, these enzymes act upon respective food materials and help in the breakdown of the matters into simple and absorbable forms. This step is known as hydrolysis or digestion of food.
Absorption: Mainly small intestine is involved in this process. Stomach and large intestine also play some role in it. End products of digestion are taken into the blood capillaries, where they are absorbed.
Assimilation: All tissues of the body are involved in this process. In this penultimate phase of holozoic nutrition, various nutritionally important compounds and ions, absorbed in the blood from GI tract, enter into cells and become a part of the protoplasm.
Egestion: This process involves the rectum and anus of large intestine. In this last phase, undigested food matters are temporarily stored and then discharged as faeces.

4. Briefly describe the structure of human alimentary canal.

Ans. Structure of human alimentary canal

The long tube or passage extending from mouth to anus through which food passes during digestion is called the alimentary canal. It is composed of the following parts-

Mouth: It is the opening of the alimentary canal, guarded by a pair of lips. The inner chamber is known as the buccal cavity, which consists of a muscular tongue at the base. The cavity also consists of an upper and a lower jaw, fitted with a maximum of 32 teeth (16 on each jaw).
Pharynx: It is slightly swollen, muscular chamber behind the buccal cavity.
Oesophagus: It is a straight, vertical, muscular tube, that carries food from the pharynx to the stomach.
Stomach: It is J-shaped muscular sac, present on the left side of the upper abdominal cavity. It consists of four regions-the cardiac stomach (upper portion, close to the heart), fundic stomach (wide middle portion), the body (portion between fundic stomach and pyloric stomach) and pyloric stomach (lower portion, attached to duodenum).
Small intestine: It is a very long, narrow and highly convoluted tube, that extends from the stomach to the large intestine and occupies maximum portion of the abdominal cavity. It has three portions-duodenum (emerging from stomach), jejunum (the middle region) and ileum (meets the large intestine).
Large intestine: This tube is less coiled and broader than small intestine. It consists of three partscaecum (the dilated portion, where small intestine meets), colon (the tubular part consisting of four regions-ascending colon, transverse colon, descending colon and sigmoid colon), rectum (a wide tube, next to the sigmoid colon, that proceeds downward and opens through the anus).

5. How does absorption of digested food matters occur in the human GI tract? Briefly explain the method of assimilation of nutrients in the human body.

Ans. Method of absorption of food

Absorption mainly occurs in the small intestine. The inner wall of the intestine develops many small finger-like projections called villi (singular-villus). Each villus has a central lymph duct called lacteal, and a few blood capillaries. Monosaccharides, amino acids and glycerol are absorbed in the blood capillaries. Fatty acids are taken into the lacteals. Besides small intestine, a few materials are absorbed through the epithelial lining of the stomach and large intestine. These include water, alcohol, few salts and drugs.

Method of assimilation of food

From the intestine, blood carries glucose, fructose, amino acids and a few fatty acid molecules to liver, through hepatic portal vessels. After supplying nutrients in the liver, this blood moves to systemic circulation. Lymph ducts carry simple fat molecules and finally transfer them to systemic circulation. As a result, all nutrients reach every tissue and cell through blood. Finally, these essential molecules are incorporated in the protoplasm of the cells.

6. Briefly explain the fate of the nutrients in a living cell. Mention the features of a balanced diet.

Ans. Fate of nutrients in a living cell rice,

The absorbed nutrients get assimilated within the cells and carry out different functions.

Monosaccharides participate in the cellular respiration as respiratory substrates. These are oxidised to generate energy, which is necessary for different life activities. Proteins help in building body cells and lipids are kept as stored matters. Vitamins act as coenzymes and minerals act as cofactors of various enzymes, or as fundamental components of some cellular molecules. Almost all end products of digestion undergo necessary changes within the cells by the process of metabolism.

Features of a balanced diet

Foods, that we take everyday, do not always make a balanced diet. Moreover, sugar Balanced diet any single food material cannot be treated as a balanced diet. It should have certain features which are as follows-[1] It should help to maintain the growth and perfect shape of the body. [2] It should perfectly meet the calorific demand of a body. [3] It should help to develop resistance against infection.

7. What do you understand by the term mechanical digestion? Mention the different types of mechanical digestion.

Ans. Mechanical digestion

The process by which dry and semi-solid foods are converted into smaller fragments in the G1 tract and also the process by which the food is pushed forward along the GI tract, is called mechanical digestion.

Different types of mechanical digestion

Generally mechanical digestion is of three types-

Mastication or chewing: Food matters taken into the buccal cavity undergo mechanical processing. Different types of teeth help to cut, tear and masticate the food matters into small particles. Saliva moistens it to form a soft and smooth dough-like matter. This whole process is known as mastication or chewing of food.
Swallowing: The process by which the food passes from the mouth to the pharynx and then enters the oesophagus by shutting the epiglottis, is known as swallowing or deglutition.
Movements of the GI tract: Movements of the gastro-intestinal tract occur which help in the forward movement of food. Generally two types of movements are seen-peristalsis and segmentation movement.

8. Describe the different phases of protein digestion with the help of a suitable schematic diagram.

Ans. Different phases of protein digestion

Digestion of protein occurs stepwise, mostly in the stomach and small intestine. Several proteolytic enzymes (enzymes that break down protein) influence the process of protein digestion. The different phases of protein digestion are as follows-

Digestion in the buccal cavity: Since no proteolytic enzyme is present in the buccal cavity, protein digestion does not occur here.
Digestion in the stomach: This is the site where protein digestion starts. Upon entering the stomach, the food is converted into chyle after it gets mixed with the gastric juice secreted from the gastric glands of the stomach. Presence of HCl in the gastric juice, makes the chyle acidic and activates the proteolytic enzyme pepsin. Pepsin converts proteins into peptones. However, pepsin is unable to execute the complete digestion of proteins into peptones and therefore, incomplete digestion of proteins occur in the stomach.
Digestion in the small intestine: Upon entering the small intestine, the undigested proteins and peptones mix with the pancreatic and the enteric juices. Proteolytic enzymes, named trypsin and chymotrypsin present the pancreatic juice hydrolyse peptones and undigested proteins into small peptides. After that, these small peptides are broken down into amino acids by the action another enzyme, called erepsin, which is present in the enteric juice. These amino acids are then absorbed into the blood with the help of villi present in the small intestine.

9. Explain the different steps of carbohydrate digestion with the help of a suitable schematic diagram.

Ans. Different steps of carbohydrate digestion

Carbohydrate digestion occurs mainly in the buccal cavity and in the small intestine.

Digestion in the buccal cavity: Carbohydrates specially boiled starch’ present in the food, mix with Ptyaline present in the salivary juice and is converted to maltose and isomaltose. Maltase present in saliva converts maltose into 2 molecules of glucose. The quantity of maltase in the saliva is very low and therefore, small amounts of glucose is formed in the buccal cavity by the action of the salivary enzymes.
Digestion in the stomach: Digestion of carbohydrates does not occur in the stomach due to absence of amylolytic or carbohydrate digesting enzymes. Only a small amount of sucrose is hydrolysed into glucose and fructose with the help of HCl.
Digestion in the small intestine: In the small intestine, both boiled and unboiled starch get converted into maltose by the action of pancreatic amylase. Maltase present in enteric juice then breaks down maltose into 2 molecules of glucose. Majority of the ingested starch is broken down by pancreatic amylase. But if any portion of the starch is still left unbroken, then intestinal amylase will act on it to break it down into simpler components. Moreover, intestinal lactase and sucrase hydrolyse lactose into glucose and galactose and sucrose into glucose and fructose respectively. In this way, complex carbohydrates are broken down into simple monosaccharide units which are then absorbed in the body.

Short Answer Type Questions

1. What is nutrition?

Ans. Nutrition is a combination of processes, by which living organisms obtain the substances necessary for growth, developing resistance against diseases and acquiring potential energy for life by intake of food, digestion, absorption, assimilation and egestion (in animals) or by synthesis and assimilation (in plants).

2. Write the relationship between respiration and nutrition.

Ans. Nutrition is the process of obtaining food by the organism and digesting the complex nutrients in the food. In respiration, the energy present in the food (taken in through nutrition) is released and used to carry out different metabolic process.

3. What do you mean by nutrients?

Ans. The components of food that provide nourishment to the body is called nutrients.

Example-Carbohydrate, protein, vitamin etc.

4. What is food?

Ans. The edible matters, which a living organism consumes for growth, replenishing physical loss, developing resistance against diseases and acquiring energy for performing all life activities, are called food.

5. All foods are nutrients but all nutrients are not food-Explain.

Ans. All substances required for the overall nutrition and metabolism of the body, either directly or indirectly, are known as nutrients. Among them only the energy yielding nutrients such as carbohydrates, proteins and fats are generally considered as food. The others such as vitamins, mineral salts and water are incapable of yielding energy but are essential for growth, developing resistance against diseases, replenishing physical loss and thus, are called protective nutrients. Therefore, we can say that all foods are nutrients but all nutrients are not food

6. What is meant by autotrophic nutrition?

Ans. The nutrition in which green plants and other phototrophic or chemoautotrophic organisms synthesise their own organic food from inorganic matters within their body cells is called autotrophic nutrition.

