WBBSE 10th Class Science Solutions Science & Environment Chapter 1 Control and Co-ordination in Living Organisms

SUMMARY

• Control of different function and co-ordination between them is regulated by hormone i.e. hormone helps in plant response.
• Hormone regulates the apical growth of stem and root, lateral growth, flowering, bud formation, germination of seed in plants. Hormone thus control different types of growth and germination in plants.
• The main three hormone in plants are auxin, gibberellin and cytokinin.
• Auxin is an organic acid with indole ring and nitrogen. It control the apical dominance through increasing apical bud formation, cell division, root formation and its growth and also control the tropic movement.
• Gibberellin is a terpenoid organic acid without nitrogen. It breaks the dormancy of bud and seed, increase the growth of internode, increase fruit size, etc.
• Cytokinin is an organic, alkaline, purine derivative without nitrogen. It increases cell division, promote lateral dominance (opposite to auxin), etc.
• Artificial auxin, gibberellin, cytokinins are applied in agriculture.

Long Answer Type Questions

1. Apical and lateral growth: Primary growth of any plant occurs at the apex of stem and root. This growth makes the shoot taller and the roots longer. Besides this, lateral meristem grows to make the plant body wider. In both the cases, phytohormones play important role in instigating cell division in the growing regions.
2. Blooming of flowers: Flower is the reproductive organ of a plant. It develops from floral bud. Phytohormones play vital role in developing floral buds and blooming of flowers.
3. Caulogenesis and rhizogenesis: Caulogenesis and rhizogenesis mean formation of stem and root respectively. Phytohormones promote development of stem from plumule and root from radical.
4. Germination of seeds: Seeds remain dormant for certain period after its formation. In presence of certain external and internal factors, seeds come out of this dormant state and undergo germination. Phytohormones activate certain enzymes and enhance the supply of food to the embryo to promote the germination process.
5. Tropic movement: Phytohormones play very important role in regulating growth-related movements of curvature, especially phototropic and geotropic movements in plants.

1. Source: Phytohormones are synthesised in the meristematic tissues of apical region of stems and roots, tender leaves, plumule, radical and other growing tissues.
2. Nature of transportation: Phytohormones act close to their sources or away from it. These are carried to different target tissues by intercellular diffusion through xylem and phloem.
3. Function: Phytohormones regulate the growth of apical and lateral buds, blooming of flowers, formation of fruits and seeds, germination of seeds, budding, sensitivity and delay senescence.
4. Fate: Hormones denature after their functions are over. Different hormones are broken down by the action of enzymes or by some other factors. For example, auxin denatures by bright light and indole acetic acid oxidase enzyme. Gibberellin and cytokinin are also disintegrated by gibberellin oxidase and cytokinin oxidase respectively.

1. Apical dominance: By the action of auxin, apical buds grow quickly whereas, the growth of axillary buds is hindered. So, a plant becomes taller by the action of auxin. This is called apical dominance. If the apex of a stem is cut off, the axillary buds start to grow and the plant become bushy due to branching.
   
2. Cell division and cell enlargement: Auxin promotes DNA synthesis and thus, hastens cell division. By this process, number of cells increase in a growing region. Auxin delays hardening of cell walls of young cells. and let them add to size and volume. By the action of auxin, vacuoles grow inside cells, which help to enlarge cells.
3. Growth of fruit: After fertilisation, auxin level elevates inside ovary, which transforms the ovary into a fruit and ovules into seeds. In some flowers, auxin level increases even before fertilisation and the ovary grows to form fruit. Without fertilisation, the ovule cannot develop as seed, therefore, these fruits grow up without any seed inside. Thus, auxin has a role in forming parthenocarpic or seedless fruits.
4. Growth of root: Low concentration of auxin instigates cell division in the growing region of roots. Thus, auxin helps in the growth of root system in plants. Higher concentration of auxin, on the other hand, promotes the growth of adventitious roots from the nodes of stems.
5. Regulation of tropic movement: Auxin plays important role in controlling tropic movement in plants. Phototropic and geotropic movements occur under direct control of auxin due to its unequal distribution.

1. Breaking dormancy of seed and bud: For a certain period, the sign of life is not visible in seeds. This phase is called dormancy of seed. During dormant stage, seed contains less gibberellin. Just before germination, gibberellin level elevates in it. This phytohormone increases activity of enzymes in the seed and help in breaking its dormancy and facilitates germination.
2. Promoting growth of internodes: Gibberellin increases the rate of cell division in the intercalary meristem. Due to this, the internodes of the stem increases in length and thus, the overall height of the plant increases.
3. Increasing the size of the fruit: Gibberellin quickens the growth of fruits and thus, increases their size. Synthetic form of gibberellin also helps in formation of seedless or parthenocarpic fruits: Seedless tomatoes, apples, pears, grapes, etc. can be produced by gibberellin treatment.
4. Increasing the size of leaves and flowers: Gibberellin enhances cell division to increase the size of leaves and flowers.

1. Promoting cell division: The main function of cytokinin is to bring about cytokinesis in plant cells. With the help of auxin, it helps in synthesis of DNA during the S-phase of cell cycle. In this way, cytokinin helps in mitosis. It also plays role in enlargement of newly divided cells.
2. Promoting growth of axillary buds: Cytokinin promotes the development and growth of axillary buds. By this action, many branches develop in a plant and it becomes bushy.
3. Preventing shedding of leaves: Due to degeneration of the tissues of leaf base, a leaf shed off. Cytokinin prevents degeneration of the tissues at the leaf base and thus, prevents early shedding of leaves.
4. Delaying senescence in plants: Cytokinin holds up degeneration of nucleic acids and proteins within cells. It also assists in synthesis of certain proteins. By this process, cytokinin helps to keep the cells alive for longer period, thus delays senescence in plants. The flowers of bouquet or flower vase are sprayed with cytokinin to keep them fresh for longer time.
5. Preventing apical dominance: Cytokinin prevents free growth of apical bud. By this action, it prevents a plant to become markedly tall.

1. Developing new plants from stem cuttings: Cuttings are used for artificial vegetative propagation of different plants like rose, Hibiscus, marigold, Chrysanthemum, etc. After cutting the twigs from a mother plant, solution of synthetic auxin or auxin powder is applied at the cut end. Then, these cuttings are planted in moistened soil. By the action of this hormone, adventitious roots grow from the cut end and the cutting grows as an individual daughter plant.
2. Preventing shedding of immature fruits: Sometimes, immature fruits shed off from the plant. If these plants are sprayed with synthetic auxin solution for a few times during early developmental phase of the fruits, rate of immature shedding declines sharply. Horticulturists spray auxin solution on mango, litchi, grapes, banana and several other fruit plants to prevent immature shedding of fruits. Synthetic gibberellin and synthetic cytokinin are also effective.
3. Destroying weeds: Weeds growing in the crop fields share water and nutrients with the agricultural crops. This affects the quality of production. Scientists have revealed that application of certain phytohormones destroy the dicotyledonous herbs and shrubs. Application of a synthetic auxin named 2, 4-D effectively kills dicotyledonous weeds from monocot crop (paddy, wheat, etc.) fields.
4. Production of parthenocarpic fruits: Fruits, produced from the ovary without fertilisation do not contain seeds and become larger. These are called parthenocarpic fruits. A treatment of auxin solution before maturation of flowers triggers the development of ovary. As a result, seedless fruits are produced before fertilisation. Synthetic auxin is successfully applied on the plants of guava, grapes, banana, watermelon, etc. to produce seedless fruits. Synthetic gibberellin is comparatively more effective on tomato plants. These two synthetic phytohormones are used to produce parthenocarpic fruits.

Short Answer Type Questions

Very Short Answer Type Questions

Multiple Choice Questions & Answers [MCQ]

Answer in a single word or sentence

TOPIC – 3

SUMMARY

• Hormone co-ordinates between different functions in animals. One hormone control the secretion of another hormone called feedback regulation. Increase or decrease secretion of regulator hormone results in increase or decrease of the hormone regulated by it.
• The main endocrine glands or structure secreting hormones are-hypothalamus, pituitary, thyroid, pancreas, adrenal gland, testes and ovary.
• The secretion of pituitary control the secretion of other glands and so it is called the ‘Master gland: Pituitary has two lobes. Hormones of anterior pituitary like ACTH control secretion of adrenal gland, TSH control secretion of thyroid, GH controls the growth and the GTH controls the secretion of gonad and development of the body. The posterior pituitary secretes ADH or vasopressin which regulates the water balance and oxytocin helps in child birth.
• Hormones from hypothalamus like CRH regulates secretion of ACTH, GHRH regulates secretion of GH, TRH controls secretion of TSH and GnRH regulates the release of GTH. Hypothalamus controls pituitary and is thus called ‘Master of master gland’.
• T₃ and T, or thyroxine is released from thyroid gland and control the metabolism. Thyroxine is also known as calorigenic hormone.
• Pancreas is a mixed gland releasing pancreatic juice and hormone. Cells of the islets of Langerhans release insulin and glucagon. Insulin decreases blood sugar whereas glucagon increases it.
• Due to the presense of adrenal gland above the kindney it is also known as suprarenal gland. The medulla of adrenal gland secretes the emergency hormone adrenaline.
• The gonad of male is testes and ovary in female. Testes secrete male sex hormone testosterone and ovary secrete oestrogen.
• The less secretion of hormone cause disease like-low GH or STH cause dwarfism, low insulin cause diabetes melitus, ADH cause diabetes incipidus, low thyroxine cause goiter.

Long Answer Type Questions

1. Source: Animal hormones are secreted from ductless or endocrine glands. Some hormones are released from cluster of secretory cells (present in the inner lining of stomach and intestine, etc.).
2. Chemical nature: Animal hormones are protein, peptide, glycoprotein or steroid in nature.
3. Transportation: Hormones are transported from their source to the respective target organs through blood, lymph or other body fluids.
4. Function and fate: Hormones act upon specific glands or tissues to regulate their secretory, biological and physiological activities. After accomplishing the job, hormones denature at once.
5. Messenger activity: Hormones carry chemical messages from their source to target organs; hence, these are called ‘chemical messenger!
6. Control mechanism: In most of the cases, secretion of endocrine gland is controlled by secretion of other glands which is regulated by the secretion of the endocrine gland itself. This is known as feedback mechanism. Therefore, quantity of secretion of a controlling gland varies with the rate of secretion from the other endocrine glands as well as by its own secretion.

1. Pineal gland: It is situated at the dorsal side of the third cerebral ventricle in diencephalon region of the forebrain.
2. Pituitary gland: Remains attached to the hypothalamus of diencephalon of forebrain with a stalk, called hypophysial stalk or infundibulum. It remains protected in a small cavity of the sphenoid bone of skull, called sella turcica.
3. Thyroid gland: Placed at the ventral side of the junction of larynx and trachea. It has two lobes connected by an isthmus.
   
4. Parathyroid gland: Located at the base of neck. It has four lobes, placed at the dorsal side of the thyroid gland.
5. Pancreas gland: This gland is located transversely just below the stomach.
6. Adrenal gland: This gland is two in number, each placed on the top of a kidney inside the abdominal cavity.
7. Ovary. It is also two in number, placed at two sides of the uterus inside the lower abdominal cavity of a woman.
8. Testis: This is also two in number. Two spermatic cords hold the two testes inside a sac-like structure, called scrotum, outside the lower abdomen of a man.

1. GHRH: It controls the secretion of growth hormone from somatotroph cells of anterior pituitary.
2. GnRH: It controls the release of gonadotropic hormone from gonadotroph cells of anterior pituitary.
3. PRH: It controls the release of prolactin from lactotroph cells of anterior pituitary.
4. TRH: It controls the release of thyroid stimulating hormone from thyrotroph cells of anterior pituitary.
5. CRH: It controls the release of adrenocorticotropic hormone from corticotroph cells of anterior pituitary.

1. FSH or Follicle Stimulating Hormone: [1] This hormone helps in the development of ovarian follicles in ovary and secretion of oestrogen in females. [2] In males, it regulates the spermatogenesis process.
2. LH or Luteinising Hormone: [1] It helps in the ovulation from matured ovarian follicle and formation of corpus luteum. [2] It controls the secretion of progesterone from corpus luteum.
3. ICSH or Interstitial Cell Stimulating Hormone: It stimulates the interstitial cells of Leydig to release testosterone.
4. LTH or Luteotropic Hormone or Prolactin: [1] It stimulates the mammary glands to produce and secrete milk. [2] This hormone keeps the corpus luteum intact during pregnancy and maintains the secretion of progesterone from it.

1. Development of secondary sexual characters: Oestrogen regulates development of breasts, distribution of hair in axilla and pubis-in women. It also regulates the lustre of skin, growth of hair, distribution of fat in breasts, shoulder, hips and thigh, shaping of larynx for soft womanly voice, etc.
2. Growth and development of accessory sex organs: Oestrogen controls the growth and development of uterus, fallopian tubes and vagina. It helps in widening of pelvis.
3. Development of ovary and regulates ovulation: This hormone regulates the growth and development of ovary, maturation of ovum and ovulation process.
4. Regulation of menstrual cycle: Oestrogen with the help of other hormones regulates the normal rotation of menstrual cycle.
5. Bone formation: In females, oestrogen increases calcium uptake by bones from blood. Therefore, after menopause, bone density reduces due to lack of calcium which results due to the deficiency of oestrogen.
6. Controlling metabolism: Oestrogen increases synthesis of fat and protein and deposition of fat below skin in the lower portion of the body to provide the body a feminine shape.

