JKBOSE 10th Class Science Solutions Chapter 12 Control and Coordination
JKBOSE 10th Class Science Solutions Chapter 12 Control and Coordination
JKBOSE 10th Class Science Solutions Chapter 12 Control and Coordination
Jammu & Kashmir State Board JKBOSE 10th Class Science Solutions
J&K class 10th Science Control and Coordination Textbook Questions and Answers
BASIS AND BASICS
◆ Control and coordination are the functions of the nervous system and hormones in our bodies.
◆ The responses of the nervous system can be classified as reflex action, voluntary action or involuntary action.
◆ The nervous system uses electrical impulses to transmit messages.
◆ Neuron is the functional unit of nervous sytem which responds to stimuli by electrical impulses.
◆ The Central Nervous System (CNS) consists of the brain and the spinal cord.
◆ Brain is the highest co-ordinating centre of the body.
◆ The nervous system gets information from our sense organs and acts through our muscles.
◆ Chemical coordination is seen in both plants and animals.
◆ Nastic movements found in plants are non-directional movements. It is determined by the structure of the responsive organ and not in the direction of the stimulus.
◆ Tropic Movement. It is a type of movement found in the plants which are caused by the external stimulus.
◆ Phototropism. The movement of a part of the plant in response to light is called phototropism.
◆ Geotropism. It is the movement of a part of the plant in response to gravity, e.g., the roots of plant move downwards due to gravity.
◆ Chemotropism. The movement of a part of the plant in response to chemical stimulus is called chemotropism.
◆ Hormones produced in one part of an organism move to another part to achieve the desired effect. A feedback mechanism regulates the action of the hormones.
◆ Endocrine glands secrete the hormones directly into the blood.
◆ Exocrine glands are glands with ducts which pour their secretion at the site of action.
◆ Insulin is the hormone produced by β-cells of islets of Langerhans which controls sugar metabolism.
◆ Phytohormones. These are plant hormones which bring about co-ordination in plants.
IMPORTANT TERMS AND FACTS TO MEMORISE
⇒ Phytohormones. These are the hormones secreted by plants to perform various functions.
⇒ Nastic movements. When the stimulus does not produce any movement in plants.
⇒ Phytochrome. These are special pigments which respond to the photoperiod.
⇒ Ganglion. The group of cell bodies of nerve cells is called ganglion.
⇒ Reflex action. The involuntary actions towards emergency situations.
⇒ Reflex arc. The path through which the signal travels during reflex action is called the reflex arc.
⇒ Spinal cord. Nerves from all over the body meet to form a bundle/cord on their way to connect with the hind brain is called as spinal cord.
⇒ Central nervous system. Brain and nerve cord together constitute the central nervous system.
⇒ Motor neurons. The neurons which carry the responses to the concerned organs.
⇒ Sensory neurons. The neurons which carry the message from sensory organs to brain.
⇒ Nerve impulse. The conduction of chemical or electric signals by nerve cells is called nerve impulse.
TEXT BOOK QUESTIONS (SOLVED)
Q. 1. What is the difference between reflex action and walking ?
Ans. Differences between a reflex action and walking
| Reflex Action | Walking |
|
1. It is spontaneous, involuntary response to a stimulus.
2. It is the response of the spinal cord.
3. Its intensity cannot be changed.
4. It increases the survival and protective values for an organism.
|
1. It is acquired through learning.
2. It is controlled by the brain (hindbrain).
3. Its intensity can be changed.
4. It is concerned with locomotion.
|
Q. 2. What happens at the synapse between two neurons ?
Ans. Synapse is a junction between terminal arborization of one axon and dendrites of adjacent neuron. There is a gap between the two called synaptic cleft. As the electrical impulse reaches the terminal knobs, they release chemicals called neurotransmitter. These chemicals cross the gap and start a similar electrical impulse in the dendrite of next neuron.
Q. 3. Which part of brain maintains posture and equilibrium of body ?
Ans. Cerebellum (Part of hind brain).
Q. 4. How do we detect the smell of an agarbatti (Incense stick) ?
Ans. Sensory information regarding smell is received by olfactory lobes of brain. As the air passes through the nasal chambers, the olfactory epithelial cells get stimulated and convey the information as electrical impulses to brain which have the power of interpretation.
Q. 5. What is the role of brain in reflex action ?
Ans. Reflexes which involve spinal cord are termed spinal reflexes. However,some reflexes involve brain where the thinking centres are located. Brain is the co-ordinating centre. Brain and spinal cord in coordination with each other control all voluntary and involuntary actions.