7. What is meant by heterotrophic nutrition?

Ans. The nutrition in which organisms take in complex organic or inorganic matters as food, digest it before absorption and assimilation or absorb organic matters from dead and decaying plant and animal products is called heterotrophic nutrition.

Example-All animals and non-photosynthetic plants perform heterotrophic nutrition.

8. What is meant by holophytic nutrition?

Ans. The physiological process in which autotrophic organisms perform nutrition by synthesising their own food and assimilating it within the body is called holophytic nutrition.

Example-All green plants and photosynthetic organisms perform this type of nutrition.

9. What is meant by holozoic nutrition?

Ans. The physiological process, which involves intake of complex organic or inorganic matter as food, followed by their digestion, absorption of endproducts of digestion, assimilation of essential nutrients within the protoplasm and finally egestion of undigested matters, is called holozoic nutrition. Example-All animals perform holozoic nutrition.

10. What is meant by symbiotic nutrition?

Ans. The nutritional process where two different organisms depend upon each other to get nutrition and in this process both are benefited, is called symbiotic nutrition. Example-Rhizobium forms symbiotic relationship with roots of legumes.

11. Explain the mutually beneficial association (symbiosis) of lichen.

Ans. The most famous example of symbiotic mode of nutrition is of a lichen, an organism which has a chlorophyll containing partner alga and a fungus. The fungus helps in providing minerals, water and shelter to the alga. The alga uses the things provided by fungus and has chlorophyll in itself which helps in the process of photosynthesis.

12. What is meant by coprophagy?

Ans. The faeces of animals contain a number of nutrients. Certain animals get these nutrients by consuming its own faeces or of other animals. This type of nutrition is called coprophagy. Example- Guinea pigs, rabbits consume their own faeces whereas pigs and dung beetle consume faeces of others to perform this type of nutrition.

13. What is caecotrophy?

Ans. Certain mammals like rabbits, guinea pigs, etc. eject the semi-digested food of the caecum in the form of faeces or pellets, and engulf it again for complete digestion. This type of nutritional process is called caecotrophy.

14. What is sanguinivory?

Ans. Certain animals perform nutrition by sucking blood from warm-blooded animals, this type of nutrition is called sanguinivory. ExampleMosquitoes, leeches, bedbugs, vampire bats perform this type of nutrition.

15. Mention the function of human tongue?

Ans. Human tongue has many taste buds on it to taste different food. The taste buds at the tip are for tasting sweet food. The lateral buds are for tasting salty and sour food. The buds at the posterior region of tongue are for tasting bitter food. Besides tasting food, tongue helps in movement of food inside mouth to mix it with saliva. Tongue also helps in swallowing the bolus. It also takes part in articulation of speech.

16. What is saliva? What is its source?

Ans. Saliva: Saliva is colourless, tasteless, viscid digestive juice secreted from the salivary glands in the mouth cavity.

Source: Its sources are parotid, submaxillary and sublingual salivary glands.

17. How many types of salivary glands are found in human body? Mention their location.

Ans. There are three pairs of salivary glands in human mouth-[1] Parotid gland-Located at the base of the ears. [2] Sub-maxillary or submandibular gland-Located on two sides of lower jaw. [3] Sublingual gland-Located below the tongue under the floor of mouth.

18. What is pharynx? Mention its function.

Ans. Pharynx: The posterior portion of the buccal cavity from where larynx and oesophagus start, is called pharynx.

Function: Pharynx helps in the flow of bolus into oesophagus and the passage of inspired and expired air through larynx.

19. Briefly mention the structure of stomach.

Ans. Human stomach is a ‘J’ shaped highly extensible muscular sac. The upper portion of it, approaching the heart, is called the cardiac end. The body of stomach is known as fundus. The posterior end, approaching duodenum is called the pyloric end. Inner wall of stomach has many longitudinal ridges, called rugae.

20. Mention the role of HCl in stomach.

Ans. Role of HCl in stomach are as follows-[1] HCl, secreted from oxyntic cells of the stomach wall, activates pepsinogen to active pepsin which helps in protein digestion. [2] HCl helps in the hydrolysis of sucrose inside the stomach. [3] HCl kills many germs, which enter into the stomach with the food.

21. Mention the functions of stomach.

Ans. The functions of stomach are as follows[1] Stomach holds the food for some time. [2] HCl secreted from the stomach acidifies the food to kill germs, which enter along with it. [3] HCl activates inactive proenzymes to active enzymes.

22. What is peristalsis?

Ans. A wave of contraction and relaxation movement proceeds all along the alimentary tract from oesophagus to rectum. This typical movement is called peristalsis.Peristalsis pushes the contents of the GI tract downwards.

23. Write a brief description of human colon.

Ans. Colon is the wider tube situated at the posterior portion of the human GI tract. It has four portions ascending colon, transverse colon, descending colon and sigmoid colon. The ascending arm emerges from the base of the caecum and the sigmoid colon ends at rectum. Colon is the site of water absorption and the formation of faeces from the undigested food.

24. Give a brief structural account of human liver.

Ans. Liver is the largest gland of the human body. It is a dark reddish brown coloured triangular gland with two distinct lobes. Liver is lodged at the right side of the abdominal cavity just below the diaphragm. A club-shaped, thin-walled gall bladder is present on the lower side of the right hepatic lobe.

25. Mention the functions of human liver.

Ans. The functions of human liver are as follows[1] Alkaline bile, secreted from liver, neutralizes acidic chyme from stomach. [2] Bile salts emulsify fat to facilitate its digestion. [3] Bile helps in the absorption of fat. [4] Kupffer cells of liver kill germs by phagocytosis.

26. What is common bile duct?

Ans. Hepatic ducts from right and left lobes of liver join to form a common hepatic duct. The cystic duct from the gall bladder comes to unite with the common hepatic duct to form a wider descending bile duct, called common bile duct.

27. Mention the functions of pancreas.

Ans. The functions of pancreas are as follows[1] Pancreas secretes both enzymes and hormones. Pancreatic juice contain amylolytic, lipolytic and proteolytic enzymes, which help in the hydrolysis of carbohydrate, fat and proteins respectively. [2] From a and B cells of islets of Langerhans two important hormones are secreted, which are glucagon and insulin respectively. These two hormones jointly regulate the sugar level of blood.

Very Short Answer Type Questions

Multiple Choice Questions & Answers [MCQ]

1. By nutrition-

A. Potential energy is converted into kinetic energy

B. Kinetic energy is stored in the cells

C. Heat is generated in the body

D. Dry weight of the body increases

Ans. D

2. Function of food is-

A. Generation of energy

B. Maintaining body growth

C. Prevention of diseases

D. All of these

Ans. D

3. Select the correct statement.

A. Nutrition always depends upon digestion

B. Digestion is a type of nutrition

C. Nutrition is none other than digestion

D. Digestion is a step of nutrition

Ans. D

4. Select the correct statement.

A. All foods need digestion before assimilation

B. Assimilation of food is unnecessary for green plants as they synthesise ready food

C. Assimilation is the most essential part of any nutrition

D. All are correct

Ans. D

5. Assimilation is a step of nutrition, by which-

A. Complex food is converted into simple absorbable form

B. Essential nutrients get integrated into the protoplasm

C. Nutrients are taken in by body fluid from the digestive tract

D. Blood supply nutrients to the tissue

Ans. B

6. Green plants perform nutrition by-

A. Photosynthesis and absorption

B. Photosynthesis and digestion

C. Photosynthesis and assimilation

D. Photosynthesis and egestion

Ans. C

7. Parasitic nutrition is seen amongst-

A. Some fungi

B. Cuscuta

C. Louse

D. All of these

Ans. D

8. Similarity between Rafflesia and Puccinia is that, both are-

A. Parasitic organisms

B. Saprophytic plants

C. Autotrophic plants

D. Partial autotrophs

Ans. A

9. Lichen is a-

A. Saprophytic fungus

B. Symbiotic association of algae and fungi

C. Parasitic fungus

D. None of these

Ans. B

10. Insectivorous plants depend on insects for-

A. Phosphorus

B. Iron

C. Nitrogen

D. Calcium

Ans. C

11. Mycorrhiza is a symbiotic association between plant root and-

A. Bacteria

B. Algae

C. Fungus

D. None of there

Ans. C

12. Parasitic organisms always show-

A. Close association

B. Nutritional interdependence

C. Benefit of themselves

D. Benefit of both members

Ans. C

13. Escherichia coli helps in the synthesis of vitamin B_₁2 in our intestine.

This is a case of-

A. Autotrophism

B. Heterotrophism

C. Symbiosis

D. Competition

Ans. C

14. Coprophagy is a typical nutritional technique, seen among-

A. Few cattle

B. Few rodents

C. Most herbivores

D. Few carnivores

Ans. B

15. Sanguinivores include-

A. Mosquitoes

B. Mosquitoes and vampire bats

C. Leeches and bedbugs

D. All of these

Ans. D

16. The aerial roots found in the orchids, which help in the absorption of water vapour, is called-

A. Haustoria

B. Velamen

C. Villus

D. None of these

Ans. B

17. Carrion feeding is shown by-

A. Cattle

B. Crow

C. Pigeon

D. Cat

Ans. B

18. Mammals are heterodont because they-

A. Possess similar type of teeth

B. Have different types of teeth

C. Show teething twice in life

D. Have socketted teeth

Ans. B

19. Similarity between saliva and gastric juice is-

A. Both kill bacteria

B. Both help in fat digestion

C. Both help in carbohydrate digestion

D. Both help in protein digestion

Ans. A

20. Hydrolytic enzymes help in-

A. Digestion

B. Absorption

C. Assimilation

D. Diffusion of food

Ans. A

Answer in a single word or sentence

1. Which physiological process provides potential energy to living organisms?

Ans. Nutrition provides potential energy to living organisms.