1. Development of uterus: Progesterone and oestrogen jointly help in development of uterus.
2. Implantation: Progesterone helps in the implantation of early embryo in the uterine wall.
3. Embryogenesis: After implantation, progesterone helps in further embryonic development. Hormone also helps on the formation of placenta occurs.
4. Maintaining pregnancy: Progesterone assists in maintaining pregnancy, growth and nutrition of the foetus.
5. Growth of mammary gland: Oestrogen and progesterone jointly help in the growth of mammary glands during pregnancy. In this phase, the follicles of milk glands and tubules develop quickly.
6. Effect on ovary: During pregnancy, excess progesterone is secreted from placenta to reduce the secretion of FSH and LH, so that, ovulation and menstrual cycle stops.
7. Regulation of menstrual cycle: Progesterone along with other hormones regulates the normal functioning of the menstrual cycle.

1. Maturation of testes and spermatogenesis: Testosterone helps in the maturation of testes during adolescence. In sexually matured males, this hormone regulates the male gamete formation or spermatogenesis.
2. Development of accessory male sex organs: Testosterone controls the growth and development of different accessory male sex organs and glands.
3. Development of secondary sexual characters: By the action of this hormone, an adolescent male develops masculine musculature, husky voice, beards and moustache, axillary and pubic hair, etc.
4. Growth of muscles and bones: After adolescence, testosterone helps in the growth of skeletal muscles and bones by quickening protein synthesis in the concerned tissues.
5. Effect on metabolism: Testosterone increases basal metabolic rate in males.

Short Answer Type Questions

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Multiple Choice Questions & Answers [MCQ]

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TOPIC – 4

RESPONSE AND PHYSICAL CO-ORDINATION IN ANIMALS-NERVOUS SYSTEM

SUB-TOPIC 4.1

NEURAL CONTROL AND CO-ORDINATION, NERVOUS PATHWAY, NEURONE, NEUROGLIA AND NERVES, TYPES OF NERVE, GANGLIA, SYNAPSE

SUMMARY

• Animals can respond to environment without chemical secretion. The nervous system allows the organism to interact with its environment, appropriately. Different organs of the body are directly connected to the nervous system. The actions of these organs are controlled by the nervous system. This is known as neural co-ordination.
• We respond in respect to various types of external and internal stimuli through a specific neural pathway. This neural pathway is-stimulus-receptor-nerve centre-effector-response. Like we open the door by the activity of muscle (effector) after hearing (sound receptor) the door bell (stimulus). Here, our brain functions as nerve centre.
• The unit of nervous system is neurone. The three structural parts of neurone are dendron, cell body and axon. It helps in sending and receiving the stimulus.
• There are neuroglia or glial cells which act as matrix of neurones and also help in defence of the nervous system, nutrition of neurones and fast transportation of stimulus.
• The long projection of neurones or axons get covered by different membranes and form the nerve.
• The cell bodies of the neurones of the peripheral nervous system forms a cluster and is covered by connective tissue. This is known as nerve ganglion. It controls the function of oesophagus, digestive glands, etc.
• The junction of two neurone is called the synapse. Nerve impulses are transmitted from one neurone to other by synapse with the help of neurotransmitters (acetylcholine, dopamine, etc).

Long Answer Type Questions

1. What do you understand by the terms neural control and neural co-ordination? Explain how neural control and neural co-ordination are established in case of running.

Ans. Neural control and neural co-ordination

Neural control is the process by which nervous system controls all physiological processes as well as movements in order to maintain an equilibrium between the organism and its environment.

Neural co-ordination is the process by which nervous system co-ordinates various physiological and metabolic functions of an organism with muscle contraction, movements, locomotion, hormone and neurotransmitter release, etc. is called neural co-ordination.

Neural control and neural co-ordination during running

A suitable example where neural control and co-ordination is established is running. During running, an increased demand of energy and oxygen occurs. To meet this increased energy and oxygen demand, both force and frequency of respiration and cardiac output is increased. These events lead to increased mobilisation of oxygen and glucose in the muscle cells, resulting in increased metabolic rate in these cells, which leads to alteration of levels of oxygen and carbon dioxide in blood. This is sensed by the brain which then send signals to the spinal cord and the respiratory muscles (diaphragm, intercostal muscles) thus changing the rate of respiration. In this way, the nervous system co-ordinates with different systems of the body in order to control a definite function.

2. Describe the nervous path with example.

Ans. Nervous path

Nervous system of our body receives external and internal stimuli and makes us respond accordingly. For this co-ordination, body needs a nervous path, which is built in the following way. At first, the ‘sensory organs or receptors receive sensory stimulation from any external or internal stimulus. This stimulus generates a nerve impulse in the receptor cells. Sensory nerve then carries it to the central nervous system. Within the central nervous system, sensory impulse is analysed and is converted into motor impulse. Then a motor nerve carries this motor impulse to specific effector organ. The effector organs like glands, muscles, etc. then respond according to the nature of the command from the central nervous system. Example-When a doorbell rings, the sound stimulates the auditory nerves. Soon this sensory impulse is sent to brain. Now brain sends a motor impulse to limbs. Accordingly, we move to the door and open it by the voluntary action of legs and hands.

3. Briefly describe the two main components of nervous system and mention their functions.

Ans. Main components of nervous system and their functions

The two main components of nervous system are-[1] Neurone and [2] Neuroglia.

1. Neurone: Neurone is the structural and functional unit of the nervous system. Each neurone is composed of a cell body and several projections. The cell body contains a distinct nucleus and other common cell organelles like mitochondria, Golgi bodies, etc. Cytoplasm of neurone especially carries Nissl granules and neurofibrils. Centrosome is present in an inactive state. The projections of neurone are of two types-axon and dendron. Axon is longer, unbranched, may or may not be covered with a specialised myelin layer. It does not contain Nissl granules. Dendron is shorter, branched and contains Nissl granules.
   Function: Neurone helps in the transmission of nerve impulse.
2. Neuroglia: Neuroglial cells are modified connective tissue cells, which form a supporting medium for neurones within the central nervous system. About 90% of the total cellular components of central nervous system are made up of neuroglia. There are different types of neuroglia, such as microglia, oligodendroglia, astrocyte, etc. Neuroglial cells are incapable of transmitting nerve impulse.
   Function: The functions of neuroglia are as follows-[1] Neuroglial cells act as supporting cells of the central nervous system. [2] Certain phagocytic neuroglial cells kill pathogens to protect neurones. [3] Few of these cells take part in preparing the medullary layer over axon.

4. Describe the relation between neurone, nerve fibre and nerve with suitable diagram.

Ans. Relation between neurone, nerve fibre and nerve

The relation between neurone and nerve is as follows-

[1] The structural and functional unit of nervous system is called neurone. An ideal neurone is composed of axon, dendron and a cell body. It receives impulse by dendron and then through axon the impulse is transmited to next neurone or to any effector tissue. On the other hand, a membrane-bound axon is called nerve fibre. The fibrous membrane that covers the axon surface is called endoneurium. Some of these nerve fibres unite to form a thin bundle, which is sheathed by another fibrous membrane, called perineurium. A number of such bundles then come together to form a thick bundle, which is then coated by a blood vessel containing connective tissue layer, epineurium, to form a nerve. [2] The afferent nerves carry nerve impulse from receptors to central nervous system and the efferent nerves carry impulse from central nervous system to the effector organs. These efferent and afferent nerves are composed of sensory and motor neurones respectively. Therefore, it becomes clear that both neurones and nerves are meant for transmitting nerve impulse. Practically, the structural elements of nerves, that is, the neurones carry the nerve impulse. So, it can be concluded that nerves, nerve fibres and neurones are closely related to each other.

5. Describe the structure of a typical neurone.

Similar question, Draw a neat diagram of neurone and label the following parts-(a) Dendron, (b) Node of Ranvier, (c) Myelin sheath, (d) Schwann cell.

Ans. Structure of a typical neurone

A typical neurone has two structural components-[1] Cell body or cyton and [2] Projections.

1. Cell body or cyton: The structural features of cell body of a neurone is as follows-[1] The largest, round or star-shaped portion of the neurone is called cell body. [2] The cell body contains thick protoplasm, called neuroplasm, surrounded by a cell membrane. [3] This cell bears a distinct nucleus within it. [4] Neuroplasm contains different cell organelles like mitochondria, Golgi bodies, etc. Other than these, numerous typical nucle oprotein granules, called Nissl granules are present in neuroplasm. [5] Fine thread-like neurofibrils remain scattered within the neuroplasm. (6] Centrosome is present in inactive state, therefore, neurones cannot undergo mitosis.
2. Projections: The projections of neurone are of two types–] Axon and [2] Dendron. Structural features of these two projections are given below.

   Axon: The structural features of axon is as follows-) The longer and unbranched protoplasmic projection of a neurone is called axon. (2] Axon emerges from a conical portion of the cell body, called axon hillock. [3] The semi-liquid cytoplasm present in axon is called axoplasm, which is externally lined by a cell membrane called axolemma. [4] Axoplasm does not contain Nissl granules. (5] In several neurones, axon has an extra lipid-rich insulating coat outside the axolemma, called myelin sheath. [6] The myelin sheath has a number of periodic gaps, which are called nodes of Ranvier. 7] A few tiny nucleated cells remain associated with myelin sheath, these are known as Schwann cells. [8] The neurones with myelin sheath are called medullated nerve fibres whereas the axons having no myelin sheath are called non-medullated nerve fibres. [9] Axon terminally gives off a few fine branches, this portion is called end brush. End of each branch swells to form a synaptic knob or end button.

   

   Dendron: The structural features of dendron is as follows-[1] The shorter and branched protoplasmic projection of a neurone is known as dendron. Branches of dendron are known as dendrites. [2] The base of each dendrone is wide but it  ets terminally finer and branched. [3] Neuroplasm, neurofibrils and Nissl granules are present in dendron, but it does not have any myelin sheath.

6. Mention classification of neurone on the basis of function. Mention main functions of axon and dendron.

Ans. Classification of. neurone

On the basis of function, neurones are of three types-

1. Sensory neurone: The neurones, which carry sensory impulse from the environment, are called sensory neurones. These neurones transter nerve impulse iromn sense organs and receptors to brain or spinal cord (nerve centres). Therefore, these are also known as afferent neurones.
2. Motor neurone: The neurones, which carry motor impuse from central nervous system (brain or spinal cord) to the effector organs or tissues, are called motor neurones. As these neurone carry impulse from brain or spinal cord (nerve centres) to effector organs, hence these are also known as efferent neurones.
3. Inter-neurone: The nerve cells present in central nervous system, which transfer impulses from sensory neurone to motor neurones are called inter-neurones. These neurones are also known as adjustor or relay neurones.

Functions of axon and dendron

1. Axon: Axon transmits nerve impulse from cell body of a neurone to the next neurone or any effector organ.
2. Dendron: Dendron receives nerve impulse from any sensory cell or another neurone and sends it to the cell body of the neurone.

Short Answer Type Questions

1. Illustrate with the help of a word diagram the nervous pathway of the way you will open the door by hearing the door bell.

Ans. When someone rings the bell at door, we listen to the bell with our ears and open the door. In this case, the receptors present in our ear receive the stimulus and send it to the central nervous system (CNS). CNS processes that stimulus and sends motor signals to our body parts (muscle of hands and legs) and as a result we open the door.

2. What is meant by co-ordination?

Ans. Co-ordination is a process of organised regulation of the activities of different organs and organ systems of a living body to enable them to work together effectively and thereby maintaining a balance between the external and internal environment of the body. In animals both nervous system and hormones and in plants only hormones play the role in co-ordination.

3. Define nervous system.

Ans. The organ system made up of neurones and neuroglia, that helps the body to interact with the changes in environment by receiving and responding to external stimuli as well as maintains physical coordination among all other organs and organ systems of the body, is known as nervous system.

4. What would have happened to the higher organisms if they had no nervous system?

Ans. The body of higher organisms is composed of different organs and organ systems. Nervous system maintains co-ordination among the activities of these components. In absence of nervous system, the total system of functional coordination in the higher organisms would have been disrupted.

5. Mention differences between endocrine system and nervous system.

Or, Distinguish between the functions of hormone and nervous system on the following parameters: Nature of function, Pace of function, Time span of function, Fate.

Ans. Differences between endocrine system and nervous system-

Features	Endocrine System	Nervous System
1. Pace of function	Slow	Very fast
2. Nature of function	Chemical co-ordination	Physical co-ordination
3. Duration of effect	Long term	Short term
4. Fate	Degraded after completing its action	Remain unchanged after completing its action

6. What is nerve?

Ans. A bundle of nerve fibres accompanied by blood vessels and sheathed by three different connective tissue layers is called nerve. It carries nerve impulse to different directions in a body.

7. Name the sheaths of a nerve.

Ans. A nerve remains covered by three different sheaths. Endoneurium is the outermost sheath that covers a bundle of nerve fibres. Perineurium is the second layer that collectively covers few of such bundles. A thicker, blood vessel-carrying outer sheath, called epineurium, covers the entire nerve.

8. What are the functions of nerve?

Ans. The functions of nerve are as follows- [1] Afferent nerves carry nerve impulse from receptor to central nervous system. [2] Efferent nerves carry impulse from central nervous system to the effector organs.

9. Why is neurone called the structural and functional unit of nervous system?

Ans. The structural components of nervous system are brain, spinal cord and nerves. All of these are composed of cellular units known as neurones. Therefore, neurone is treated as the structural unit of nervous system. The main function of nervous system is to transmit nerve impulse. A single neurone also performs the same function. Therefore, it is treated as the functional unit of nervous system.