These reflexes are termed cerebral reflexes e.g. salivation at the sight of delicious food, closing of eyelids on exposure to flash light.
Q. 6. What are plant hormones ?
Ans. Plant hormones. These are chemical compounds secreted by plants which diffuse all around the other cells and regulate the activities. Plants hormones help to co-ordinate (i) growth (ii) development and (iii) responses to the environment.
Examples. Auxins, Gibberellins, cytokinin, Abscisic acid, ethylene.
Q. 7. How is the movement of leaves of sensitive plant is different from movement of a shoot towards light?
Ans. Sensitive plant show snastic movements. It is due to turgidity of cells. The movement of a shoot is a tropic movement.
| Movement of leaves of sensitive plant | Movement of a shoot towards light. |
|
1. It is a nastic movement.
2. The stimulus in this case is touch.
3. It is caused by sudden loss of water from the swelling at the base of leaves.
4. It is not growth movement.
|
1. It is tropic movement.
2. The stimulus is light.
3. It is caused by unequal growth on two sides.
4. It is growth movement.
|
Q. 8. Give an example of plant hormone that promotes growth.
Ans. IAA = Indole-3-Acetic Acid.
Q. 9. How do auxins promote growth of a tendril around a support ?
Ans. Auxins synthesised in the tip helps the cells to grow longer. Some plants like the pea plant climb up other plants or support by means of tendrils. These tendrils are sensitive to touch. When they come in contact with any support, the part of the tendril in contact with the object does not grow as rapidly as the part of the tendril away from the object. This causes the tendril to circle around the object and thus cling to it. It is due to accumulation of auxins.
Q. 10. Design an experiment to demonstrate hydrotropism.
Ans. Experiment to demonstrate hydrotropism
1. Take a porous pot and fill it with water.
2. Keep a few freshly germinated pea seedlings in a dried sand.
3. As the water is not available in sand the root growing will bend towards porous pot filled with water.
4. You will observe a hydrotropic curvature of the root as it grows towards water.
5. This bending of root show the movement as a response towards water.
Q. 11. How does chemical coordination take place in animals?
Ans. Chemical coordination. It is brought about by chemical messengers called hormones. They are secreted by endocrine glands (ductless glands). The hormones are carried by the blood to the site of action (target organs). The hormones are consumed during their action. Hormones provide wide ranging changes.
Q. 12. Why is the use of iodised salt advisable ?
Ans. Iodine is a mineral. It is found in the earth crust and in the drinking water. It is needed for the normal functioning of thyroid gland and the production of thyroxine hormone, which is very necessary for the normal physical and mental growth of the body. Thyroxine hormone also controls proper metabolism and use of proteins, carbohydrates and fats in the body. Deficiency of Iodine in the body causes the following problems:
(i) Thyroid gland is not able to work properly and produce sufficient amount of thyroxine. It causes enlargement of the gland, a condition called Goitre.
(ii) Due to deficiency of thyroxine hormone normal physical and mental growth does not take place.
Hence, to supplement iodine in the diet (food), iodized salt is advisable. Iodized salt supplies iodine for the normal functioning of the thyroid gland.
Q. 13. How does our body respond when adrenaline is secreted into blood ?
Ans. Adrenaline also called stress hormone is secreted by adrenal gland during emergency. It prepares the body to respond effectively. Following actions occur :
1. Heart beats faster so as to pump the blood to muscles which need more energy.
2. The blood supply to digestive system and skin is reduced due to contraction of muscles around these organs. This helps in diverting blood supply to muscles.
3. Breathing becomes fast.
4. It increases blood sugar.
All these responses together enable human body to face the stress and deal with emergency conditions.
Q. 14. Why are some patients of diabetes treated by giving injections of insulin?
Ans. Insulin hormone is secreted by Islets of Langerhans of pancreas. This hormone helps in regulating sugar level in the blood. Its deficiency results in high sugar level and cause many harmful effects.
Insulin cannot be given orally because it gets digested in the digestive tract, thus insulin is injected.
TEXT BOOK EXERCISES (SOLVED)
Q. 1. Which of the following is plant hormone ?
(A) Insulin
(B) Thyroxin
(C) Estrogen
(D) Cytokinin.
Ans. (D) Cytokinin.
Q. 2. The gap between two neurons is called :
(A) Dendrite
(B) Synapse
(C) Axon
(D) Impulse.
Ans. (B) Synapse.