2. Which two steps are involved in the nutrition of green plants?

Ans. Photosynthesis and assimilation are involved in the nutrition of green plants.

3. What is the similarity between Rafflesia and louse?

Ans. Both Rafflesia and louse are parasitic in nature.

4. In which type of nutrition is one member benefited at the expense of another?

Ans. In parasitic nutrition one member is benefited at the expense of the another.

5. What is the similarity between dung beetle and pig?

Ans. Both dung beetle and pig show coprophagy.

6. What is the nutritional dissimilarity between louse and tapeworm?

Ans. Louse is an ectoparasite but tapeworm is an endoparasite.

7. In which nutritional association both associates are benefited?

Ans. In symbiotic nutrition both associates are benefited.

8. Why do some plants capture insects for nutrition?

Ans. Some plants capture insects to fulfill the nutritional needs of nitrogen.

9. By which process does food bolus reach stomach through oesophagus?

Ans. Food bolus reaches the stomach through oesophagus by peristalsis.

10. Which acid makes the chyme acidic inside stomach?

Ans. HCl makes the chyme acidic inside stomach.

11. From which cells HCl is secreted in stomach?

Ans. HCl is-secreted from oxyntic cells of inner lining of the stomach.

12. Which is the widest portion of the human GI tract?

Ans. Large intestine or colon is the widest portion of the human GI tract.

13. Which cells secrete digestive enzymes in small intestine?

Ans. Digestive enzymes are secreted from Brunner’s gland cells inside the small intestine.

14. Which portion of human GI tract is responsible for absorption of excess water from residue of digestion?

Ans. Colon is responsible for the absorption of excess water from the residue of digestion.

15. From which gland is ptyaline secreted?

Ans. Ptyaline is secreted from the salivary glands.

16. On which substrate does ptyaline act?

Ans. Ptyaline acts upon boiled starch.

17. Which digestive enzymes prefer lower pH to act properly?

Ans. Pepsin and gastric lipase prefer lower pH to act properly.

18. Which proteolytic enzyme is secreted from the pancreas?

Ans. Trypsin is a proteolytic enzyme, secreted from the pancreas.

19. Which is the primary centre for protein digestion?

Ans. Stomach is the primary centre for protein digestion.

20. Which, other than digestive enzymes, are secreted from pancreas?

Ans. Other than digestive enzymes, hormones like insulin and glucagon are secreted from the pancreas.

21. Which cells in stomach secrete digestive enzymes?

Ans. The peptic cells or chief cells in the stomach, secrete digestive enzymes.

22. Name an enzyme, which prefers neutral or slightly alkaline pH for better action.

Ans. Trypsin prefers neutral or slightly alkaline pH for better action.

23. Which type of food is not digested in the stomach?

Ans. Starch is not digested in the stomach.

24. Which type of carbohydrate is hydrolysed in stomach?

Ans. Sucrose is hydrolysed in the stomach.

25. Which enzyme hydrolyses protein into peptone?

Ans. Pepsin hydrolyses protein into peptone.

26. Which enzyme hydrolyses fats into fatty acids and glycerol?

Ans. Lipases hydrolyse fat into fatty acids and glycerol.

27. Which intestinal enzyme hydrolyses lower peptides into amino acids?

Ans. Erepsin hydrolyses lower peptides into amino acids.

28. What is the function of lipids in blood?

Ans. Lipids help to dissolve and transport vitamin A, D, E and K in blood.

29. Which digestive juice is alkaline in nature?

Ans. Bile is alkaline in nature.

30. What is bile comprised of?

Ans. Bile is comprised of water, various inorganic salts, bile salts, bile pigments, fatty acids, cholesterol etc.

31. Name the bile salts.

Ans. Sodium taurocholate and sodium glycocholate are the bile salts.

Fill in the blanks

1. Growth and ……….. are two anabolic processes.

Ans. Nutrition

2. Autotrophic nutrition is a type of ………. nutrition.

Ans. Holophytic

3. Heterotrophic nutrition involves ………. steps.

Ans. Five

4. Sundew (Drosera) is a ………. plant.

Ans. Insectivorous

5. Haustoria is a ……….

Ans. Sucking root

6. Agaricus performs ……….. type of nutrition.

Ans. Saprophytic

7. Mycorrhiza is located in the root of ………..

Ans. Pine

8. ………. engulfs food with the help of pseudopodia.

Ans. Amoeba

9. Hydra engulfs food with the help of ………….

Ans. Tentacles

10. We can taste sweet with the taste buds placed at ……… of our tongue.

Ans. Tip

11. Teeth appears twice in a lifetime of man. Such type of dentition is called ……..

Ans. Diphyodont

12. There are ……… salivary glands in human mouth.

Ans. Six

13. The part of the alimentary canal to which appendix is attached, is the ……….

Ans. Caecum

14. HCl is produced in the …………

Ans. Stomach

15. Gall bladder is located beneath the ………. lobe of liver.

Ans. Right

State True or False

1. During photosynthesis anabolism occurs.

Ans. True

2. Lichen is an example of symbiotic association between algae and fungi.

Ans. True

3. Blue-green algae are capable of synthesising their own food by photosynthesis.

Ans. True

4. A symbiotic bacterium Rhizobium sp. synthesises vitamin B₁2 in human intestine.

Ans. False

5. There are three pairs of salivary glands, namely parotid, sub-maxillary and sublingual glands.

Ans. True

6. Oesophagus is a 10-12 cm long tube, which comes down vertically from the base of pharynx to the stomach along the mid chest line.

Ans. True

7. One of the functions of liver is to kill germs by phagocytosis.

Ans. True

8. Bile acts in the acidic pH of stomach.

Ans. False

9. Bile juice contains different enzymes that help in the emulsification of fats.

Ans. False

10. Ptyaline acts on boiled proteins.

Ans. False

TOPIC – 4

CIRCULATION

SUMMARY

The circulatory system constitutes the transportation of nutrients, excretory products, metabolites, hormones, water etc., to and from the tissues and organs all over the body.
Human circulatory system is made up of heart, blood vessels and blood. The blood vessels are of three types-arteries, veins and capillaries.
Heart contracts and relaxes rhythmically and pumps blood.
Circulatory system are of two types-(i) Open circulatory system (ii) Closed circulatory system.
In open circulatory system, the blood is not confined to blood vessels and flows freely in the body cavity and channels known as lacunae and sinuses in the tissues. In closed circulatory system, the blood flows through blood vessels only.
Body fluids are of two types—(i) Extracellular (Blood, lymph, etc) (ii) Intracellular.
Blood is comprised of plasma and blood corpuscles.
Landsteiner discovered the four blood groups—A, B, AB and O. There is another system of blood grouping based on Rh factor.
The process by which blood is coagulated in the haemorrhage site, is called blood coagulation.

Long Answer Type Questions

1. Define circulation and mention the importance of circulation in living organisms.

Ans. Circulation

Circulation is the physiological process by which nutrients, respiratory gases, hormones and metabolic waste matters are transported within a body through a fluid medium.

Importance of circulation

Circulation is important for the living organisms as it plays the following roles-

Movement of nutrients and minerals: Water, essential minerals, food materials are transported to all tissues of a living body by means of circulation.
Transport of respiratory gases: Respiratory gases, such as O₂ and CO₂, are transported within the body through the process of circulation.
Removal of metabolic wastes: The unwanted matters, produced in the cells from metabolic activities are transported from the tissues to excretory organs for elimination.
Movement of synthesised materials: Hormones, synthesised in cells, are transported to their target organs by means of circulation.
Maintenance of heat: Circulatory fluid maintains the body heat in warm-blooded animals. 6 Storage: Amino acids are stored in the circulatory fluid (blood) to form an amino acid pool. Some lipids (cholesterol) are also stored in the blood.

2. Schematically mention different types of blood corpuscles of human body.

Ans. Different types of blood corpuscles or cells of human body

3. Mention the functions of lymph, cerebrospinal fluid and sweat.

Ans. Functions of lymph

The functions of lymph are as follows-[1] It supplies nutrients and oxygen deep into the tissues, [2] Lymphocyte cells and antibodies present in the lymph, kill germs, [3] Absorbs fat from the intestine, [4] It collects the metabolic wastes from the tissue fluid, [5] Lymph maintains pressure, volume and composition of the tissue fluids.

Functions of cerebrospinal fluid

The functions of cerebrospinal fluid are mentioned below.