10. Why the neurones are unable to divide?

Ans. In animal cells, centrosomes play vital role in cell division. The neurones possess inactive centrosomes. That is why the neurones cannot divide.

11. Mention one functional difference between axon and dendron.

Ans. Axon sends nerve impulse from cell body to the next neurone or effector organ or tissue. Dendron, on the other hand, receives nerve impulse from previous neurone or receptor and sends it to the cell body.

12. What is neuroglia?

Ans. Neuroglia or glial cells are the cells of central nervous system that provide support, protection and insulation to the neurones. But they are incapable of transmitting nerve impulses. Dendrocyte, oligodendrocyte and astrocyte are different types of glial cells.

13. Distinguish between neurone and neuroglia.

Ans. Differences between neurone and neuroglia-

Features	Neurone	Neuroglia
1. Transmission of nerve impulse	Capable	Incapable
2. Function	Coordination among different parts of the body by transmission of nerve impulse	Supports and protects the neurones in central nervous system
3. Divisibility	Absent	Present

14. What is nerve ganglion?

Ans. Aggregation of cell bodies of a number of neurones, covered by a sheath of connective tissue, appear as distended regions along a nerve. Such a swollen region is called nerve ganglion.

15. What is nerve impulse?

Ans. Nerve impulse is an electro-chemical signal that travels along a nerve fibre at a fast speed from one neurone to next due to momentary alteration of ionic concentration at two sides of neurilemma.

16. What is synapse?

Ans. Synapse is the junction between two nerve cells or neurones, across which nerve impulses pass from one neurone to the next by diffusion of a neurotransmitter. In this junction, the impulse-sending neurone is called pre-synaptic neurone and the impulse-receiving neurone is called post- synaptic neurone.

17. State the function of synapse.

Ans. Synapse transmits information between neurones or neurones and their target cells. They also act as valves to ensure that impulses pass across them in one direction only.

18. Write a note on neurotransmitters.

Ans. Neurotransmitters are certain biochemical substances, which are secreted within the synaptic cleft from the pre-synaptic neurone to carry nerve impulse from it to the post-synaptic neurone. Some of the most important neurotransmitters are-acetylcholine, adrenaline, dopamine, etc.

19. Mention differences between sensory neurone and motor neurone.

Ans. Differences between sensory neurone and motor neurone-

Features	Sensory neurone	Motor neurone
1. Direction of nerve impulse	From receptor to central nervous system	From central nervous system to effector
2. Length of axon	Comparatively short	Comparatively long
3. Contact of dendron	With the receptor	With central nervous system
4. Contact of axon	With central nervous system	With the effector

20. What are afferent nerves?

Ans. The nerves, which carry sensory impulse from the receptor to the central nervous system, are called afferent nerves. Example-Olfactory nerve, optic nerve, auditory nerve, etc.

21. What are efferent nerves?

Ans. The nerves, which carry motor impulse from central nervous system to the effector organs or tissues, are called efferent nerves. Example- Trochlear nerve, hypoglossal nerve, etc.

22. What are mixed nerves?

Ans. The nerves, which are composed of both sensory and motor neurones and are capable of carrying impulse in both ways, are known as mixed nerves. Example-Vagus nerve, facial nerve, etc.

Features

1. Type of constituent Afferent

neurone

2. Direction of impulse

From receptor to central

nervous system (brain and

spinal cord)

Olfactory, optic, etc.

23. Mention the characters of afferent nerves.

Ans. The characters of afferent nerves are as follows-[1] These nerves are composed of sensory neurones. [2] These nerves carry impulse from receptors to central nervous system.

24. Mention the characters of mixed nerves.

Ans. The characters of mixed nerves are as follows- [1] These nerves are composed of both sensory and motor neurones. [2] Mixed nerves carry sensory impulse from sense organs to central nervous system and motor impulse from central nervous system to the effector organs or tissues.

25. State the characters of efferent nerves.

Ans. The characters of efferent nerves are as follows-[1] Efferent nerves are composed of motor neurones. [2] These nerves carry impulse from central nervous system to the effector organs.

26. What are effectors?

Ans. The organs, glands, muscles or tissues of the body, which respond to motor impulses by performing specific functions, are called effectors. Example-Voluntary muscles, different glands, etc.

27. What is receptor?

Ans. There are certain cells or organs, which can sense any change in internal or external environment and transform this stimulation as nerve impulse. These cells or organs are called receptors.

Very Short Answer Type Questions

Multiple Choice Questions & Answers [MCQ]

1. The portion of a neurone from which the axon emerges, is called-

A. Axis cylinder

B. Axon hillock

C. Dendrite

D. Dendron

Ans. B

2. The portion of a nerve cell that is devoid of Nissl granules is-

A. Dendrite

B. Axon

C. Cell body

D. All of these

Ans. B

3. An effector is-

A. Ear

B. Muscle

C. Skin

D. Nose

Ans. B

4. Physical co-ordinator in animal body is-

A. Hormone

B. Heart

C. Nervous system

D. Circulatory system

Ans. C

5. The membrane that surrounds the axoplasm is called-

A. Axolemma

B. Neurilemma

C. Plasmalemma

D. Pleura

Ans. A

6. Which of the following is a neurotransmitter?

A. Glycogen

B. Glucose

C. Lipid

D. Acetylcholine

Ans. D

7. Which of the following is a motor nerve?

A. Vagus

B. Oculomotor

C. Facial

D. Trigeminal

Ans. B

8. The multicellular organism that does not have nervous system is-

A. Tapeworm

B. Roundworm

C. Starfish

D. Sycon

Ans. D

9. The structural and functional unit of nervous system is-

A. Nephron

B. neurone

C. Axon

D. Neuroglia

Ans. B

10. Which of the following is related to Schwann cell?

A. Dendrite

B. Axon

C. Cell body

D. Synapse

Ans. B

11. Vagus nerve is a type of-

A. Motor nerve

B. Mixed nerve

C. Sensory nerve

D. Spinal nerve

Ans. B

12. The branches of dendron are called-

A. Dendrites

B. End plates

C. Myelin sheath

D. Axon

Ans. A

13. Optic nerve is a type of-

A. Motor nerve

B. Sensory nerve

C. Mixed nerve

D. Efferent nerve

Ans. B

14. Which of the following is a motor nerve?

A. Hypoglossal nerve

B. Auditory nerve

C. Olfactory nerve

D. Optic nerve

Ans. A

15. The cell bodies of neurones unite to form-

A. Neuroglia

B. Nerve ganglion

C. Axon

D. Synapse

Ans. B

16. Nucleus of a neurone is present in-

A. Axon

B. Neurocyton

C. Dendron

D. Axon hillock

Ans. B

17. Any change in internal or external environment that may generate a response in a living organism is called-

A. Receptor

B. Response

C. Sensation

D. Impulse

Ans. D

18. The reaction, shown by an organism by the action of a stimulus is called-

A. Effect

B. Sensation

C. Response

D. Reception

Ans. C

19. The ability of any organism to respond to a stimulus is called-

A. Effector

B. Sensitivity

C. Excitability

D. Receptor

Ans. B

20. The broader portion of a neurone that carries nucleus is called-

A. Cell body

B. Nissl body

C. Axon

D. Dendrite

Ans. A

Answer in a single word or sentence

1. Which is the structural and functional unit of nervous system?

Ans. Neurone

2. What is the name of the conical portion of the cell body of a neurone from where the axon emerges?

Ans. Axon hillock

3. What are the fine and branched ends of an axon called?

Ans. End brush

4. Where is the myelin sheath found?

Ans. Myelin sheath is found on the outer surface of axons of myelinated or medullated neurones.

5. Write one function of myelin sheath.

Ans. The main function of myelin sheath is to facilitate the conduction of electrical impulses through the nerve cells.

6. Name two systems of human body that perform the coordinating function.

Ans. Nervous system and endocrine system

7. Name the main parts of a neurone.

Ans. The main parts of a neurone include- [1] Cell body, [2] Dendron and [3] Axon.

8. Which cytoplasmic material is seen only in neurones?

Ans. Nissl granules

9. Name the point of connection between two successive neurones.

Ans. Synapse

10. Which chemical substance is released from the end brush of neurone?

Ans. Neurotransmitter

11. Name the supporting cells that are present only in central nervous system.

Ans. Neuroglia

12. Which type of stimulus do pressure, heat and light belong to?

Ans. External stimulus

13. Which type of stimulus do hunger, thirst and pain belong to?

Ans. Internal stimulus

14. What is the cell body of a neurone called?

Ans. Neurocyton or perikaryon

15. Name the dense cytoplasm present in the cell body of neurone.

Ans. Neuroplasm

16. Name the fine fibrillar materials present in cytoplasm of nerve cells.

Ans. Neurofibrils

17. What do you mean by neurotrans mitter?

Ans. Neurotransmitters are chemicals that help in the transmission of nerve impulse throughout the nervous system.

18. Name any two motor nerves.

Ans. Trochlear and hypoglossal nerves

19. Name the swollen region of nerves, made up of a cluster of cell bodies of neurones.

Ans. Nerve ganglion

20. What is the main function of nerve fibre?

Ans. The main function of nerve fibre is to transmit nerve impulse.

21. Where the schwann cells are located?

Ans. Schwann cells are located in the axon of the neurones.

Fill in the blanks

1. The long, unbranched projection of neurone is called ……..

Ans. Axon

2. The regions of a medullated neurone, devoid of myelin sheath are called nodes of ……..

Ans. Ranvier

3. The ……… is inactive in neurone, that is why these cells never divide.

Ans. Centrosome

4. The junction of two neurones is known as ………..

Ans. Synapse

5. The ………. of the cell body of a neurone is called neuroplasm.

Ans. Cytoplasm

6. The membrane of synaptic knob is known as ……… membrane.

Ans. Pre-synaptic

7. As nerve impulse reaches the pre-synaptic region, ……….. is secreted from the axon end brush.

Ans. Acetylcholine

8. The parts of living body, which receive stimuli from the environment, are called ……….. 

Ans. Receptor

9. The parts of living body, which respond to stimuli; are called ……… 

Ans. Effector

10. The fine fibrillar structures, named ………… extend from neuroplasm to dendrons and axons.

Ans. Neurofibril

11. The small, fine filamentous protoplasmic projection of cell body are called ………

Ans. Dendron

12. The conical region of the cell body from which the axon emerges is called ……….

Ans. Axon hillock

13. The nerves composed of both sensory and motor neurones is called …….. nerve.

Ans. Mixed

14. The main function of ………. is to carry nerve impulse.

Ans. Neurone

15. Nucleated ………. cells are present in between myelin sheath and neurilemma.

Ans. Schwann

SUB-TOPIC – 4.2

TYPES OF NERVOUS SYSTEM, BRAIN AND SPINAL CORD, REFLEX ACTION AND REFLEX ARC

SUMMARY

• Human nervous system can be divided into three divisions like–central nervous systen, peripheral nervous system and autonomic nervous system. Central nervOUs system is composed of brain and spinal cord. Cranial nerves arising from brain and spinal nerves arising from spinal cord together form the peripheral nervous system. Autonomous nervous system is composed of sympathetic and parasympathetic nervoUs system.
• The main portion of brain is the cerebral cortex of forebrain which controls intelligence, memory, auditory and visual sensations, speech, etc. The thalamus of forebrain recognises pain, touch, pressure, heat. Hypothalamus regulates the feeling of hunger and thirst. It also regulates the body temperature and involved in emotional expression. The midbrain connects the forebrain and hind brain. The pons of hindbrain contracts and expands the heart. Cerebellum of hind brain controls the body balance and body posture. Medulla oblongata controls breathing, sneezing, salivation, engulfing, etc. Spinal cord functions as the central control centre of the reflex action.
• Reflex actions are defined as the automatic response to any kind of stimulus carried out by spinal cord and which is sudden and spontaneous. The nervous or neural pathway through which reflex action takes place is called reflex arc. Sneezing, coughing, blinking of eye, etc. are inborn reflex action. Playing a musical instrument, salivation at the sight of favourite food are examples of conditioned or acquired reflex action. These reflex actions have great importance in daily life.

Long Answer Type Questions

1. Classify human nervous system. Give brief description of each type of nervous system.

Ans. Classification of human nervous system

Human nervous system can be classified into three types. These are-0 Central nervous system (CNS), [2] Peripheral nervous system (PNS) and (3] Autonomic nervous system (ANS).

Description of different nervous systems

A brief description of different nervous systems are given below.

1. Central nervous system: This type of nervous system is composed of brain and spinal cord. It is the main neural control centre of the human body. This system controls all intellectual activities of an individual and regulates the overall coordination of the body with any change in its internal and external environment.
2. Peripheral nervous system: This type of nervous system is composed of 12 pairs of cranial nerves and 31 pairs of spinal nerves. This system coordinates the activities of the body by sensory and motor nerves connected with the central nervous system.
3. Autonomic nervous system: This nervous system is composed of certain cranial and spinal nerves. Functionally, it is of two types-sympathetic nervous system and parasympathetic nervous system. This nervous system controls the functions of all visceral organs, glands and involuntary muscles.

2. Give brief description of central nervous system of human.

Ans. Central nervous system of human

The central nervous system of human is composed of the brain and the spinal cord. A brief description of these two are mentioned below.