Q. 3. The brain is responsible for :
(A) Thinking
(B) Regulating the heart beat
(C) Balancing
(D) All of above.
Ans. (D) All of above.
Q. 4. What is the function of receptors in the body? Think of situations where receptors do not work properly. What problems are likely to arise ?
Ans. Receptors. They are meant for receiving and detecting the information from environment. They are located in sense organs. They receive the information detected by tips of dendrites and convey them as electrical impulses.
If receptors do not detect the information, there will not be any co-ordination. It may lead to accidents. Body response will not be there.
Q. 5. Draw a labelled diagram of neuron and explain its function.
Or
Draw the structure of neuron and label the following on it.
Nucleus, Dendrite, Cell body and Axon.
Ans. Neuron (Nerve cell) [Fig.].
Functions. 1. Nerve cells are specialised for conducting information via electrical impulses from one part of the body to another part.
2. Dendrites acquire the information.
3. Axon conducts information as electrical impulse.
4. Terminal branches pass the information as chemical stimulus at synapse for onward transmission.
Q. 6. How does phototropism occur in plants ?
Ans. Phototropism.
It is an established fact that plants bend towards light when they are exposed to it from one side of long axis. The aerial parts are positively phototropic and the roots and other underground parts bend away from light. These movements are due to interaction of light and auxins. Auxins stimulate the cells to grow one side of shoot which is away from The unilateral growth causes bending of stem as tip grows more rapidly.
Q. 7. Which signals will get disrupted in case of spinal cord injury?
Ans. 1. Spinal cord mainly control reflex actions in the body. Spinal cord is made up of nerves which supply information to think about. Thus these actions will get disrupted in case of injury to spinal cord.
2. Sensation and movement are restricted.
Q. 8. How does chemical co-ordination occur in plants?
Ans. Chemical coordination in plants.
1. Plants do not have well organised nervous and muscular system, still they respond to stimuli and co-ordinate in the best possible way.
2. Different kinds of stimuli trigger the release of chemicals called plant hormones or phytohormones.
3. These phytohormones help to coordinate growth development and responses to the environment.
4. Auxins stimulate the cells to grow longer on one side of shoot in response to light thus it bends way. .
5. Gibberellins help in growth of stem
6. Cytokinins promote cell division.
7. Abscisic acid inhibits growth. It’s effects include wilting of leaves.
8. Ethylene helps in ripening of fruits.
Q. 9. What is the need for a system of control and co-ordination in an organism ?
Ans. Control and Co-ordination in the body is of two types i.e. nervous control and hormonal control. Nervous control is rapid. It takes place through electrical signals called nerve impulses. The hormonal control is through chemical messengers called hormones secreted by endocrine (ductless) glands and carried by blood to the target organs.
Q. 10. How are involuntary actions different from reflex action ?
Ans. The difference between involuntary actions and reflex actions are given below :
| Involuntary Actions | Reflex Actions |
| 1. They involve autonomic nervous system. | 1. They involve all parts of voluntary nervous system. |
| 2. They usually occur in response to internal stimuli. | 2. They operate against harmful stimuli, which are generally external and may cause injury. |
| 3. They are connected with functioning of internal body parts. | 3. They are connected with emergency. |
| 4. These are regulated by medulla (hindbrain). | 4. Reflex action is, generally, controlled by spinal cord. |
| 5. The speed of response is slower than reflex action. | 5. The speed of response is very fast. |
| 6. Example: Peristaltic movement in alimentary canal, beating of heart muscle. | 6. Example Removal of hand with jerk, when someone touches a hot object accidentally. |
Q. 11. Compare and contrast the nervous and hormonal mechanism for control and coordination in animals.
Ans. Differences between endocrine system and nervous system
| Endocrine System | Nervous System |
| 1. The action of endocrine system is often very diverse, affecting many cells and sometimes several organs found in different parts of the body. | 1. The action of nervous system is is limited to a few muscle fibres or gland cells of an organ or organ system. |
| 2. The system is not directly connected to organs or tissues under its control. | 2. The system is directly connected to tissues or organs under its control. |
| 3. It exerts its control through hormones or chemical regulators poured into circulatory system. | 3. Nervous system exerts its control through chemical stimulants poured directly over the tissues or organs. |
| 4. The information is transmitted slowly. | 4. The information is transmitted almost instantaneously. |
| 5. The system takes time to produce response. It, therefore, regulates those processes where the response is not obimmediately required. | 5. It controls process where an immediate response is required. |
| 6. The effect is long-lasting. | 6. The effect is short-lived. |
Q. 12. What is the difference between the manner in which movement takes place in a sensitive plant and the movement in our leg?