[1] Acts as a shock absorber for the brain & spinal cord, [2] Supplies nutrition and oxygen to the brain tissue, [3] Helps in the removal of metabolic wastes from the CNS.

Functions of sweat

The functions of sweat are as mentioned below.

[1] It maintains the acid-base balance, water balance and the body temperature.

[2] Some salts, urea and many other materials are excreted through sweat.

4. Define plasma and briefly discuss the composition of plasma.

Ans. Plasma

Plasma is the yellowish, slightly alkaline, transparent watery matrix of blood.

Composition of plasma

Plasma contains water (91-92%) and solid matters (8-9%). These solid matters include different inorganic and organic materials.

1. Inorganic matters of plasma (0.9%): Compounds of sodium, potassium, calcium, magnesium, phosphorus, iron, copper, chlorine, iodine, etc.

2 Organic matters of plasma (7-8%): Organic matters of plasma are mentioned below.

[A] Sugar-glucose

[B] Protein-serum albumin, serum globulin, prothrombin, fibrinogen, etc.

[C] Fat-cholesterol, lecithin, phospholipids, neutral fat molecules.

[D] Non-protein nitrogenous compounds-urea, uric acids, ammonia, creatinine, creatine, etc.

[E] Pigments-bilirubin, biliverdin, ß-carotene etc.

[F] Secreted materials-hormones, enzymes etc.

[G] Gases-oxygen, carbon dioxide etc.

5. Mention the functions of blood plasma? How is water utilised in human body?

Ans. Functions of blood plasma

The functions of blood plasma are-[1] Plasma helps in transportation of nutrients, metabolic waste matters, hormones, etc. [2] It maintains acid-base balance of the body. [3] Plasma proteins develop immunity and provide protection against many diseases. [4] Plasma proteins, like prothrombin and fibrinogen, help in blood clotting.

Utility of water in human body

Water is utilised in the human body in different ways which are as follows-[1] Water acts as the main component of the protoplasm. [2] It helps in the hydrolysis of food matters in digestion. [3] Water acts as the medium of diffusion and osmosis for nutrients, respiratory gases, metabolic wastes and hormones.

6. Briefly describe the role of blood in human body.

Ans. Functions of blood in human body

For human life, blood is an ultimate essentiality. We need blood for-

Transportation of O₂, CO₂ and nutrients: Blood carries O₂ and nutrients to different tissues and carries CO₂ to lungs.
Removal of the metabolic wastes: Blood collect excretory matters from the tissues and carries those materials to respective excretory organs.
Movement of hormones from glands to target organs: Hormones, secreted from the endocrine glands are transported to the tissues or other glands by blood.
Maintenance of body temperature: Blood carries glucose to all the tissues, which generate heat by oxidation to maintain the body temperature.
Resistance against infections: Neutrophils and monocytes kill germs by phagocytosis. Lymphocytes produce antibody. Thus, blood resists infection.
Preventing blood loss: Excessive loss of blood from wounds is restricted by its coagulating ability.

7. Explain the significance of blood grouping. How do you inspire somebody for blood donation?

Ans. Significance of blood grouping

Due to the presence of various agglutinogens and agglutinins, transfusion is not possible among all groups. If donor’s and recipient’s blood react to cause agglutination (antigen-antibody reaction i.e., clumping of RBCs), their blood groups will be treated as mismatch or incompatible. There will be no agglutination if the blood groups are compatible. In case of incompatible transfusion, agglutinogen of donor’s RBC reacts with agglutinin of recipient’s plasma to cause agglutination.

Ways to inspire somebody for blood donation

To inspire somebody for blood donation, I shall try to eliminate his on her misconceptions regarding blood donation by saying that-[1] Blood donation causes no harm to the donor. [2] The donated blood is replenished within a week. [3] Blood donation reduces the chance of heart attack and hypertension. [4] Blood can not be created artificially. So, in certain emergency situations, donated blood can save a patient’s life. [5] It is a noble gesture of a person towards the society.

8. Briefly describe the course of circulation through human heart.

Ans. Course of circulation through human heart

Human heart beats spontaneously in a rhythmic fashion. Due to this contraction and expansion, blood is pumped through the blood vessels and circulates throughout the body. The contraction and expansion of the heart is called systole and diastole respectively. During systole and diastole following events occur in different chambers of the heart.

Diastole of auricles: In this phase the auricles expand and auriculoventricular valves close. Pressure decreases in the auricles. Soon deoxygenated blood from superior and inferior vena cava and coronary sinus enters into right auricle. At the same time oxygenated blood from pulmonary veins enters into left auricle.
Systole of auricles: As the auricles get completely filled, they contract. Pressure increases in the auricle. With this pressure, both tricuspid and bicuspid valves open towards right and left ventricles respectively.
Diastole of ventricles: Diastole of ventricles starts with the systole of auricles. With the opening of tricuspid and bicuspid valves deoxygenated blood enters into right ventricle and oxygenated blood rushes into left ventricle respectively.
Systole of ventricles: When the two ventricles get filled with blood, ventricular systole starts. So pressure increases inside these chambers. With this pressure tricuspid and bicuspid valves close with a jerk. With maximum ventricular pressure the pulmonary and aortic valves open at a time. Then deoxygenated blood from right ventricle and oxygenated blood from left ventricle are pumped out through pulmonary trunk and aorta respectively.
In human heart, blood flows through two separate circuits. The right portion of it carries deoxygenated blood and oxygenated blood flows through the left portion. In a normal human heart, mixing of two different types of blood never happens. Therefore, human heart acts as a perfectly double circuit heart.

9. Draw a line diagram of L.S. of human heart to show the course of circulation through it, with labelling.

Ans. Diagram of human heart

Following is a labelled diagram of L.S. of human heart showing course of circulation through it.

10. What is meant by double circulation? Show the path of double circulation with a schematic diagram.

Ans. Double circulation

In higher vertebrates like birds and mammals, heart is four chambered. Here blood flows in two separate circuits, one through systemic path and the other through pulmonary path. This type of circulation is known as double circulation. It is called a double circulatory system, since it has two loops. The one is from the heart to the lungs and the other is from the heart to the rest of the body.

Diagram of the path of double circulation

The following labelled diagram shows the path of double circulation.

11. What is Rh blood group system? State its significance.

Ans. Rh blood group system

Rh blood group system is based on Rh factor which was discovered by Landsteiner and Weiner (1940). In this system, blood is grouped on the basis of the presence or absence of a special agglutinogen or antigen called ‘Rh factor’ in the RBC. This antigen was first observed in Rhesus monkey. Human blood having RBCs bearing Rh factor is called Rh positive (+) and blood without Rh factor is called Rh negative (–).

Significance

If blood of a Rh positive donor is introduced into Rh negative recipient’s body then anti-Rh factor is formed in recipient’s blood within 12 days. If then, the same donor’s blood is introduced into the same recipient’s body second time, then the donor’s RBCs are agglutinated in recipient’s body. As a result the recipient suffers from damage. So, it is essential to match donor’s and recipient’s blood before transfusion.

Short Answer Type Questions

1. What is meant by circulation?

Ans. Circulation is the physiological process by which nutrients, respiratory gases, hormones, minerals, etc., are supplied to all the tissues of the body and the metabolic waste matters, produced inside the cells are transported to the respective excretory organs through fluid medium.

2. What is heart?

Ans. Heart is a muscular, multi-chambered (2 in fishes, 3 in amphibians and reptiles, 4 in birds and mammals and 13 in insects) sac-like structure, which continuously pumps blood in a rhythmic manner into arteries and receives blood from the veins and in this process, helps the blood to flow through the network of vessels to every part of the human body.

3. What are arteries?

Ans. Arteries are thick-walled blood vessels with roundish lumen, which carry oxygenated blood (exception: pulmonary arteries) from heart to the tissues with continuous rhythmic pulsation.

4. What are veins?

Ans. Veins are the blood vessels with thinner wall and flattish lumen, which carry deoxygenated blood (exception: pulmonary vein) from the tissues to the heart and possess valves to maintain unidirectional blood flow.

5. What are capillaries?

Ans. Capillaries are the finest of blood vessels with very thin wall, present in between arteries and veins. These fine vessels reach deep in the tissues to supply nutrients, oxygen, etc., to the tissue fluid through diffusion and to collect the excretory materials and hormones from the tissues and the glands respectively.

6. What is meant by circulatory system?

Ans. The system of organs, involved in supplying nutrients, respiratory gases, hormones to different tissues of the body and removing metabolic wastes from the body, is known as circulatory system.

7. What is meant by open circulation?

Ans. The type of circulation, where body fluid does not remain confined within vessels, but pumped by the heart into open body cavity (haemocoel) to come in direct contact with the tissues, is called open circulation. This type of circulation is seen in molluscs, arthropods, etc.

8. What is meant by closed circulation?

Ans. The type of circulation, where blood flows through heart and network of blood vessels and never opens in the body cavity, is called closed circulation. This type of circulation is noticed in all vertebrates and a few invertebrates like earthworm, leech, etc.