1. Brain: Brain of human is divisible into three main parts-forebrain, midbrain and hindbrain.
   

   Forebrain: The structural features of the forebrain is as follows-[1] Forebrain is composed of cerebrum, rhinencephalon, corpus striatum, thalamus and hypothalamus. The first three combines to form telencephalon, and the last two combine to form diencephalon. [2] Cerebrum is the largest part of the brain. It is divisible into two identical hemispheres. These hemispheres are interconnected by a nerve bundle, called corpus callosum. [3] The outer portion of cerebrum is composed of grey matter and the inner portion is made up of white matter. The grey outer portion is called cerebral cortex. [4] Below the cerebrum an oval structure called thalamus is present; which is also made up of grey matter. [5] Hypothalamus is the smallest part of forebrain present below the thalamus. It is composed of both white and grey matter. Midbrain: This portion of human brain is located between forebrain and hindbrain. It is made up of two portions-tectum and cerebral peduncle.

   Hindbrain: This is the posteriormost portion of the human brain. It is composed of two parts- metencephalon and myelencephalon or medulla oblongata. Metencephalon has two parts- cerebellum, pons. Out of these, cerebellum is the largest portion of hindbrain.
2. Spinal cord: The structural features of the spinal cord are as follows-[1] It is a long tubular structure extended from the base of medulla oblongata to the space between the first and second lumbar vertebrae through the neural canal of the vertebral column. [2] A total of 31 pairs of spinal nerves emerge laterally from the spinal cord. It is divisible into five regions-cervical (8 pairs), thoracic (12 pairs), lumber (5 pairs), sacral (5 pairs) and coccygeal (1 pair). [3] The central canal of the spinal cord is filled with cerebrospinal fluid. [4] Length of spinal cord in healthy human adult male is about 45 cm and that of healthy adult female is about 42 cm. [5] The lower end of the spinal cord is tapering from which several fibrils grow.

3. Mention the location and functions of the following-[1] Midbrain, [2] Medulla oblongata. 

Ans. Midbrain or mesencephalon

The location and functions of midbrain-

1. Location: Midbrain is located as a connective in between forebrain and hindbrain. It is a small area composed by tectum and cerebral peduncle.
2. Functions: The functions of midbrain are as follows-[1] Midbrain coordinates the function of forebrain and hindbrain. [2] Tectum portion of midbrain acts as the reflex centre for vision and hearing. [3] Midbrain plays important role to control body temperature. [4] It also helps to regulate muscle tension. [5] It coordinates the movement of voluntary muscles.

Medulla oblongata

The location and functions of medulla oblongata-

1. Location: Medulla oblongata is located below the pons and just above the spinal cord.
2. Functions: The functions of medulla oblongata are as follows-[1] Medulla oblongata regulates breathing, contraction and relaxation of heart, blood pressure, etc. [2] Controls salivation and vomiting. [3] Ninth to twelfth cranial nerves originate from this region.

4. What is reflex path? Name five components of a reflex path and mention their functions.

Ans. Reflex path

The neural path, through which nerve impulse rotates to accomplish a reflex action, is known as reflex path or reflex arc.

Components of reflex path

Reflex path has five components, which are mentioned below.

1. Receptor: The receptor generates a sensory nerve impulse in response of a stimulus.
2. Afferent neurone: This neurone carries sensory impulse from receptor to the nerve centre.
3. Nerve centre: It is located in the grey matter of the spinal cord. Here, sensory impulse is converted into motor impulse and it is transferred from sensory neurone to motor neurone through inter-neurone.
4. Efferent neurone: It carries motor impulse from the nerve centre to the effector organ.
5. Effector: Muscles or glands are the effector organs, which show specific response to specific stimulus.

5. Briefly describe the functional activities of a simple reflex path or reflex arc with a common example.

Similar question, Draw a diagram of a reflex arc and label the following parts: (a) Receptor, (b) Sensory nerve, (c) Nerve centre, (d) Motor nerve.

Ans. Functional activities of a simple reflex arc

If a thorn pricks our sole, we withdraw the foot at once. This is the example of a reflex action. The process of this reflex action occurs in the following way-[1] As the thorn pricks, the receptors in the skin below our sole sense the stimulus. [2] The receptors at once, generate a sensory impulse and sensory or afferent neurone (afferent nerve) carries it to the spinal cord (nerve centre). [3] Immediately, the sensory impulse is modified into motor impulse and it is conveyed to the motor or efferent neurone (efferent nerve) by an inter-neurone within the spinal cord. [4] The efferent neurone instantly carries the motor impulse to the leg muscles (effector). [5] The muscles of the leg act at once to lift the foot promptly to avert a deeper prick.

Short Answer Type Questions

1. What is central nervous system?

Ans.The main controlling part of nervous system, which is composed of brain and spinal cord, is known as the central nervous system.

2. What is peripheral nervous system?

Ans. The type of nervous system, which is composed of different cranial and spinal nerves, is known as peripheral nervous system.

3. What is autonomic nervous system?

Ans.The type of nervous system, which is composed of certain cranial and spinal nerves, which control the involuntary activities of different visceral organs, is known as autonomic nervous system. Visceral activities such as breathing, heart beat, digestive processes, etc. are controlled by the autonomic nervous system.

4. Write the parts of central nervous system and peripheral nervous system. 

Ans.Central nervous system consists of brain and spinal cord and peripheral nervous system consists of sympathetic and parasympathetic nervous system.

5. What are the components of peripheral nervous system?

Ans.The nerves emerging directly from the central nervous system constitute the peripheral nervous system. The components of this nervous system includes 12 pairs of cranial nerves and 31 pairs of spinal nerves.

6. What is meant by sympathetic nervous system?

Ans.The part of autonomic nervous system that is composed of thoracic and lumbar nerves to control the functions of different visceral organs during emergency conditions (fight or flight response), is called sympathetic nervous system.

7. What is meant by parasympathetic nervous system?

Ans.The part of autonomic nervous system that is composed of cranial and sacral nerves to control functions of different visceral organs during the state of rest or relaxation (rest and digest response), is called parasympathetic nervous system.

8. What is brain?

Ans. Brain is the largest and distended portion of central nervous system, located at the anterior region of spinal cord and remains protected within skull. It controls all neural and intellectual activities and physiological functions in vertebrates.

9. What is cerebral cortex?

Ans.Cerebral cortex is the thick and grey outer layer of the cerebrum, composed of cell bodies of neurones and acts as the controlling centre of memory, intelligence, thinking and all sensory activities.

10. What is thalamus?

Ans. Thalamus is a grey-coloured, paired oval structure, situated below the cerebral hemis-pheres at two sides of the third ventricle and just above the midbrain. It acts as the relay-centre or gatekeeper of the brain. It also senses pressure, pain, heat, etc.

11. What is hypothalamus?

Ans.Hypothalamus is the small portion of the forebrain located just below the thalamus and the third ventricle and acts as the controlling centre of temperature, hunger, thirst, emotions, etc.

12. What is midbrain?

Ans.Midbrain or mesencephalon is the smallest part of brain that connects the fore and hindbrain. This segment of human brain is composed of two parts-tectum and cerebral peduncle.

13. What is pons?

Ans.Pons is the part of hindbrain, located below the midbrain at the ventral side of the fourth ventricle and above the medulla oblongata. It acts as a bridge between midbrain and medulla oblongata.

14. What is medulla oblongata?

Ans.Medulla oblongata is the posteriormost portion of brain, located below the pons and at the apex of the spinal cord. It acts as a control centre for sneezing, coughing, salivation, engulfing, vomiting, etc.

15. What is cerebellum?

Ans. Cerebellum is the largest part of hindbrain, located at the dorsal side of the fourth ventricle that plays the major role in controlling the body balance and coordinated muscular activities.

16. Mention two functions of cerebral cortex.

Ans.Two functions of cerebral cortex are follows-[1] It acts as the controlling centre of memory, intelligence, analysing capacity, power of thinking, etc. [2] It also helps to control the sense of vision, smell, taste, heat, cold, touch, pain, etc.

17. Mention two functions of thalamus.

Ans. Two functions of thalamus are as follows- [1] It acts as the relay station for impulses travelling to and from cerebrum, midbrain, cerebellum, spinal cord. [2] It sends different sensory impulses to the concerned reception centres of cerebral cortex.

18. Mention two functions of hypothalamus.

Ans.Two functions of hypothalamus are as follows-[1] It controls hunger, thirst, sleep, mental stress, body temperature, consciousness, etc. [2] It also controls the secretion of different hormones from the pituitary gland.

19. Mention two functions of midbrain.

Ans.Two functions of midbrain are as follows- [1] It helps to co-ordinate the functions of forebrain and hindbrain. [2] It also controls muscle contraction and maintains equilibrium of the body.

20. Mention two functions of pons.

Ans.Two functions of pons are as follows-[1] It controls facial expression, urination, breathing, movement of jaw and eyeballs. [2] It also maintains functional coordination between cerebrum and cerebellum.

21. Mention two functions of cerebellum.

Ans.Two functions of cerebellum are as follows- [1] It maintains body balance and posture. [2] It regulates voluntary movement of body parts.

22. What is corpus callosum?

Ans.There is a thick bundle of nerves that transversely connects the two hemispheres of the brain. This bundle of nerves of cerebrum, is known as corpus callosum.

23. What is spinal cord?

Ans.Spinal cord is the continuation of medulla oblongata. It is a tubular, neural structure that extends through the neural canal of the vertebral column from the base of medulla oblongata to first or second lumbar vertebra and acts as the controlling centre for reflex action.

24. Mention any two functions of spinal cord.

Ans.Two functions of spinal cord are as follows- [1] Spinal cord acts as the controlling centre for reflex action. [2] It conducts sensory and motor information between peripheral nervous system and central nervous system.

25. Mention the location of meninges. State its function.

Ans. Location: Meninges is located just outside the brain and spinal cord as a membranous outer covering.

Functions: The functions of meninges are as follows-[1] Meninges protects the central nervous system from injury and infection. [2] Capillaries of meninges supply blood to skull and cerebral cortex.

26. What is CSF?

Ans. A transparent and slightly alkaline fluid is present in the ventricles of brain, central canal of spinal cord, sub-dural and sub-arachnoid space of meninges. This is called CSF or cerebrospinal fluid.

27. Mention the location of CSF.

Ans. CSF or cerebrospinal fluid is present in the four ventricles of brain, central canal of spinal cord, sub-dural and sub-arachnoid space of meninges.

28. Mention the functions of CSF.

Ans. The functions of CSF or cerebrospinal fluid are as follows-[1] CSF supplies nutrients and oxygen to the neural cells of central nervous system. [2] It also acts as a cushion to protect the brain and spinal cord against external shocks and pressure.

29. What is reflex action?

Ans. The spontaneous, instantaneous and involuntary response to any external or internal stimulus is known as reflex action. It is under the control of spinal cord.

30. What is meant by innate reflex actions?

Ans. The reflexes, which are inborn, not regulated consciously and are not conditioned through any regular activities, are called innate reflex actions. Example-The suckling urge of a newborn baby, blinking of eye.

31. What is meant by acquired reflex actions?

Ans. Certain reflexes, can be acquired by continuous practice or from experience. These are called acquired reflex action. Example- Cycling, swimming, etc.

Very Short Answer Type Ouestions

Multiple Choice Questions & Answers [MCQ]

1. The part of human brain associated with controlling body temperature is-

A. Thalamus

B. Cerebellum

C. Hypothalamus

D. Medulla oblongata

Ans. C

2. Which one of the following is the correct reflex.arc?

A. Receptor→ Effector-→ Efferent nerve→ Nerve centre→ Afferent nerve

B. Nerve centre→ Receptor→ Afferent nerve→Effector→ Efferent nerve

C. Efferent nerve→ Receptor→ Afferent nerve →Nerve centre> Effector

D. Receptor→Afferent nerve→ Nerve centre → Efferent nerve→ Effector

Ans. D

3. Determine the number of cranial nerves in human body-

A. 10 pairs

B. 31 pairs

C. 12 pairs

D. 21 pairs

Ans. C

4. Select the correct pair–

A. Cerebrum-Maintenance of balance of the body

B. HypothalamusControl of intelligence and emotion

C. Cerebellum–Control of body temperature

D. Medulla oblongata-Control of heart beat and swallowing of food

Ans. D

5. An example of conditioned reflex is-

A. Approaching of goldfish towards the front wall of the aquarium (for collecting food) by viewing any man in front

B. Quick withdrawal of hand on touching any hot object

C. Suckling of milk by a baby

D. Watering of eye while chopping onion

Ans. A

6. Cycling is a type of-

A. Innate reflex

B. Inborn reflex

C. Brain activity

D. Acquired reflex

Ans. D

7. Cerebrum is the part of-

A. Fore brain

B. Mid brain

C. Hind brain

D. Spinal cord

Ans. A

8. Number of spinal nerves in man is-

A. 10 pairs

B. 12 pairs

C. 31 pairs

D. 33 pairs

Ans. C

9. Relay centre of nervous system is-

A. Thalamus

B. Hypothalamus

C. Cerebrum

D. Cerebellum

Ans. A

10. The length of human spinal cord is about-

A. 45 cm

B. 4.5 cm

C. 45 m

D. 4.5 m

Ans. A

11. Which of the following is the controlling organ of reflex action?

A. Brain

B. Nerve ganglion

C. Neuroglia

D. Spinal cord

Ans. D

12. The portion of central nervous system that holds CSF is-

A. Ventricles of brain

B. Central canal of the spinal cord

C. Both A and B

D. Neurone

Ans. C

13. The outermost covering of central nervous system is called-

A. Pleura

B. Pericardium

C. Peritoneum

D. Meninges

Ans. D

14. Which of the following is not a part of meninges?

A. Dura mater

B. Grey matter

C. Arachnoid mater

D. Pia mater

Ans. B

15. Which of the following is not a part of hindbrain?

A. Pons

B. Cerebellum

C. Tectum

D. Medulla oblongata

Ans. C

16. Corpus callosum is present in-

A. Cerebrum

B. Medulla oblongata

C. Cerebellum

D. Midbrain

Ans. A

17. The mass of the spinal cord of a healthy adult man is about-

A. 15 gram

B. 35 gram

C. 75 gram

D. 95 gram

Ans. B

18. The smallest part of brain is-

A. Cerebrum

B. Cerebellum

C. Optic lobe

D. Mid brain

Ans. D

19. The quantity of cerebrospinal fluid present in a healthy adult human being is-

A. 100 ml

B. 150 ml

C. 200 ml

D. 250 ml

Ans. B

20. Number of ventricles in human brain is-

A. 2

B. 3

C. 4

D. 5

Ans. C

21. Mass of adult human cerebellum is about-

A. 150 gm

B. 250 gm

C. 350 gm

D. 450 gm

Ans. A

Answer in a single word or sentence

1. Which portions of the human brain contain white matter and grey matter?

Ans. The outer portion of human brain contains white matter and the inner portion is composed of grey matter.

2. What are gyrus and sulcus?

Ans. Cerebral cortex of human brain has many folds and grooves. Each outward fold is called gyrus (plural-gyri) and each inward groove is called sulcus (plural-sulci).

3. Which fluid is present inside ventricles of brain and central canal of the spinal cord?

Ans. Cerebrospinal fluid

4. Name the three-layered outer covering of brain.

Ans. Meninges

5. Who was the first to suggest the concept of reflex action?

Ans. Ivan Pavlov

6. What is the full form of CNS?

Ans. Central Nervous System

7. What is the full form of PNS?

Ans. Peripheral Nervous System

8. What the full form of ANS?

Ans. Autonomic Nervous System

9. Which is the largest part of the human brain?

Ans. Cerebrum

10. State the location of white matter and grey matter in the spinal cord.

Ans. In spinal cord, grey matter is present inside and white matter remains surrounding it.

11. Name the protective layer surrounding the central nervous system.

Ans. Meninges

12. Which type of nervous system controls the activities of all visceral organs?

Ans. Autonomic nervous system

13. Which part of nervous system controls the reflex action?

Ans. Spinal cord

14. Which type of nervous system is constituted of the nerves coming out of brain and spinal cord?

Ans. Peripheral nervous system

15. Name the space between dura mater and arachnoid mater.

Ans. Sub-dural space

16. Name the space between arachnoid mater and pia mater.

Ans. Sub-arachnoid space

17. Name the two main parts of human brain.

Ans. Telencephalon and diencephalon

18. What is cerebral peduncle?

Ans. The portion of human brain that connects thalamus with different parts of hindbrain and midbrain is called cerebral peduncle.

19. Which is the longest nerve of human body?

Ans. Sciatic nerve

20. Which is the smallest cranial nerve?

Ans. Trochlear nerve

21. Which part of human brain is concerned with temperature regulation of the body?

Ans. Hypothalamus

22. Which are the main portions of human brain?

Ans. Forebrain, midbrain and hindbrain

23. Which are the main two parts of midbrain?

Ans. Cerebral peduncle and tectum

24. Which are the two main portions of hindbrain?

Ans. Metencephalon and myelencephalon

25. Which type of reflex is the suckling of milk by a baby?

Ans. Inborn or innate reflex

26. What is vermis?

Ans. The fibrous connector of the two cerebellar hemispheres is called vermis.

27. Name the three main parts of hindbrain.

Ans. Cerebellum, pons and medulla

28. Which part of hindbrain regulates sneezing, coughing and vomiting?

Ans. Medulla oblongata

29. Site an example of reflex action in daily life.

Ans. One example of reflex action in daily life is- eyelids close at once, when sudden bright light or any object, like dust particles enter the eye.

Fill in the blanks

1. There are ……….. pairs of cranial nerves in human body.

Ans. 12

2. The complete path of reflex action is called ………

Ans. Reflex arc

3. Brain of vertebrates remains protected inside the ……….

Ans. Skull

4. The reflexes achieved by birth are called ……… reflex.

Ans. Innate

5. Peripheral nervous system is composed of all the ……… emerging from central nervous system.

Ans. Nerves

6. The folds of cerebrum are called ……….

Ans. Gyri

7. The momentary involuntary actions in response to sensory stimulus, controlled by spinal cord is called ….. action.

Ans. Reflex

8. The outer region of cerebrum is called ……….

Ans. Cerebral cortex

9. The higher mental activities are controlled by the ……….. of human brain.

Ans. Cerebrum

10. The largest part of brain is ……….

Ans. Cerebrum

11. ……… region of brain control body balance.

Ans. Cerebellum

12. The two hemispheres of cerebellum are connected by ……….

Ans. Vermis

SUB-TOPIC – 4.3

EYE AS A SENSE ORGAN IN HUMAN, ACCOMMODATION, DEFECTS OF VISION AND CORRECTIVE MEASURES

SUMMARY

• Eye is a human sense organ which acts as light receptor organ and helps in vision. The structural components of eye are-eyeball, protective structures and eye muscles.
• Eyeball is composed of three layers. The outer fibrous layers is composed of sclera and cornea. Middle layer is composed of the choroid containing blood capillaries, ciliary bodies, and iris. The innermost neural layer is the retina. It is composed of rod and cone cells.
• Inside the eye there is a biconvex lens behind the iris. The eyeball has three chambers. The front chamber is located between cornea and iris; middle chamber is located between iris and lens contains aqueous humour. The posterior vitreous chamber, located between lens and retina contains vitreous humour. The protective parts of eye are conjunctiva, eyelid and lacrimal glands. The eyeball is connected by eye muscle inside the eye socket.
• Monocular vision is a type of vision in which one eye of the animal moves and sees objects independently of the other eye. Most preys have this type of vision. On the other hand, binocular vision is a type of vision where both eyes of an animal are used at the same time. Most predatory animals including human employ this type of vision.
• The elasticity of ciliary muscle and lens helps the eye to produce right image from different distance perfectly. This is called accommodation. Ciliary muscles change the curvature of the lens, which helps the lens to change its focal length and keep objects in focus.
• There are some important disorders related to eyes. These are myopia (short sightedness), hyperopia or hypermetropia (long sightedness), presbyopia. Accumulation of pigment due to breakdown of protein in lens causes loss of clear vision. It is called cataract.

Long Answer Type Questions

1. Describe the structure of the human eyeball and mention its function.

Or, Describe the structure and function of human eyeball.

Similar question, Draw a neat diagram of the vertical section of the eyeball of human eye and label the following parts-[1] Cornea, [2] Lens, [3] Vitreous humour, [4] Retina. 

Ans. Human eyeball

It is a spherical, fluid-filled portion of the eye. It has two types of structural components-

1. The eye coats: The structure and function of each component of the eye coats are as follows- [1] Eye has three coats-fibrous outer coat, vascularised medial coat and neural inner coat. [2] The fibrous outer coat has two portions, its posterior 5/6th opaque portion is called sclera and the anterior 1/6th transparent portion is known as cornea. The sclera is rigid that keeps the shape of the eye intact. Cornea is a refractive medium that acts as a front window of the eye. [3] The vascularised medial coat is known as choroid. It is black in colour due to the accumulation of melanin pigment. Cornea is rich in blood capillaries. [4] The anterior extension of choroid forms ciliary body and iris. Ciliary body is a muscular extension of choroid that holds the lens in position. It remains attached with suspensory ligament. The pigmented muscular extension of choroid that is present behind cornea is called iris. It has a round aperture at the centre to allow light to enter into the eye. This aperture is known as pupil. Contraction and expansion of iris muscles change the diameter of the pupil to regulate the exposure on the retina. [5] The neural inner coat known as retina is composed of two types of photosensitive cells-rod cells and cone cells. The rod cells are sensitive to dim light and the cone cells senses bright light. [6] Just opposite to the pupil, retina has a tiny depressed spot, called macula lutea of yellow spot. This spot contains cone cells only and is capable of creating the sharpest image in bright light. The region of retina from which the optic nerve emerges is devoid of any photosensitive cells. Therefore, this spot is incapable of sensing light, hence it is called the blind spot.
   
2. Refractive medium: The structure and function of each component of the refractive medium is as follows-[1] The refractive media of eye are-cornea, aqueous humour, lens and vitreous humour. [2] Cornea is a transparent convex layer, present in front the eye as a window glass. [3] The thin anterior chamber of eye between cornea and the lens is filed with a watery fluid called aqueous humour. [4] Behind the iris, a transparent circular biconvex lens is present, that is held in position by suspensory ligaments and ciliary muscles. The lens creates the image on the retina. [5] The posterior chamber of the eyeball behind the lens is filled with a viscous matrix, called vitreous humour. Both aqueous and vitreous humour maintains the pressure inside the eyeball and supply nutrition to different parts of the eye.

2. Mention two importances of accommodation in daily life. How does the eye accommodate to see a distant and a nearer object?

Ans. Importance of accommodation

Two importances of accommodation in our daily life is mentioned below.

[1] While driving a car, the driver has to follow close objects like pedestrians and change over to a distant object like traffic signals instantly. [2] While in the classroom, we look at the blackboard and the very next moment read or write something from the book or on the paper over the desk.

Mechanism of accommodation to view distant and nearer objects

Accommodation enables eye to see any object from both close and long distance. The mechanism is mentioned below.

1. Seeing a distant object: To see a distant object, some sequential adjustments occur inside the eyeball. These are mentioned here.
   Ciliary muscles relaxed → Curvature of lens decreases → Lens becomes thin → Focal length of the lens increases → The image is formed on the retina.
   
2. Seeing a nearer object: To see a nearer object, following sequential adjustments occur inside eyeball.
   Ciliary muscles contract  → Curvature of the lens increases → Lens becomes thick → Focal length of the lens reduces → The image is formed on the retina.

3. Give a brief idea on hypermetropia.

Similar question, ‘A person can see distant objects distinctly but is unable to visualise near object in a perfect way’-Predict what would be the probable cause and suggest the corrective measure for such problem. [Madhyamik ’20] Write a note on cataract.

Ans. Hypermetropia

Hypermetropia is a visual impairment in which a person can see any distant object but unable to find the nearer objects clearly.

1. Characteristic feature: In this disease, the diameter of the eyeball becomes antero-posteriorly compressed or the cornea becomes too much flattened. As a result, the image is formed beyond the retinal surface. So the patient finds a blurred image of the nearer objects.
2. Remedy: To rectify hypermetropia, ophthalmologists recommend (+ve power) convex glass lens. This glass lens creates image on retinal surface and makes the vision clear.

Cataract

Usually due to ageing, deficiency of certain proteins in the eye lens makes it opaque. This condition is called cataract.

1. Characteristic feature: Opacity of the lens increases gradually to make the vision blurred.
2. Remedy: To solve the problem of cataract, an eye surgeon can replace the defective lens with a synthetic plastic lens by surgical procedure.

4. Write a brief note on myopia. What do you know about presbyopia?

Ans. Myopia

Myopia is a visual impairment, in which a person can see nearer objects clearly but unable to see the distant objects.

1. Characteristic feature: In this disease, the diameter of the eyeball becomes antero-posteriorly enlarged or the cornea is too much curved. As a result, the eyeball becomes elliptical and the image is formed ahead of the retinal surface. Therefore, the patient views a blurred image of the distant object.
2. Remedy: To rectify myopia, ophthalmologists recommend (-ve power) concave glass lens. This glass lens creates image on retinal surface and makes the vision clear.

Presbyopia

After attaining the age of 40, most people lose the elasticity of lens. In this situation, the accommo-dation capacity reduces significantly. The visual impairment caused is known as presbyopia.

1. Characteristic feature: A patient suffering from presbyopia cannot see nearer objects clearly. They face problem in reading, writing and dealing with finer tools.
2. Remedy: Presbyopia can be rectified by using bifocal lens.

Short Answer Type Questions

1. What are sense organs?

Ans.The special receptor organs present in animal body, which are capable of sensing only specific type of stimulus and transmit the impulses to the central nervous system, are known as sense organs. There are five sense organs, viz.-ear, skin, eye, nose and tongue.

2. Briefly describe the sclera of eye. Mention its function.

Ans.Sclera of eye: Sclera is the opaque fibrous coat, covering about 5/6th portion of the eye from its posterior side. It is white in colour, rigid and composed of collagen fibres.

Function: Sclera provides shape to the eye and protects it from external injuries.

3. What is choroid? Mention its function.

Ans. Choroid: The melanin-rich, dark coloured layer of eye, that is present in between retina and sclera is called choroid.

Function: Choroid supplies nutrition different parts of the eye. It is black, therefore, prevents reflection inside eyeball and absorbs undesired rays.

4. Where is the retina located? Mention its function.

Ans.Location: Retina is located on the inner back wall of the eye.

Function: Retina receives the visual stimulation by its photosensory cells and sends the visual impulse to brain.

5. Briefly describe the lens of human eye. Mention its function.

Similar question, Mention one function of lens of human eye.

Ans. Lens of human eye: It is a transparent, biconvex, elastic structure located behind the iris. It remains suspended steadily by suspensory ligaments behind the pupil of eye.

Function: Lens creates image on retina by refraction of incident rays of light entering into the eye.

6. Briefly describe the cornea. Mention its function.

Ans. Cornea: Cornea is the 1/6th portion of fibrous protective layer of eye. It is a convex, transparent refractive layer present in front of the eye.

Function: Cornea acts as a refractive medium to allow light to enter into the eye. It operates as a condenser of incident light.