9. What is blood?

Ans. Blood is a red coloured, thick, faintly salty and alkaline, opaque, vascular connective tissue, composed of different types of cells suspended in a liquid matrix (plasma), which is pumped by the heart to flow through vessels for the transport of nutrients, respiratory gases, hormones, excretory substances and several other materials to all parts of the body.

10. What is haemolymph?

Ans. Haemolymph is a colourless fluid, composed of a watery matrix and a few cells, flowing through the body cavity (haemocoel) of insects and other arthropods.

11. What is lymph?

Ans. Lymph is a yellowish, transparent, modified tissue fluid, involved in absorption and transportation of nutrients, dissolved gases, immunologically important materials and different secretory and excretory substances into the tissues of higher animals.

12. Where do you find lymph in human body?

Ans. Lymph is present in lymph vessels and lymph glands. Lymph glands are localised in certain regions of the human body viz., around neck, breasts, armpits, groin, etc.

13. What is CSF? Where is it found?

Ans. CSF: CSF or cerebrospinal fluid is a typical fluid, present in the central nervous system (CNS) of vertebrates.

Occurrence of CSF: CSF is present in the ventricles of brain and in the central canal of the spinal cord. This fluid is also present in the subarachnoid space (between the second and third covering layers of brain or meninges).

14. What is synovial fluid? What does it do?

Ans. Synovial fluid: Synovial fluid is a slightly viscous, colourless body fluid typically present in the membrane-bound synovial cavities in between movable bone joints.

Function: Synovial fluid protects bone ends against frictional damage and supplies nutrients.

15. What is tissue fluid? What is its function in animal body?

Ans. Tissue fluid: Tissue fluid is the extracellular fluid present in the tissues of multicellular animals.

Function: Tissue fluid helps in the transportation of nutrients, respiratory gases, hormones and metabolic waste materials.

16. What is meant by cytosol?

Ans. Cytosol is a bulk of intracellular fluid present in the cytoplasm. Different types of intracellular fluids are present in different cell organelles like mitochondria, Golgi body, plastid, endoplasmic reticulum, lysosome, vacuoles, etc., performing. their respective functions.

17. How is water utilised in human body?

Ans. Water is utilised in the human body in different ways as follows-[1] It acts as the main component of the protoplasm, [2] Helps in hydrolysis of food matters during digestion, [3] Acts as the medium of diffusion and osmosis for nutrients, respiratory gases, metabolic wastes and hormones.

18. Mention the functions of RBC.

Ans. Functions of RBC are as follows-[1] RBCs transport respiratory gases. [2] They help to maintain acid-base balance in the plasma. [3] They are involved in maintenance of ionic equilibrium. [4] They also help in colouration of faeces.

19. From where do RBCs originate in human body?

Ans. RBCs originate from-[1] Vasculosa region of early embryo. [2] Spleen and liver of matured foetus, about one month before birth and [3] Red bone marrow after birth.

20. Mention the structural features and function of neutrophils.

Ans. Structural features: Neutrophils are amoeboid WBC with a diameter of 10-12 um. Its cytoplasm is granular and the nucleus has 2-7 lobes.

Function: Neutrophils kill germs by the process of phagocytosis.

21. What is meant by universal donor?

Ans. Due to absence of agglutinogen in RBC, a person having blood group ‘O’ can donate blood to any group. In this case, chance of haemagglutination does not arise. Therefore, an individual having blood group ‘O’ is called universal donor.

22. What is meant by universal recipient ?

Ans. Due to absence of any agglutinin in plasma, people having blood group ‘AB’ can receive blood from any blood group. In this case, chance of haemagglutination does not arise. Therefore, an individual having blood group AB’ is called universal recipient.

23. What is Rh factor?

Ans. Rh factor is an antigenic protein present in the RBC of most of the world’s population, which has close similarity with a factor present in RBC of the monkey Rhesus macaques. The people having this factor are treated as Rh+ whereas those not having it are regarded as Rh^–.

24. Mention the importance of Rh factor in blood transfusion.

Ans. If a person without Rh factor (Rh^–) is transfused with blood from a person carrying Rh factor (Rh⁺), then after 12 days, an antibody, called anti-Rh factor, develops in the recipient’s blood. If the same person gets a second transfusion with Rh+ blood, then a reaction will take place between Rh factor (antigen) and anti-Rh factors (antibody) in his or her blood. This will lead to a fatal consequence due to agglutination and haemolysis of RBC.

25. What is erythroblastosis foetalis?

Ans. If an Rh mother carries a Rh⁺ foetus, the Rh antigen enters into mother’s blood from the foetus. In this situation, anti-Rh factor (antibody) develops in mother’s blood, which comes back to Rh⁺ foetus and destroys the foetal RBC. As a result, the baby is born with serious anaemia. This is called erythroblastosis foetalis.

26. What is meant by blood transfusion? Mention its importance.

Ans. Blood transfusion: Blood transfusion is a technique of intravenous infusion of blood to a person who is deficient of blood or blood components.

Importance: Blood is something, which cannot be prepared by any means. Therefore, a patient, suffering from severe anaemia or excessive blood loss has to be transfused with blood to replenish the need.

27. What is meant by blood clotting? Mention its importance.

Ans. Blood clotting: Blood clotting is a physiochemical process by which blood turns into a semisolid jelly-like mass or clot.

Importance: Blood clots at the opening of a wound within a few minutes, thereby, stops bleeding and prevents excessive blood loss.

28. Mention different layers of the the wall of human heart.

Ans. The wall of heart has three layers. These are-[1] Epicardium (outermost layer), [2] Myocardium (middle layer) and [3] Endocardium (innermost layer).

29. What is mitral valve? What does mitral valve do?

Ans. Mitral valve: Mitral valve or bicuspid valve is the double cusped valve present at the left atrioventricular opening of the human heart.

Function: Mitral valve allows blood to flow from left atrium to left ventricle but prevents its backflow.

30. What is tricuspid valve? What does it do?

Ans. Tricuspid valve: Tricuspid valve is the triplecusped valve present at the right atrioventricular opening of the human heart.

Function: Tricuspid valve allows blood to flow from right atrium to right ventricle but prevents the backflow.

Very Short Answer Type Questions

Multiple Choice Questions & Answers [MCQ]

1. Which of the following statements is incorrect?

A. By circulation metabolic wastes are carried to the excretory organs

B. By circulation metabolic wastes are expelled from the body

C. Blood carries oxygen as a compound

D. Blood keeps our body warm

Ans. B

2. The components of circulatory system are –

A. Lungs, heart, kidney

B. Blood vessels and blood

C. Blood and lymph

D. Heart, blood vessels, blood and lymph

Ans. D

3. Blood vessels include-

A. Arteries

B. Veins

C. Arteries and veins

D. Veins, arteries and capillaries

Ans. D

4. Normal human heart beats-

A. 5720 times/hr.

B. 4320 times/hr.

C. 6720 times/hr.

D. 72 times/hr.

Ans. B

5. Heartbeat is controlled by the —

A. Activity of cardiac muscle

B. Activity of cardiac muscles and special connective tissues

C. Activity of cardiac muscles, special connective tissues and central nervous system

D. Activity of cardiac muscles and central nervous system

Ans. C

6. Human blood is red due to-

A. A respiratory pigment

B. An excretory material

C. A photosynthetic pigment

D. None of these

Ans. A

7. Haemoglobin and haemocyanin are similar, because both-

A. Are non-protein pigments

B. Are metallo-protéins

C. Carry iron

D. Carry copper

Ans. B

8. Artery carries blood from-

A. Heart to body parts

B. Body parts to heart

C. Lungs to heart

D. None of these

Ans. A

9. Haemolymph and haemocoel are the components of circulatory system of-

A. Crab

B. Earthworm

C. Cockroach

D. Starfish

Ans. C

10. Haemocoel is a-

A. Chamber of insect heart

B. Chamber of earthworm heart

C. Body cavity filled with haemolymph

D. None of these

Ans. C

11. Pericardial sinus is present in cockroach-

A. Around the heart

B. Around the gut

C. Around the nerve cord

D. Inside head

Ans. A

12. Largest sinus of insect haemocoel is-

A. Pericardial sinus

B. Perivisceral sinus

C. Perineural sinus

D. Cephalic sinus

Ans. B

13. Cockroach heart has-

A. 13 chambers

B. 25 openings

C. 24 ostia

D. All of these

Ans. D

14. Blood from cockroach’s theheart first reaches the-

A. Pericardial sinus

B. Perivisceral sinus

C. Perineural sinus

D. Cephalic sinus

Ans. D

15. Closed circulatory system does not possess-

A. Artery

B. Vein

C. Haemocoel

D. Heart

Ans. C

16. Blood from heart to lungs passes through-

A. Pulmonary vein

B. Pulmonary artery

C. Systemic artery

D. Carotid artery

Ans. B

17. Body fluid includes-

A. Blood and lymph

B. Blood, lymph and cerebrospinal fluid

C. Urine, blood and lymph

D. All of these

Ans. B

18. Select the wrong statement.

A. Intracellular fluid is called cytosol

B. Blood is an intracellular fluid

C. Urine is an extracellular fluid

D. Cerebrospinal fluid is an extracellular fluid

Ans. B

Answer in a single word or sentence

1. Which components of human circulatory system do act as vehicle?

Ans. Blood and lymph

2. Which gases are transported through blood?

Ans. Oxygen and carbon dioxide

3. Which type of secretory products are transported through blood.

Ans. Hormones are the main secretory products, transported through blood.

4. What does pulse rate indicate?

Ans. Pulse rate indicates the rate at which the heart beats.

5. In which type of circulation different organs bathe in blood?

Ans. In open circulatory system different organs bathe in blood.

6. From which body cavity does blood enter into the heart of a cockroach?

Ans. Blood enters into the heart of a cockroach from the pericardial sinus.

7. Why does blood of earthworm appear red?

Ans. Blood plasma of earthworm contains haemoglobin, so it appears red.

8. Which the largest sinus of insect body?

Ans. Visceral sinus

9. How many ventricles does insect heart possess?

Ans. Insect heart possesses thirteen ventricles.

10. Name an invertebrate animal, which possesses closed circulatory system.

Ans. Earthworm

11. Name an animal, in which blood does not take part in the transportation of the respiratory gases.

Ans. Cockroach

12. Name a nutritionally important plasma protein.

Ans. Albumin

13. Name an immunologically important plasma protein.

Ans. Globulin

14. Which disease is caused due to deficiency of red blood cells?

Ans. Anaemia

15. Which part of human circulatory system has the highest immunological importance?

Ans. Lymph glands

16. Which type / types of blood can be transfused to a person carrying ‘O’ blood group?

Ans. A person with ‘O’ blood group can receive the ‘O’ group of blood only.

17. Which is the largest cell in the human blood?

Ans. Monocyte (Diameter. 12-18 μm)

18. Which is the smallest cell in human blood?

Ans. Platelet (Diameter. 2.5 μm)

19. Which blood cells of human blood prevent blood coagulation inside blood vessels?

Ans. Basophils

20. Which are the non-nucleated cells of the human blood?

Ans. Platelets and matured red blood cells

21. Which blood cells of human blood take part in antibody formation?

Ans. Lymphocytes

22. Increase of which blood cell indicates blood cancer?

Ans. Excessive and uncontrolled increase of WBC indicates blood cancer.

23. Who discovered the ABO blood grouping technique?

Ans. Dr. Karl Landsteiner

24. A baby is suffering from erythroblastosis foetalis. His father carries Rh⁺ blood. Which type of blood is expected in his mother?

Ans. Mother of the baby is expected to carry Rh^– blood.

25. Which blood cell prevents allergy?

Ans. Eosinophils prevent allergy.

26. Which blood cells are involved in transportation of respiratory gases?

Ans. Erythrocytes (RBC)

27. Which blood cell is the most abundant in human blood?

Ans. RBC is the most abundant in human blood.

28. Which blood coagulating factor is possessed by platelets?

Ans. Thromboplastin

29. Which element is essential for activating thromboplastin?

Ans. Calcium

30. Which two valves are commonly called semilunar valves?

Ans. Aortic valve and pulmonary arterial valves

31. How many heartbeats are generated by a healthy sinoatrial node?

Ans. 70-80 heartbeats per minute.

32. Which junctional tissue supplements the function of a defective SA node?

Ans. AV node or atrioventricular node

33. How long does RBC survive?

Ans. Normal life span of RBC is 120 days.

Fill in the blanks

1. By means of ……….. fluid, excretory matters from tissues are transported to the excretory organs.

Ans. Circulatory

2. Other than cholesterol, lecithin which is a ………. is also present in plasma.

Ans. Fat

3. Only ……….. blood passes through the venous heart of fish.

Ans. Deoxygenated

4. The matrix of blood is known as ………..

Ans. Plasma

5. The outer layer of blood vessels is known as ……….

Ans. Tunica adventitia

6. ………. valve is present at the right atrioventricular opening of human heart.

Ans. Tricuspid

7. The unit by which human blood pressure is measured, is mm of ………

Ans. Hg

8. An adult human body contains ……… litres blood.

Ans. 5

9. ……… is present between artery and vein.

Ans. Capillary

10. Artery possesses no ……….

Ans. Valve

11 Body cavity of insects containing blood is called ………

Ans. Haemocoel

12. ………. is present inside the ventricles of the brain.

Ans. CSF

13. ………. is present in joints.

Ans. Synovial fluid

State True or False

1. Lymph is a special tissue fluid.

Ans. True

2. Haemocyanin is present in the body of prawn.

Ans. True

3. Bicuspid valve is present at right atrioventricular opening.

Ans. False

4. Some invertebrates contain haemoglobin in RBC.

Ans. False

5. Veins carry blood towards the heart.

Ans. True

6. Thrombocytes contain bilobed nucleus.

Ans. False

7. Due to blood donation donor becomes sick.

Ans. False

8. Karl Landsteiner was the person who discovered Rh factor.

Ans. True

9. Blood can be created artificially.

Ans. False

TOPIC – 5

EXCRETION

SUMMARY

Excretion is the physiological process of separation and removal of water soluble waste products produced due to cellular metabolism and the organs responsible for producing, collecting and removing metabolic wastes from the body are called excretory products.
Removal of metabolic wastes takes place either by eliminating them from the body or by storing them in the form of suspension and crystals (in case of plants).
There is no excretory organs or system in plants. Excretory products of plants are not so harmful and more simple than animals.
Mechanism of excretion in plants are-shedding of leaves (hog palm, silk cotton) shedding of barks (guava,arjun), shedding of fruits (lemon, apple, tamarind), etc.
Other organisms have different types of excretory organs to eliminate waste materials from their body. Such as contractile vacuoles (Amoeba,Euglena), flame cells (flatworms), nephridia (earthworm, leech), malphigian tubule (insects), kidney (vertebrates).
The human excretory system consists of a pair of kidneys, a pair of ureters, one urinary bladder and one urethra.
Nephron is the structural and functional unit of kidney. It has two parts-Malpighian corpuscles and renal tubule. Malpighian corpuscles consists of glomerulus and Bowman’s capsule. Renal tubule has three parts–proximal convoluted tubule, loop of Henle and distal convoluted tubule.
Urea is the main excretory material of our body which is eliminated through urine.Ammonia is converted into urea in liver.
Nephrons play a very important role in the process of urine formation.The different steps of urine formation, i.e. ultrafiltration, selective reabsorption and tubular secretion, take place within the different parts of the nephron.
The accessory excretory organs in human are skin, lungs, liver etc.

Long Answer Type Questions

1. What is the significance of excretion?

Ans. Significance of excretion

Excretion is an important physiological process which helps to lead a healthy life. Its significance is discussed in the next section.

Maintenance of fit and healthy life: Excretion removes all toxic and harmful matters produced in the cells by various metabolic activities.
Maintenance of water balance: Excretion removes excess water from the cells to maintain water balance in the body.
Recycling of matters: By excretion, many elements, present in the waste materials, are disposed in nature. These are made available for reuse by action of decomposers.
Economic importance: Many plant excretory products, especially alkaloids, have certain medicinal importance. Gums, resins, tannins, latex etc. are used for industrial purposes. Some nitrogen-rich animal excretory products are used as fertilisers.

2. How do plants dispose excretory materials?

Ans. Excretion in plants

Plants eliminate excretory products by the following processes.

Shedding of leaves: Trees, such as hog palm, Albizia, silk cotton etc. store excretory substances in leaves. These trees shed leaves once a year to dispose those excretory substances.
Exfoliation of barks: Some trees, such as guava, arjun etc. deposit waste matters in their bark. These plants naturally peel off their bark to eliminate those waste matters from time to time.
Shedding of fruits: Plants like lemon, apple, tamarind etc. store excretory matters, like different organic acids (e.g. citric acid, tartaric acid, malic acid, etc.) or essential oils in their fruits. These are removed from these plants by shedding of fruits.
Shedding of flowers: In some plants, excretory products are stored in their flowers. These products are excreted when different parts of the flowers are shedded off. Example-Clove flower.
Alkaloids: Sometimes alkaloids are stored in the stems and leaves of some plants like banyan, Calotropis etc. In alkaloids different types of excretory products remain solubilised. In case of injury, these alkaloids are released outside and in this way other soluble excretory products are also released.
Resin secretion: In the resin ducts of stem and leaves of some plants, like pine, a complex insoluble excretory product called resin is present.
Gum excretion: In some plants such as babul, soluble wastes are excreted in the form of gum.
Excretion of water: Potato, tomato etc. solubilise different excretory products in water and then excrete them with the help of hydathodes.

3. Briefly describe the structure of human excretory system.

Ans. Structure of human excretory system

Human excretory system consists of a pair of kidneys, two ureters, a urinary bladder and a urethra.

Kidneys: The kidneys are brown coloured, bean-shaped structures, positioned at either side of vertebral column, just below the ribs. The concave face of the kidney is called the pelvis. The section of kidney shows two distinct regions-outer cortex and inner medulla. A renal artery enters and a renal vein leaves each kidney through the pelvis. Numerous fine tubular structures, called nephrons, are present in kidneys, which filters blood from the specially designed renal capillaries.
Ureter: Ureters are two in number. Each ureter is a 35 cm long, slightly curved tube, emerging from the renal pelvis. Ureters are usually 2-4 mm in diameter. The ureters connect kidneys to the urinary bladder, present at the lower portion of the abdominal cavity.
Urinary bladder and urethra: Urinary bladder is a muscular sac, located at the front lower portion of the abdominal cavity. Urethra is a muscular tube that descends from the floor of the bladder. The base of urethra is equipped with sphincter muscles, which help to hold the urine inside urinary bladder. Urine enters the urinary bladder via the ureters and leaves via urethra. The capacity of a typical human bladder is 300-500 ml.