7. What is yellow spot? Mention its function.

Ans. Yellow spot: The spot on retina just opposite to the pupil is highly rich in cone cells. This spot is capable of receiving the brightest and most prominent image of any object. This region is known as macula densa or yellow spot.

Function: Yellow spot is the portion of eye that is specialised for seeing things with maximum clarity.

8. What is fovea centralis?

Ans.The centre of yellow spot on human retina has a tiny depression that contains only cone cells. This region of retina is called fovea centralis.

9. What is blind spot?

Ans.The spot on retina, from which the optic nerve emerges and has no photosensitive cells. Therefore, this spot does not receive any stimulus from light. This spot on retina is known as blind spot.

10. What is aqueous humour? Mention its function.

Ans. Aqueous humour: Aqueous humour is the transparent watery medium that is present in the anterior chamber of eye in between the cornea and the lens.

Function: Aqueous humour is a refractive medium of eye that maintains internal pressure of the anterior chamber and provides nutrition to different parts of it.

11. What is vitreous humour? Mention its function.

Ans.Vitreous humour: Vitreous humour is the transparent viscous medium that is present in the posterior chamber of eye in behind the lens.

Function: Vitreous humour is a refractive medium of eye that maintains internal pressure of the posterior chamber and maintains the perfect shape of the eye.

12. Write the names of the different refractive mediums of eyeball in proper sequence.

Ans.The refractive mediums of eyeball from outside to inside are-cornea-aqueous humour-lens-vitreous humour.

13. What are eye muscles?

Ans. The five strips of muscles, which bind the eyeball to the inner wall of the orbit or eye socket of the skull, are called eye muscles. The eye muscles control both voluntary and involuntary eye movements.

14. State the location of tear gland. Mention its function.

Ans. Location: Tear gland is located below the upper eyelid of each eye.

Function: Tear gland releases a watery secretion to keep the exposed surface of eye wet and clean it from dirt. It contains an enzyme (called lysozyme) that protects the eye against external germs.

15. What will happen if the tear glands stop secreting?

Ans.If tear glands stop secreting, the surface of eye will become dry and coarse. Dirt will settle on eye and will damage the eye surface. Lack of the enzyme lysozyme, will make the eye vulnerable to bacterial attack.

16. What is monocular vision? Name few animals with monocular vision.

Ans.Monocular vision: In certain animals, two different images of two different objects are formed in two different eyes. As a result, the animal spots two different objects by its two eyes at a time. This is called monocular vision.

Animals with monocular vision: Frogs, horses, most birds, fishes, etc.

17. What is binocular vision? Name few animals with binocular vision.

Ans.Binocular vision: In certain animals, same image of a single object is formed in both the eyes at a time. As a result, the animal spots the complete image of the same object by both of its eyes. This is called binocular vision.

Animals with binocular vision: Few animals with binocular vision are man, tiger, owl, etc.

18. What is accommodation of eye?

Ans.Accommodation is the unique ability of eye to focus objects from different distances perfectly and instantly on the retinal surface. This is done by a quick change in curvature of the lens with the help of ciliary muscles and suspensory ligaments.

19. How does eye accommodate to see a nearer object?

Ans.To accommodate the eye to see a nearer, object the ciliary muscles contract and suspensory ligaments relax to increase the curvature of the lens. As a result, the lens becomes thicker and its focal length reduces to create a clear image on the retinal surface.

20. How does eye accommodate to see a distant object?

Ans.To accommodate the eye to see an object located at a distance, the ciliary muscles, relax and suspensory ligaments contract to decrease the curvature of the lens. As a result, the lens becomes thinner and its focal length reduces to create clear image on retinal surface.

21. Mention the names of few visual problems. 

Ans.The names of few visual problems are-myopia, hypermetropia, cataract, presbyopia, astigmatism, etc.

22. What is myopia? Mention the cause of myopia.

Ans. Myopia: The visual impairment in which a person can see the closer objects, but unable to visualise the distant objects clearly, is called myopia.

Cause: In case of myopia, either the shape of the eyeball is too long or the cornea is too much curved. So, the light coming from any distant source creates the image a little ahead of retinal surface to make the distant vision blurred.

23. What is hypermetropia? Mention its cause?

Ans.Hypermetropia: The visual impairment in which a person can visualise the distant objects but unable to see the closer objects clearly, is called hypermetropia.

Cause: In case of hypermetropia either the shape of the eyeball is too short or cornea is too flat. As a result, the light coming from closer source creates the image a little behind retinal surface to make the near vision blurred.

24. What is presbyopia?

Ans.The natural ability of accommodation of human eye decreases gradually after the age of 40 to 45 due to hardening or loss of elasticity of the lens, causing long-sightedness. In this ageing- related visual impairment, individuals face a problem in reading and writing. This disease is called presbyopia.

25. What is cataract?

Ans.Sometimes the lens of human eye becomes opaque. Due to this condition, individuals lose clear vision. This visual impairment is called cataract and if not treated in time, it may cause complete loss of vision.

26. For correction of which defects in vision of eye, spectacles of convex and concave lenses are used?

Ans. Spectacles of convex lenses are used in hyperopia and spectacles of concave lenses are used in myopia.

Very Short Answer Type Questions

Multiple Choice Questions & Answers [MCQ]

1. Which one of the following is a retinal cell?

A. Rod cell

B. Hepatocyte

C. Schwann cell

D. Mast cell

Ans. A

2. Rhodopsin is present in-

A. Cone cell

B. Rod cell

C. Cell body

D. Carrier cell

Ans. B

3. The aperture through which light enters into the eyeball is called-

A. Pupil

B. Cornea

C. Choroid

D. Cochlea

Ans. A

4. The transparent outer covering of eyeball is called-

A. Cornea

B. Sclera

C. Choroid

D. Retina

Ans. A

5. The innermost layer and the most delicate layer of the eyeball where the photoreceptors are located are-

A. Choroid

B. Sclera

C. Retina

D. Cornea

Ans. C

6. Which one among the following helps in low light vision?

A. Cone cell

B. Rod cell

C. Carrier cell

D. Transporter cell

Ans. B

7. The lens used for distant vision is-

A. Thick lens

B. Thin lens

C. Lens of identical curvature

D. All of these

Ans. B

8. The shape of human eye lens is-

A. Concave

B. Convex

C. Bi-convex

D. Bi-concave

Ans. C

9. The spot of retina without rod and cone cells is called-

A. Black spot

B. Yellow spot

C. Fovea

D. Blind spot

Ans. D

10. An enzyme present in tears is-

A. Amylase

B. Maltase

C. Lysozyme

D. Sucrase

Ans. C

11. Near-sightedness is called-

A. Presbyopia

B. Hypermetropia

C. Myopia

D. Cataract

Ans. C

12. The vision problem in which image is formed behind retina is called-

A. Myopia

B. Hyperopia

C. Presbyopia

D. Cataract

Ans. B

13. Which of the following is not a refractory medium of eye?

A. Lens

B. Cornea

C. Sclera

D. Aqueous humour

Ans. C

14. Which of the following gives different colour to the eye?

A. Cornea

B. Iris

C. Lens

D. Choroid

Ans. B

15. The area of eye with most excellent vision is-

A. Lens

B. Cornea

C. Fovea centralis

D. Optic disk

Ans. C

16. The meeting point of retina and optic nerve is called-

A. Yellow spot

B. Choroid

C. Eyespot

D. Blind spot

Ans. D

17. Which nerve receives the visual stimulus?

A. Olfactory

B. Optic

C. Auditory

D. None of the above

Ans. B

18. The liquid present in the chamber between cornea and lens is-

A. Perilymph

B. Endolymph

C. Aqueous humour

D. Vitreous humour

Ans. C

19. Which of the following has monocular vision?

A. Owl

B. Monkey

C. Tiger

D. Frog

Ans. D

20. Feco surgery is done in-

A. Ear

B. Eye

C. Skin

D. Tongue

Ans. B

Answer in a single word or sentence

1. Name the three layers of human eye.

Ans. Sclera, choroid and retina

2. What is the other name of blind spot?

Ans. Optic disc

3. Which portion of human eye protects it from mechanical injury by dust particles?

Ans. Conjunctiva

4. What is the main function of human eye?

Ans. Vision.

5. What is sclera?

Ans. Sclera is the outermost protective layer of human eye.

6. Which nerve connects human eye with the brain?

Ans. Optic nerve

7. Through which opening does light enter into the eyeball?

Ans. Pupil

8. Which part of eyeball makes the pupil narrow or wide?

Ans. Iris

9. In which organ do you find cornea?

Ans. Eye

10. Which protective layer of eye becomes transparent to form the cornea?

Ans. Sclera

11. What is the function of the fluid present in the intermediate chamber between lens and retina of the eyeball?

Ans. The fluid present in the intermediate chamber between lens and retina is vitreous humour which helps to absorb shocks to the eye and maintains the shape of the eye.

12. Which parts of the body protect the eyes from mechanical injury and air borne particles?

Ans. The two eyelids protect the eyes from mechanical injury and air borne particles.

13. Which type of lens is used to correct myopia? 

Ans. Concave lens

14. Which type of lens is used to correct hypermetropia?

Ans. Convex lens

15. At which minimum distance does an object comes under the range of distant vision?

Ans. An object at a minimum distance of 6 metre comes under the range of distant vision.

16. In which eye problem, a person faces difficulty in viewing objects placed at a longer distance?

Ans. Myopia

17. In which eye problem, a person faces difficulty in viewing objects placed at a close distance?

Ans. Hypermetropia

18. Name an ageing-related eye disease.

Ans. Presbyopia

19. Which type of lens is used to rectify presbyopia?

Ans. Bifocal lens

20. Which protective layer is directly connected to the eyeball?

Ans. Conjunctive

21. In which disease the protein of lens is degraded?

Ans. Cataract

22. What are the pigments of rod and cone cells?

Ans. Pigmnent of rod cell is rhodopsin and pigment of cone cell is iodopsin.

23. What are the components of tear?

Ans. The components of tear are water, minerals, amino acid, antibody and lysozyme.

24. Why image is not formed in the blínd spot?

Ans. Due to the absence of light sensitive rod and cone cells image is not formed in blind spot.

Fill in the blanks

1. Retina is composed of rod and ……… cells.

Ans. Cone

2. Other than human being owl has …….. vision.

Ans. Binocular

3. Image of any visible object is formed on the ……… of eye.

Ans. Retina

4. Rod cells contain ……. pigments.

Ans. Rhodopsin

5. The concave spot of retina from which the optic nerve emerges is called …….. spot.

Ans. Blind

6. The centre of retina lying opposite to the pupil of eye is called …….. spot, where the brightest image is formed.

Ans. Yellow

7. The 1/6th part of sclera in front of the eye remains transparent, which is called ………

Ans. Cornea

8. The protective layer, just below the sclera of eye is called ………

Ans. Choroid

9. The cavities of skull in which the two eyeballs are lodged are called ……..

Ans. Orbit

10. The thin and transparent fibrous layer above the cornea is called ……..

Ans. Conjunctiva

11. The faintly saline watery discharge from eye is called ……..

Ans. Tear

12. At the centre of the yellow spot there is a tiny depression called …….

Ans. Fovea čentralis

13. The gel-like substance present in between the lens and retina is known as …….. humour.

Ans. Vitreous

14. In ……… disease, the lens become opaque.

Ans. Cataract

15. Loss of accommodation capacity of lens, due to ageing, results into ……… disease.

Ans. Presbyopia

16. The process of necessary adjustment of focal length of the lens in human eye is called ………

Ans. Accommodation

TOPIC – 5

LOCOMOTION AS A TYPE OF RESPONSE IN ANIMALS

SUMMARY

• Movement of the whole organism from one place to another is termed as locomotion. Animals move from one place to another place due to various reasons. Some of the reasons are-search of food, to protect itself, search of habitat, search of mate or reproduction, etc.
• Amoeba moves through pseudopodia, Paramoecium uses cilia, Euglena uses flagella for locomotion.
• Fishes swim by the help of ‘V’ shaped myotome muscles and paired or unpaired fins.
• Birds use feathers i.e. remiges of wing and rectrices of tail and flight muscles like pectoralis major, coracobrachialis and pectoralis minor for flight.
• Locomotion in human is termed as bipedal locomotion. This bipedal locomotion involves movement by two rear limbs or legs. Semicircular canal of inner ear and cerebellum helps in body balance during movement.
• Movable joints and skeletal muscles have huge importance in human locomotion. The synovial fluid present in joint prevents friction. Examples of synovial joints are-ball and socket joint, hinge joint, pivot joint, etc. Example of hinge joint is the joint of knee and elbow. Example of ball and socket joint is hip and shoulder joint.
• In flexion movement, two bones come near each other and in extension movement two bones moves distant from each other. The movement of any part away from the midline of the body is abduction and the movement towards the midline of the body is adduction. Rotation refers to movements made about the longitudinal axis and in the transverse plane. Different types of muscles help in these types of movements. Example-Biceps (flexor muscle), triceps (extensor muscle), dDeltoid (abductor muscle), adductor longus (adductor muscle).

Long Answer Type Questions

1. Briefly explain the driving forces of locomotion.

Or, State the importance of locomotion in living organisms.

Similar question, A resting animal attempts to move. Mention four probable reason behind it.

Ans. Driving forces of locomotion

The driving forces of locomotion are mentioned below.