4. Briefly describe the structure of nephron with diagram.

Ans. Structure of nephron

A nephron has two parts-malpighian corpuscles and renal tubule.

Malpighian corpuscles: It is situated at the free and blind end of a nephron. This portion is composed of Bowman’s capsule and glomerulus. The free and blind end of nephron forms a cup-shaped doublewalled structure, called the Bowman’s capsule. A fine branch of renal artery enters into the Bowman’s capsule as afferent arteriole. It ramifies to form a capillary network inside the capsule, where these capillaries reunite and return as efferent arteriole. It is comparatively narrower than the afferent arteriole. This capillary network is called glomerulus.
Renal tubule: It is a convoluted tubule, extending from the base of the Bowman’s capsule and ending in the collecting tubule. Renal tubule has three partsproximal convoluted tubule, which starts from the base of the Bowman’s capsule; loop of Henlewhich is a ‘U’-shaped loop-like structure, and distal convoluted tubule, which ultimately meets comparatively wider collecting tubule. Several collecting ducts finally unite to form thicker ductscalled the duct of Bellini.

5. Describe the steps of urine formation in human kidney.

Ans. Steps of urine formation in human kidney

The mechanism of urine formation in nephron involves four different phases, which are mentioned below.

Glomerular ultrafiltration: Due to increased blood pressure in the glomerular capillaries, water from blood plasma enters into Bowman’s capsule. This water carries different excretory materials like urea, uric acid, etc. and many essential substances like glucose, amino acids, smaller protein molecules, salts, ions, vitamins, etc. This process is known as glomerular ultrafiltration and the dilute fluid, collected in the Bowman’s capsule, is called glomerular filtrate.
Reabsorption: Glucose and different ions (K⁺, Na⁺ etc.) are reabsorbed in cells of renal tubule from the glomerular filtrate by active transport. Cells of proximal convoluted tubules reabsorb the small protein molecules by phagocytosis. Ions like phosphates, bicarbonates, chlorine, etc., vitamín C, amino acids and many other substances are reabsorbed by renal tubule. All these reabsorbed essential materials then return to the blood.
Secretion: Creatine, creatinine, hippuric acid, etc. are some excretory materials, which are secreted from the renal tubule.
Passive absorption of water: Excess water from the glomerular filtrate is reabsorbed by passive transport in the loop of Henle and distal convoluted tubule. Reabsorption of water is controlled by a posterior pituitary hormone, named Antidiuretic Hormone (ADH). After these four steps, normal concentrated urine is formed in nephron, which is received by the collecting tubule and finally reach the duct of Bellini.

Short Answer Type Questions

1. What is meant by excretion?

Ans. Excretion is the process by which harmful metabolic waste products are eliminated from the body of an organism in order to keep it fit and healthy.

2. What are excretory products? Give example.

Ans. Excretory products: The metabolic wastes which are eliminated from the body and cannot be stored inside are called excretory products.

Example: Latex, alkaloid (plant); urea, ammonia (animal).

3. Why faeces is not an excretory product?

Ans. Faeces is not directly formed from the major organs responsible for excretion (liver, kidneys, lungs and skin) and hence is not a result of metabolic reactions. That is why, faeces not an excretory product.

4. How does excretion help in maintaining water balance in a living body?

Ans. Due to the deposition of waste matters, osmotic pressure in cells changes. As a result, more water enters into the cells, that hampers their normal biological processes. By excretion, waste matters are eliminated from the cells along with water. Thus, excretion helps to maintain water balance and osmotic pressure within cells and tissues of a living body.

5. How are the metabolic wastes of plants eliminated?

Ans. In plants, some metabolic wastes are stored in specialised cells or tissues, that are eliminated during any physical injury. Some other excretory matters are deposited in organs like leaves, fruits, barks, which plants shed naturally.

6. Name some nitrogenous and non-nitrogenous excretory products of plants.

Ans. Excretory products of plants are-

[1] Nitrogenous or alkaloids: (i) Nicotine (ii) Daturine (iii) Quinine (iv) Reserpine (v) Caffeine.

[2] Non-nitrogenous: (i) Gum (ii) Resin (iii) Latex (iv) Tannin.

7. Mention the source and medicinal importance of atropine.

Ans. Source: Leaves and roots of Atropa belladonna. Medicinal importance: [1] It is used to dilate the pupil before ophthalmological investigation. [2] It also used to treat certain inflammatory conditions of the eye.

8. What is tannin? What are its sources?

Ans. Tannin: Tannin is a bitter tasting carbon-rich material excreted by plants.

Sources of tannin: Tea leaves, haritaki, bohera fruits, stems of Acacia catechu,etc.

9. Mention the economic importance of gum.

Ans. The economic importances of gum are as follows-[1] Gum is used as glue in book-binding industry. [2] It is used as a fixative of lime-based paints, inks and water-based paints. [3] Gums of some plants are used to prepare chocolates.

10. Mention the economic importance of latex.

Ans. The economic importances of latex are as follows-[1] Latex of rubber plants is the raw material used in industrial rubber, which is used to prepare all rubber material starting from vehicle tyres to pencil erasers. [2] Latex of papaya plant is a source of the protein-digesting enzyme-papaine. [3] Latex of Brosimum galactodendron is consumed as supplement of milk.

11. Mention the economic importance of resin.

Ans. The economic importances of resin are as follows [1] Hard resin is used as a sealing material. [2] Liquid resin is used to prepare turpentine oil. [3] Asafoetida is used as an essence for cuisines. [4] Resin of sal is used to as ‘dhuna’.

12. Mention the economic importance of tannin.

Ans. The economic importances of tannin are as follows-[1] It is used in tannery to tan leather. [2] Tannin is used to prepare certain type of ink. [3] It is used as ‘kattha’ or ‘khair’ in betel leaf.

13. Mention the economic importance of essential oil or volatile oil.

Ans. The economic importances of essential oil are as follows-[1] It is used to prepare essence for soap, body or hair oil and several other cosmetic items. [2] Essential oil is used to add flavour to different preparations of sweets. [3] Essential oil obtained from eucalyptus is used in pain balms.

14. What are raphides?

Ans. Raphides are sharp needle-shaped crystals of calcium oxalate found in various tissues including leaves, roots, shoots, fruits etc. of wide varieties of plant species and are typically kept in highly specialized cell called idioblast.

15. What is cystolith?

Ans. Cystolith is a botanical term for outgrowths of the epidermal cell wall, usually of calcium carbonate, formed in a cellulose matrix in special cells called lithocysts, generally in the leaf of plants.

16. How do animals dispose excretory matter?

Ans. In animals, toxic excretory products are transported from tissues to specific excretory organs by circulatory system. From these organs, metabolic wastes are eliminated from the body.

17. Write about ammonotelic animals with example.

Ans. Ammonotelic animals eliminate ammonia as excretory product. These animals are aquatic in Sponges, jellyfish, echinoderms, freshwater bony fishes, larvae of amphibians are ammnotelic animals. nature.

18. Write about uricotelic animals with examples.

Ans. Uricotelic animals excrete uric acid. Uric acid is least toxic and can be stored within cell. Insects, lizards, snakes, birds are uricotelic animals.

19. Write about ureotelic animals with examples.

Ans. Animals excreting urea are called ureotelic. A large among of water is required to excrete urea as it is more toxic than uric acid. It is found in cartilaginous fish, some bony fish, adult amphibians and mammals.

20. Mention the role of nephridium in excretion

Ans. Nephridium is the excretory organ of annelids, such as earthworm, leech, etc. Each nephridium (plural nephridia) has three portions–nephritides, tubule and nephridiopore. Nephrostome is a ciliated funnel-shaped end of nephridium, which collects metabolic wastes from coelomic fluid. The coiled tubule collects excretory substances from surrounding blood capillaries. All these materials are then released outside through nephridiopore, present on the skin.

21. Name the different parts of nephron.

Ans. Each nephron is made up to two main parts; Malpighian body (renal corpuscle) and renal tubule. Malpighian body comprises a cup-shaped Bowman’s capsule and a mesh-work of blood capillaries, the glomerulus.

22. Mention the location of brush border. State its funciton.

Ans. Brush border:Proximal convoluted tubule (PCT) is made of single layer of cubical epithelial cells with brush-bordered microvilli.

Function: It reabsorbs glucose, amino acids from glomerular filtrate.

23. Mention the location and function of Henle’s loop.

Ans. Henle’s loop: The second part of the renal tubule takes straight course down the medulla, where it doubles round and comes up again to the cortex in the form of an ‘U’-shaped loop which consists of ascending and descending loop.