1. Search of food: Unlike plants, animals are not capable of synthesising their own food. Therefore, animals have to roam around in search of food resources.
2. Escaping predation: Among animals, a prey-predator interaction continues all the time. Here, the aggressor is called the predator and the victims are called the preys. To avoid predation, preys have to flee from the predator. Therefore, locomotion is essential for preys to escape predation.
3. Migration: Due to environmental changes, various species move from one place to another, this is called migration. To avoid natural calamities, epidemic and other adversities, animals migrate to favourable places. This is a driving force of locomotion. For example, during rain, ants move upward in search of a dry habitat.
4. Searching for favourable habitat: Animals always look out for places with adequate food, water, ambient temperature, light, etc. This is also a purpose of animal locomotion.
5. Searching for mating partner and favourable mating place: Animals and a few plants perform locomotion in search of favourable places for reproduction. Animals roam around in search of suitable mating partners for successful reproduction.

2. How is locomotion dependent upon movement? State the differences between movement and locomotion.

Ans. Dependence of locomotion on movement

Locomotion is a process by which an organism changes its overall position in response to a stimulus or spontaneously. Whereas, the physical activity by which an organism move any of its body parts either spontaneously or in response to stimulus without changing its position, is called movement. A living form has to move its organs or cellular components in order to perform locomotion. Therefore, locomotion without movement is impossible but movement of organs is completely independent of locomotion.

Differences between movement and locomotion

Features	Movement	Locomotion
1. Change in position	Does not occur	Occurs
2. Involvement of organs	Limited to certain body parts	Whole body is involved
3. Interrelation	Movement is independent of locomotion	Locomotion is dependent on movement
4. Concerned organisms	Both plants and animals perform movement	Generally animals perform locomotion
5. Purpose	To perform several bio-mechanical functions	To search food, shelter, sex- partners and avoiding predation

3. Briefly describe the method of amoeboid movement.

Or, Describe the role of pseudopodia in locomotion of Amoeba. Distinguish between cilia and flagella.

Ans. Amoeboid movement

The method of amoeboid movement is mentioned here.

[1] The locomotory organ of Amoeba is pseudopodium. Density of cytosol changes within the cell body of an Amoeba by external stimulation. Cytosol with lower density moves faster than the denser portion. As the cytosol flows to hit the cell membrane, it protrudes to develop a pseudopodium. There are numerous pseudopodia developed in an amoeboid cell. [2] The tip of these pseudopodia attach with the substratum and cytosol continues to flow into them. [3] Gradually the whole protoplasm flows towards the direction of the pseudopodia and the posterior portion of the cell retracts accordingly. This type of movement by pseudopodia is called amoeboid movement.

Differences between cilia and flagella

Features	Cilia	Flagella
1. Occurrence	Present all along the outer surface of the cell	Emerge from one or two positions of the cell surface
2. Nature	Very fine and tiny	Comparatively thick and long
3. Function	Help in locomotion and guide food particle into the cellular mouth	Help in locomotion

4. Briefly describe the locomotory mechanism of Euglena. Mention the differences between locomotion in Amoeba and Euglena.

Ans. Locomotory mechanism of Euglena

The locomotory organ of Euglena is a flagellum. This is a microscopic, long and fine filamentous cytoplasmic projection. Euglena moves in water by beating of the flagellum, therefore this movement is called flagellar movement. The locomotory mechanism of Euglena is described ad follows-[1] Euglena beats its flagellum sidewise like a whip or rotates it around the longitudinal axis. [2] Movement of the flagellum generates turbulence in water and Euglena moves in opposite to its flagellum. [3] Euglena has a photosensitive eyespot. This helps it to sense light and guide it during locomotion towards the illuminated zone of the water body.

Differences between locomotion of Amoeba and Euglena

Features	Locomotion in Amoeba	Locomotion in Euglena
1. Locomotory organ	Pseudopodium	Flagellum
2. Medium of locomotion	Solid substratum in water bodies	Liquid medium
3. Method of locomotion	Amoeboid movement	Flagellar movement
4. Type of locomotory organ	Finger-like protoplasmic projections of different size and shape	Fine filamentous cellular outgrowths with internal cytoskeleton

5. Briefly describe the method of locomotion in Paramoecium. Mention few ciliated cells other than Paramoecium.

Ans. Locomotary mechanism of Paramoecium

The locomotory organs of Paramoecium are cilia. These are tiny, very fine and densely arranged filamentous structures present all over the outer surface of its cell body. The method of locomotion in Paramoecium through cilia is mentioned here.

[1] All cilia show a synchronised whiplash movement. The first phase of this movement is the effective stroke, during which the cilium bends sharply in one direction. [2] Effective stroke is followed by a slow recovery stroke during which the cilium curls back loosely to its previousdirection. [3] By the coordinated movement of all cilia, a continuous wave moves across the ciliated cell surface. This ciliary wave applies a thrust in the surrounding liquid medium and pushes the Paramoecium through it. This type of movement is known as ciliary movement.

Ciliated cells other than Paramoecium

Other than Paramoecium, Vorticella is another unicellular organism that possesses cilia. Among multicellular organisms, the cells of inner lining of trachea, olfactory cells of nose and hair cells of internal ear have cilia.

6. Describe with diagram, the mechanism of locomotion in fish.

Ans. Mechanism of locomotion in fish

The locomotory organs of fish are its fins. Besides these, myotome muscles and swim bladder also help in locomotion. The method of locomotion in fish is described here-[1] Fish has seven fins, of which pectoral and pelvic fins are paired whereas dorsal, anal and tail fins are unpaired. Role of each of these fins are mentioned as follows-[A] Pectoral and pelvic fins help the fish in going up and down in water. These fins also keep the fish steady at the floor of the water body during rest. [B] Dorsal fin and anal fin keep the fish steady and prevents it from rollover during swimming. [C] Tail fin beats to create a thrust in water to move the fish forward. It also helps it to change direction during swimming. [2] ‘V’ shaped myotome muscles of a fish, present at two sides of the vertebral column contract alternately in a synchronised fashion. This muscular action creates a lateral undulating movement in its body that helps the fish in swimming. [3] Swim bladder of a fish maintains its buoyancy by making instantaneous and voluntary changes. in gas volume and thereby helps it to stay at different levels of water.

7. Describe the roles of different flight-assisting body parts of birds.

Ans. Role of different flight-assisting body parts of birds

Birds are primary volant animals. Most of the birds perform locomotion by flight. The role of different flight-assisting body parts of birds are explained here-[1] Birds have spindle- shaped body, which helps to overcome air resistance. [2] The bones of birds are hollow inside, hence are very light. These bones are called pneumatic bones, which keep the body lighter and thus facilitate flight. [3] Lungs of birds are associated with 9 air sacs. These sacs hold extra air to reduce specific gravity and supply oxygen during high flight. [4] The forelimbs of birds are modified into wings. It is outwardly convex and inwardly concave. This shape facilitates in holding air during flight. [5] The edge of each wing has 23 and the edge of tail has 12 large ore-shaped flight feathers. These are called remiges and rectrices respectively. The feathers have barbs, barbules and interlocking hooks, which keep the feather intact even in heavy air thrust. [6] To beat continuously, the wings are fitted with strong flight muscles. Pectoralis major, pectoralis minor and coraco brachialis are the three flight muscles, which help in flight of birds.

8. Describe the mechanism of bipedal locomotion in man.

Ans. Bipedal locomotion in man

Human locomotion occurs by bipedal movement. Two legs take part in this locomotion hence it is called bipedal locomotion. Leg bones, bone joints and various leg muscles act in a coordinated fashion in this locomotion. The mechanism of bipedal locomotion is described here-[1] At first, the upper portion of the body tends to move forward while the two legs remain anchored on ground. [2] As the upper portion approaches forward, it tends to fall. To avert it, one leg, for instance, left leg moves forward and places the foot ahead. At this moment, the right leg holds, the body weight. [3] As the left foot touches ground, the right knee folds and the heel is lifted. With this movement, upper portion of body progresses forward and shifts its weight to left leg. [4] Now, the right toe is lifted from the ground and the foot is placed ahead of the left leg. In this process, the two legs alternately move up and down and hence, move forward to aid in walking. [5] To maintain body balance, two hands swing forward and backward alternately. When one leg moves forward the opposite hand extends. [6] The cerebellum and the semi-circular canals of internal ear also play important roles in keeping body balance during bipedal movement.

9. What is meant by movable or synovial joint? Describe it in brief.

Ans. Movable or synovial joint

The bone joint in which the bones are articulated in a movable manner and offers some degree of free movement is called movable joint. The point of articulation between two bones of a movable joint has a thin space, which remains filled with synovial fluid. Therefore, this type of joint is also called synovial joint.

Description of movable or synovial joint

The description of movable or synovial joint is given here.

[1] In this joint, the articulated ends of the bones remain attached to each other by thin but strong ligaments. [2] The heads of the bones remain coated with a thin fibrous tissue membrane called synovial membrane. [3] The fine space present in between the membrane-coated ends of the two bones is known as synovial space. [4] The space remains filled with an aqueous lubricating fluid called synovial fluid. [5] Synovial fluid protects the bone ends against frictional wearing and supplies nutrition to the surrounding tissues. [6] The ends of bones, are covered by thick cartilaginous tissue, called articular cartilage. It allows the bones to glide over each other with minimum friction. [7] There are different types of movable joints-ball and socket joint, hinge joint, angular joint, saddle joint, pivot joint, etc.

10. Give a brief description of the mechanism with examples of human skeletal muscles, involved in [1] Flexion, [2] Extension, [3] Abduction, [4] Adduction and [5] Rotation.

Ans. Action of some human skeletal muscles

Muscular action	Muscle involved	Mechanism	Example
1. Flexion	Flexor	As the muscle contracts, two bones fold and come close to each other.	Biceps of hand
2. Extension	Extensor	As the muscle contracts, two folded bones move away from each other to extend the concerned limb.	Triceps of hand
3. Abduction	Abductor	As the muscle contracts, the concerned limb moves away from the central axis of the body.	Deltoid of back
4. Adduction	Adductor	As the muscle contracts, the concerned limb moves close to the central axis of the body.	Latissimus dorsi of back
5. Rotation	Rotator	As the muscle contracts, the concerned organ rotates around another organ.	Sternocleidomastoid of neck

Short Answer Type Questions

1. What is locomotion?

Ans. Locomotion is a physical activity by which an organism changes its overall position in response to a stimulus or spontaneously.

2. What is meant by response in animals?

Ans. Response in animals means the movement of body parts or changing the overall position by an animal, involving the activity of muscles and bones.

3. What are pseudopodia?

Ans.Pseudopodia are temporary finger-like protrusions of protoplasm with cell membrane from the surface of amoeboid cells for the purpose of feeding and locomotion.

4. What are cilia?

Ans. Cilia are minute, numerous hair-like projections emerging from the surface of some unicellular organisms, which perform rhythmic beating for locomotion.

5. What are flagella?

Ans. Flagella are fine, slender, whip-like projections of some unicellular organisms, used for the purpose of swimming.

6. What does amoeboid movement mean?

Ans.Amoeboid movement is a locomotory movement of unicellular organisms, executed by means of pseudopodia. Protozoans like Amoeba and blood cells like neutrophils perform amoeboid movement.

7. How does Paramoecium perform ciliary movement?

Ans. Paramoecium has numerous densely arranged cilia along its cell membrane. All its cilia beat in a coordinated manner to create an undulating wave along the cell surface. This ciliary wave helps it to swim in the water bodies.

8. What is ciliary movement?

Ans. The locomotion of unicellular organisms by rhythmic beating of cilia beating in liquid medium is called ciliary movement. Paramoecium, Vorticella, etc. perform ciliary movement.

9. What is flagellar movement?

Ans.The locomotion of a unicellular organism by whipping or rotating of flagella in any liquid medium is called flagellar movement. Euglena, Trypanosoma, etc. perform flagellar movement.

10. What is myotome muscle?

Ans.The ‘V’ shaped muscle present on two sides of vertebra of fish extending from head to tail is called myotome muscle. These muscle helps in swimming.

11. Mention the location of myotome muscles. State their functions.

Ans. Location of myotome muscles: Myotome muscles are located at the two lateral sides of the body of a fish, extending from the back of operculum to the base of the tail fin.

Functions of myotome muscles: These muscles at lateral sides, contract and expand alternately in a synchronised manner to create an undulating movement of the body. The thrust that is created, helps the fish to move forward in water.

12. Mention the roles of fins of fish.

Ans.Fins of fish perform the following functions- [1] Pectoral and pelvic fins help the fish to move up and down in water. [2] Dorsal fins keep the body steady and prevent rolling over. [3] Tail fin helps in propelling the fish through water and changing direction during locomotion. [4] Anal fin maintains the stability of the fish in water, while swimming.

13. What would have happened to a bony fish if it had not developed any paired fin?

Ans.If a bony fish had not developed any of its paired fins, like pectoral and pelvic fins, it would not have been able to move up and down in water and cannot remain steady in a stationary condition.

14. What would have happened to a bony fish if it had not developed a swim bladder?

Ans.If a bony fish had not developed a swim bladder, it would fail to maintain its buoyancy. In this situation, it could not go at different depths of the water body and not even stay stationary at a certain depth. If it had to survive, it would have to stay at the floor of the water body.

15. Mention the functions of the tail fin of a fish.

Functions of tail fin of a fish are as follows- [1] Tail fin gives the ultimate thrust on water to push the body forward (propulsion). [2] Tail fin controls the direction of movement of the fish while swimming.

16. What are flight feathers? Mention their types.

Ans.Flight feathers: The larger feathers, which are arranged along the inner edge of wings and end of the tail of a bird, are called flight feathers.

Types of flight feathers: The flight feathers are of two types-the remiges present in wings and the rectrices along the end of tail.