Functions: [1] It reabsorbs nest of glucose and bicarbonate. [2] It also reabsorbs water in descending segment and Na⁺ in ascending segment.

24. Mention the functions of nephron.

Ans. [1] Filtration of non-colloidal parts of plasma. [2] Reabsorption of different useful substances like glucose, water, salt, amino acids etc. [3] Tubular secretion of some unwanted substances like sulphur compounds, organic acids, creatinine etc. [4] Synthesis of new substances like benzoic acid, H⁺ ions, hippuric acid, inorganic phosphate, ammonia etc.

25. What do you mean by urine?

Ans. Urine is a straw yellow or amber coloured, weakly acidic watery solution of excretory products with aromatic odor formed in the nephron of kidney.

Very Short Answer Type Questions

Multiple Choice Questions & Answers [MCQ]

1. One objective of excretion is-

A. Disposal of metabolic waste matters

B. Disposal of excess water

C. Disposal of unwanted salts

D. All of these

Ans. D

2. Plants dispose their excretory matters by

A. Shedding leaves

B. Shedding fruits

C. Exfoliation of bark

D. All of these

Ans. D

3. A non-nitrogenous plant excretory matter is-

A. Reserpine

B. Caffeine

C. Daturine

D. Tannin

Ans. B

4. A nitrogenous plant excretory product is-

A. Latex

B. Tannin

C. Resin

D. Theine

Ans. A

5. ‘Dhuna’ is a …….. secreted from sal tree.

A. Gum

B. Resin

C. Alkaloid

D. Olio resin

Ans. D

6. Camphor is a-

A. Gum

B. Resin

C. Alkaloid

D. Olio resin

Ans. B

7. A latex producing plant is-

A. Pine

B. Calotropis

C. Mango

D. Both B and C

Ans. B

8. Papain is secreted from –

A. Pea

B. Papaya

C. Pumpkin

D. Potato

Ans. D

9. Rauvolfia is the source of-

A. Quinine

B. Reserpine

C. Morphine

D. Tannin

Ans. D

10. Which is used as a strong pain killer?

A. Daturine

B. Quinine

C. Tannin

D. Morphine

Ans. D

11. Which of the following is used as a nerve soother and blood pressure regulator?

A. Reserpine

B. Morphine

C. Caffeine

D. Tannin

Ans. A

12. Excretory organ of unicellular organism is-

A. Lysosome

B. Contractile vacuole

C. Endoplasmic reticulam

D. Golgi body

Ans. B

13. Flame cells are seen in-

A. Tapeworm

B. Earthworm

C. Round worm

D. Caterpillar

Ans. A

14. Nephridia open outside the body through-

A. Nephrostome

B. Nephridiopore

C. Excretory pore

D. Anus

Ans. B

15. Malpighian tubule is associated with the excretory system of –

A. Tapeworms

B. Earthworms

C. Insects

D. Starfishes

Ans. C

16. Outer covering of human kidney is popularly known as-

A. Pericardium

B. Pleura

Renal cortex

D. Capsule

Ans. D

Answer in a single word or sentence

1. Name a tree, which removes excretory materials by exfoliation of bark.

Ans. Guava tree removes excretory materials by exfoliation of bark.

2. Name a plant, which stores most of its excretory matters in leaves.

Ans. Tea plant stores most of its excretory matters (tannin, theine) in leaves.

3. Name a medicinally important plant, which disposes its excretory matters through bark.

Ans. Arjun (Terminalia arjuna) tree disposes its excretory matters through bark.

4. Which economically important material is excreted from Hevea brasiliensis?

Ans. Latex of Hevea brasiliensis is the economically important excretory material used to prepare commercial rubber.

5. Name a water-soluble non-nitrogenous excretory material of plant.

Ans. Gum is a water-soluble excretory material of plant. non-nitrogenous

6. Which part of Rauvolfia plant is the source of reserpine?

Ans. Root of Rauvolfia plant is the source of reserpine.

7. From which part of cinchona plant is quinine extracted?

Ans. Quinine is extracted from the bark of cinchona plant.

8. What is the source of atropine?

Ans. Leaves and roots of Atropa belladonna are the sources of atropine.

9. Which type of plant excretory matters are insoluble in water but most have great medicinal importance?

Ans. Alkaloids are insoluble in water but most have great medicinal importance.

10. Name the plant whose excretory material is used for preparing varnish.

Ans. Excretory material of pine tree is used for preparing varnish.

11. Name an edible plant excretory matter.

Ans. Camphor is an edible plant excretory matter.

12. Name a plant excretory matter used as a common nerve stimulant.

Ans. Caffeine is used as a common nerve stimulant.

13. Which alkaloid is used to control hypertension?

Ans. Reserpine is used to control hypertension.

14. Name the excretory organ of Amoeba.

Ans. Contractile vacuole is the excretory organ of Amoeba.

15. Which is the excretory organ of annelids?

Ans. Nephridia is the excretory organ of annelids.

16. From where do malpighian tubules collect excretory materials?

Ans. Malpighian tubules collect excretory materials from haemolymph.

17. What is the excretory organ of prawn called?

Ans. The excretory organ of prawn is called green gland or antennary gland.

18. What is the structural and functional unit of kidney called?

Ans. The structural and functional unit of kidney is called nephron.

19. Which is the site of ultrafiltration in a nephron?

Ans. Malpighian corpuscle is the site of ultrafiltration in a nephron.

20. Which portion of human excretory system stores urine for sometime inside the body?

Ans. Urinary bladder stores urine for sometime inside the body.

21. In which organ of vertebrate animals is urine produced?

Ans. Urine is produced in the kidneys of vertebrates.

22. Which branch of artery forms the glomerulus?

Ans. Afferent renal arteriole forms glomerulus. the

23. Which arteriole comes out from the glomerulus of nephron?

Ans. Efferent renal arteriole comes out from the glomerulus of nephron.

24. Which region of kidney possesses more number of nephrons?

Ans. Cortical region of kidney possesses more number of nephrons.

25. Name two materials which are reabsorbed in blood from renal tubule.

Ans. Amino acids and glucose are two materials reabsorbed in blood from renal tubule.

26. Name a vitamin which is reabsorbed from glomerular filtrate to blood.

Ans. Vitamin C is reabsorbed from glomerular filtrate to blood.

27. Name a hormone, which controls the reabsorption of water from renal tubule.

Ans. Antidiuretic hormone or ADH controls the reabsorption of water from renal tubule.

28. Name an excretory material, which is disposed through faeces.

Ans. Bilirubin is excreted through faeces.

29. Which main excretory material is eliminated through lungs?

Ans. Carbon dioxide is the main excretory material, eliminated through lungs.

30. Through which glands are the fatty excretory materials eliminated from human body?

Ans. The fatty excretory materials of human body are eliminated through sebaceous glands of the skin. *

31. How much glomerular filtrate is produced in the two kidneys of a healthy adult individual in 24 hours?

Ans. In 24 hours, about 170 L of glomerular filtrate is produced in the two kidneys of a healthy adult individual.

32. How much urine is excreted by a healthy adult individual in 24 hours?

Ans. In 24 hours, a healthy adult individual excretes about 1.5 L of urine.

Fill in the blanks

1. A flavour adding plant product, asafoetida is a ……….

Ans. Resin

2. ……… is the plant excretory product present in apples.

Ans. Malic Acid

3. A latex, named …….. is used as a digestive enzyme.

Ans. Papain

4. Source of nicotine is ……… of tobacco.

Ans. Leaf

5. Plant released organic acids through …………

Ans. Shedding of fruits

6. ……… is used for production of the medicine for asthma.

Ans. Daturine

7. Reserpine is obtained from the root of ………

Ans. Rauwolfia plants

8. The excretory organ of Planaria is ………

Ans. Flame cell

9. Ammonia is the chief nitrogenous excretory material in ………

Ans. Fresh water fishes

10. ………. is the primary excretory organ of the human body.

Ans. Kidney

11. The base of urethra is equipped with ………. muscles, which help to hold the urine inside urinary bladder.

Ans. Sphincter

12. Minor calyx is located at …………

Ans. Kidney

State True or False

1. Resin of pine is used as a fixative of lime based paints.

Ans. False

2. Alkaloids are soluble in water but insoluble in ethyl alcohol.

Ans. False

3. Coffee is obtained from seeds of Coffea arabica plant.

Ans. True

4. Paramoecium carries out excretion by forming contractile vacuoles.

Ans. True

5. The concave face of the kidney is called pelvis.

Ans. True

6. The afferent renal arteriole comes out of the Bowman’s capsule.

Ans. False

7. Creatine and creatinine are secreted from the proximal convoluted tubule.

Ans. False

8. A nephron has 2 parts-malpighian tubule and renal tubule.

Ans. False

9. In cockroach, malpighian tubules absorb nitrogenous haemolymph. waste matters from

Ans. True

10. In liver fluke, the entire excretory matter is disposed finally through excretory pore.

WNA24

WBBSE 9th Class Science Solutions Life Science & Environment Chapter – 3 Physiological Processes of Life

West Bengal Board 9th Class Science Solutions Life Science & Environment Chapter – 3 Physiological Processes of Life

WBBSE 9th Class Life Science & Environment Solutions

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