17. What are flight muscles?

Ans. The voluntary muscles attached to the wings and tail of birds, which help in beating of wings and rotating of tail during flight, are called flight muscles. Example-Pectoralis major, pectoralis minor, coracobrachialis.

18. How do the feathers remain intact in air pressure?

Ans.A feather has numerous lateral filamentous barbs. Each barb develops lateral barbules and microscopic hooks from both the sides. These hooks interlock the barbules and thereby the barbs as well. Due to this cross interlocking of the barbs and barbules, the feathers remain intact in wind pressure. If any portion of it splits, it rejoins at once at the two opposing hooks that encounter each other.

19. Differentiate between remiges and rectrices.

Ans. Difference between remiges and rectrices are-

Features	Remiges	Rectrices
1. Position	These are feathers of wing of birds	These are feathers of tail of birds
2. Number	These are generally higher in number, pigeon have 23 remiges in each wing	These are fewer in number, Pigeon has 12 rectrices
3. Function	Helps mainly in flight by producing pressure to air	Helps in body balance and to change direction

20. Why is human locomotion called bipedal locomotion?

Ans.The locomotory organs of human are two legs. By continuous and synchronised movement of these two legs, a man moves from one place to an other. Therefore, human locomotion is called bipedal locomotion.

21. What is skeletal muscle? Give two examples of muscle helping in locomotion.

Ans. Skeletal muscle: The muscle attached to bones by tendon and helps in locomotion are called skeletal muscle.

Example: Biceps femoris and gastrocnemius.

22. Mention how the skeletal muscles help in human movement and locomotion.

Ans.Skeletal muscles remain attached to different movable bones of different limbs. By the voluntary contraction of these muscles the concerned limbs move. Thus, skeletal muscles help in human movement and locomotion.

23. Why is the movable bone joint called synovial joint?

Ans. In between the joining ends of two bones of a movable joint, there remains a thin space. A lubricating fluid is present in it, called synovial fluid. Therefore, this type of bone joint is called synovial joint.

24. What are the functions of synovial fluid?

Ans.The functions of synovial fluid are- [1] Synovial fluid prevents the decay of bones due to friction. [2] Synovial fluid nourishes the cartilage present in the joint.

25. What is tendon?

Ans. A tendon is a fibrous connective tissue which attaches muscle to bone. These are generally bright white in colour.

26. What is hinge joint?

Ans.The bone joint, in which the bones move at an angle of 180° in a single plane, is called hinge joint. Example-Elbow and knee are hinge joints.

27. Mention the characteristics of hinge joint.

Ans. Characteristics of hinge joint are as follows- [1] One bone of this joint has a round head and the other, has a concave head. [2] The bones move at a maximum angle of 180° only in one plane.

28. What is ball and socket joint?

Ans. The movable joint in which one bone with a partial spherical head is articulated with a cup-shaped cavity of another bone, is called ball and socket joint. This allows multidirectional movement and rotation. This type of joint is present in shoulder and hip.

29. Mention the characteristics of ball and socket joint.

Ans.Characteristics of ball and socket joint are as follows-[1] One bone of this joint has a spherical head (ball) and the other bone has a cup shaped end (socket). [2] In this joint, the socket remains fixed but the ball-ended bone can rotate almost at any direction.

30. What is rotator muscle?

Ans.The muscle, which helps an organ to rotate around a central axis, is called rotator muscle. Example-Piriformis muscle of the lower limb.

31. What is flexor muscle?

Ans. The muscle, which contracts to fold a limb, is called flexor muscle. Example-Biceps muscle of upper arm.

32. What is extensor muscle?

Ans.The muscle, which contrasts to extend a folded limb, is called extensor muscle. Example- Triceps muscle of the upper arm.

33. What is abductor muscle?

Ans.The muscle, which contracts to pull a limb away from the body axis, is called abductor muscle. Example-Gluteus maximus muscle of the hip, deltoid muscle of shoulder.

34. What is adductor muscle?

Ans. The muscle, which contracts to pull a limb close to the body axis, is called adductor muscle. Example-Adductor longus muscle of the thigh.

Very Short Answer Type Questions

Multiple Choice Questions & Answers [MCQ]

1. The overall change in position of an organism from one place to another is called-

A. Movement

B. Locomotion

C. Transportation

D. Displacement

Ans. B

2. Which of the following organisms performs locomotion by means of pseudopodia?

A. Amoeba

B. Cockroach

C. Paramoecium

D. Butterfly

Ans. A

3. Paramoecium performs locomotion by-

A. Flagella

B. Cilia

C. Pseudopodia

D. Muscular foot

Ans. B

4. ……….. performs locomotion by flagella.

A. Cockroach

B. Euglena

C. Paramoecium

D. Amoeba

Ans. B

5. Number of fins found in bony fishes is-

A. One

B. Five

C. Seven

D. Nine

Ans. C

6. Myotome muscles are present in-

A. Fishes

B. Bats

C. Dragon flies

D. Pigeons

Ans. A

7. While swimming, which of the following helps in changing direction in fishes?

A. Caudal fin

B. Dorsal fin

C. Anal fin

D. Pelvic fin

Ans. A

8. Which of the following is the locomotory organ in human body?

A. Hand

B. Leg

C. Forelimb

D. Tail

Ans. B

9. Which of the following organisms is not capable of locomotion?

A. Coral

B. Cockroach

C. Spider

D. Snail

Ans. A

10. The organ which helps fishes to float in water, is called-

A. Fins

B. Air bladder

C. Operculum

D. Lateral line sense organ

Ans. B

11. A plant, which is capable of locomotion, is-

A. Fern

B. Cuscuta

C. Chlamydomonas

D. Mucor

Ans. C

12. An animal, which is not capable of locomotion, is-

A. Starfish

B. Earthworm

C. Sponge

D. Hydra

Ans. C

13. Where do you find ball and socket joint?

A. Shoulder

B. Knee

C. Thumb

D. Elbow

Ans. A

14. In which of the following, a hinge joint is seen?

A. Waist

B. Shoulder

C. Elbow

D. Skull

Ans. C

15. In which of the following, an immovable joint is seen?

A. Waist

B. Shoulder

C. Skull

D. Elbow

Ans. C

16. The type of movement, which is seen in human, is called-

A. Bipedal movement

B. Amoeboid movement

C. Ciliary movement

D. Flagellar movement

Ans. A

17. Which of the following animals performs locomotion by means of swimming?

A. Hydra

B. Sponge

C. Fish

D. Amoeba

Ans. C

18. Which of the following animals performs locomotion by means of flight?

A. Earthworm

B. Snail

C. Bird

D. Lizard

Ans. C

19. Locomotory organ of fish-

A. Fin

B. Swim bladder

C. Lateral line sense organ

D. Undulating membrane

Ans. A

20. The bone, which is absent in hands, is-

A. Radius

B. Ulna

C. Humerus

D. Femur

Ans. D

21. Sunlight plays an important role in movement of which animal?

A. Amoeba

B. Paramoecium

C. Both A and B

D. Euglena

Ans. D

22. Tibia, femur and patella unite at-

A. Pelvic girdle

B. Knee

C. Elbow

D. Ankle

Ans. B

23. Hip joint is the union of-

A. Femur and pelvic girdle

B. Femur and scapula

C. Humerus and scapula

D. Radius and ulna

Ans. A

24. Shoulder joint involves-

A. Scapula and humerus

B. Humerus and ulna

C. Femur and tibia

D. Pelvic girdle and femur

Ans. A

25. Ligaments, tendons and bone joints are part of the-

A. Respiratory system

B. Musculature

C. Skeletal system

D. Circulatory system

Ans. C

26. Number of remiges present in each wing of pigeon is-

A. 11

B. 13

C. 19

D. 23

Ans. D

27. Number of rectrices present in tail of pigeon is-

A. 6

B. 8

C. 12

D. 16

Ans. C

28. Which of the following muscles is not a flight muscle of pigeon?

A. Pectoralis major

B. Pectoralis minor

C. Myotome

D. Coraco brachialis

Ans. C

29. Myotome muscles are seen in-

A. Human body

B. Fish

C. Whale

D. Toad

Ans. B

Answer in a single word or sentence

1. Name the locomotory organ of Amoeba.

Ans. Pseudopodia

2. What is the locomotory organ of Euglena?

Ans. Flagellum

3. What are the locomotory organs of a fish?

Ans. Fins

4. What are the locomotory organs of a bird?

Ans. A pair of wings and two legs are the locomotory organs of a bird.

5. Name the muscle that helps in locomotion of a fish.

Ans. Myotome muscles

6. Name the paired fins of a fish.

Ans. Pectoral and pelvic fins

7. Name the unpaired fins of a fish.

Ans. Caudal, dorsal and anal fins

8. Which fin helps a fish to change its direction during swimming?

Ans. Caudal or tail fin

9. Which organ of a fish helps it to float in water?

Ans. Swim bladder

10. What will happen to a fish if all its fins are tied with a thread?

Ans. A fish will not be able to swim and keep its balance in water, if all its fins are tied with a thread.

11. When does Amoeba grow its pseudopodia?

Ans. During movement and food capturing, Amoeba grows its pseudopodia.

12. Which type of locomotion does an adult human perform?

Ans. Bipedal locomotion

13. Name a voluntary muscle.

Ans. Biceps

14. Which type of muscle is biceps?

Ans. Flexor muscle

15. Name an extensor muscle.

Ans. Triceps

16. How do you denote the point of contact between two bones?

Ans. The point of contact between two bones is called the bone joint.

17. Name the structure, which connects two bones in a bone joint.

Ans. Ligament

18. Where do you find hinge joints?

Ans. We find hinge joints in elbow and knee.

19. Where do you find ball and socket joints?

Ans. We find ball and socket joints in shoulder and hip.

20. Which characteristic feature of muscle fibres helps in movement and locomotion?

Ans. Contractibility of muscle fibres helps in movement and locomotion.

21. Which type of joint is the knee joint?

Ans. Hinge joint

22. Which fins help a fish to move up and down in water?

Ans. Pectoral and pelvic fins

23. Name the ‘V’ shaped muscles present at both sides of the lateral line of a fish.

Ans. Myotome muscles

24. Which muscle helps in extending a folded limb?

Ans. Extensor muscles

25. Which muscle helps to rotate a body part?

Ans. Rotator muscles

26. Which muscle does help to move a limb away from the axis of the body?

Ans. Abductor muscles

27. Name the flight feathers present along the posterior edge of wings of a bird.

Ans. Remiges

28. Name the large feathers present at the tail end of a bird.

Ans. Rectrices

29. Name a unicellular organism having a photosensitive eyespot.

Ans. Euglena

30. Which flight muscle helps a bird to move downward during flight?

Ans. Pectoralis major

31. Which flight muscle helps a bird to move upward during flight?

Ans. Pectoralis minor

32. Which part of internal ear helps to maintain body balance?

Ans. Semicircular canals

Fill in the blanks

1. One of the objectives of ……….. is the search of food.

Ans. Locomotion

2. Chlamydomonas is a ……….. capable of locomotion.

Ans. Plant

3. The locomotory organ of Amoeba is ……….

Ans. Pseudopodium

4. Paramoecium moves in ………. direction to the movement of cilia.

Ans. Opposite

5. The ………. of Euglena helps in determining the direction of its movement.

Ans. Eyespot

6. The …………. present in Euglena can sense the presence of sunlight.

Ans. Eyespot

7. The swim bladder of bony fish helps to maintain its ……….

Ans. Buoyancy

8. ………. are the main locomotory organs of fishes.

Ans. Fins

9. The ………… muscles of fish help it in swimming.

Ans. Myotome

10. ……….. fin of fish gives it stability in water.

Ans. Anal

11. Pectoral and ………. fins are paired fins of a fish.

Ans. Pelvic

12. The muscles, which help a bird in flying are called …….. muscles.

Ans. Flight

13. During bipedal locomotion, two ……… help in maintaining the stability of human body.

Ans. Hands

14. Articular hyaline cartilage is present in ………  joints.

Ans. Synovial

15. In a hinge joint, the articulated bones can move at an angle of ……… in a single plane.

Ans. 180°

16. The hip joint involves pelvic girdle and ……….

Ans. Femur

17. The muscles helping in the movement of bones are called ………. muscles.

Ans. Skeletal

18. Sternocleidomastoid is a muscle that helps in ………. movement.

Ans. Rotational

19. ………… muscle of hand contracts to fold the arm.

Ans. Biceps

20. ………. muscle helps in extension of the arm.

Ans. Triceps

21. ……….. muscle is ‘V’ shaped.

Ans. Myotome

22.  Elbow joint is a ………. joint.

Ans. Hinge

State true or false

1. Movement of any limb away from the body axis is called flexor.

Ans. False

2. Joints of knee and elbow are examples of hinge joint.

Ans. True

3. Synovial fluid protects the movable bone ends against friction.

Ans. True

4. Fins of birds help in flight.

Ans. False

5. The tail feathers of birds are called remiges.

Ans. False

6. During locomotion in man, cerebellum helps in maintaining body balance.

Ans. True

7. Tail fin of fish helps in changing direction during swimming.

Ans. True

8. Biceps is example of extensor muscle.

Ans. False

9. Fins with fin rays are seen only in bony fishes.

Ans. True

10. Eyespot is present in Amoeba.

Ans. False

11. Flagella help in locomotion of Amoeba.

Ans. False

12. Paramoecium is a sessile organism.

Ans. False

13. Corals are incapable of locomotion.

Ans. True

14. The skull bones are movably articulated with each other.

Ans. False

15. In ball and socket joint, the bones can move in more than two axis.

Ans. True

16. Flagella is the locomotary organ of Paramoecium.

Ans. True

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