Ans. Movement of human leg is under the control of nervous system. It is under the direction of motor area which controls voluntary muscle of leg. The sensitive plant “Touch me not,’ moves its leaves in response to touch but without any regulation by nervous tissue and muscles.
ADDITIONAL IMPORTANT QUESTIONS
LONG ANSWER TYPE QUESTIONS
Q. 1. Describe the structure and function of human brain.
Ans. Parts of fore brain. Fore brain consists of a pair of olfactory lobes, cerebrum and diencephalon.
1. Olfactory lobes. They are concerned with sense of smell.
2. Cerebrum. Cerebrum is the largest part of brain. It consists of right and left cerebral hemispheres.
The intelligence and judgement depend on the coordinated and integrated activities of the neurons of different centres. Each cerebral hemisphere contains lateral ventricle.
Functions. Cerebrum relays impulses to all parts of the body. It also governs man’s mental activities i.e. reason, will, memory, emotions and intelligence. Subconscious or unconscious mind is also located in the cerebrum.
3. Diencephalon. Its cavity is called the 3rd ventricle.
Functions: 1. It controls metabolism.
2. It regulates functions of internal organs.
Mid brain. It consists of optic lobes and crura cerebri. Involuntary actions are controlled by the mid brain.
Hind brain. It consists of cerebellum, pons and medulla. It controls working of internal organs, voluntary actions maintaining posture and balance.
Q. 2. Draw section of human brain showing its structure.
Ans.
Q. 3. Describe the structure of a neuron.
Ans. Structure of neuron. The neuron or nerve cell is the structural and functional unit of the nervous system. It is highly modified for communication inside the body of an animal.
Cyton. The nerve cell is composed of a cell body called cyton and a long fibre called axon. Cyton contains a conspicuous nucleus. Cytoplasm has a number of granules as Nissl’s granules.
Dendrites. Numerous branched processes are seen in the periphery of the cell. These are called dendrons or dendrites, through which the nerve impulses are received from the neighbouring cells.
Axon. One of these processes is produced into a long unbranched fibre called axon through which the nerve impulses leave the cell. The free end of axon joins with the dendrite of another nerve cell. At this junction, a small gap called synapse is present. In the synapse, acetylcholine is secreted and the messages are transmitted chemically.
Each axon is covered by an inner coat called myelin sheath or medullary sheath. This covering is not continuous and is constricted at regular intervals. These constrictions are called nodes of Ranvier. Myelin sheath is covered by an outer coat known as neurilemma or sheath of Schwann. The nerve cell which has both myelin sheath and neurilemma is known as medullated nerve cell or fibre. If the cell does not contain these membranes, the nerve cell is said to be non-medullated.
Q. 4. Explain the reflex action by means of reflex arc with diagram.
Ans. In man and other vertebrate animals, there are two types of actions viz. voluntary and involuntary actions. The actions carried out and regulated by brain are voluntary actions. The actions carried out without direct concern of brain are involuntary actions. The involuntary actions are conducted by spinal cord and are known as reflex actions.
Reflex arc. For a reflex action, the path taken by a stimulus from some reception to one or more effectors is known as reflex arc. Once the sensory organ is excited by some stimuli, the message is carried by the sensory nerves to the spinal cord. From the spinal cord the directions carried by the motor nerve fibres to one or more effector organs. The whole action is completed instantaneously.
Examples. Some of the examples of reflex actions are blinking of eyes, sneezing, coughing in response to foreign particle that has entered in eye, nose, the throat respectively.
SHORT ANSWER TYPE QUESTIONS
Q. 1. List the components of Nervous system.
Ans. Nervous system
It consists of central nervous system, peripheral nervous system and autonomic nervous system.
Central nervous system. It consists of brain and spinal cord. It is the main controlling centre of the body.
Peripheral nervous system. It consists of cranial and spinal nerves. The autonomic nervous system consists of a special set of peripheral nerves that innervate organs like heart, lungs, digestive tract.
The autonomic nervous system can be divided into two divisions :
(a) Sympathetic system.
(b) Parasympathetic nervous system.
Q. 2. What is a synapse? What happens at the synapse ?
Ans. Synapse. Synapse is the close proximity of the axon of one neuron and the dendrite or cyton of another neuron with a gap. In a synapse, the transmitting cell is called the presynaptic cell and the receiving cell is termed the postsynaptic cell. A narrow gap, called synaptic cleft, separates the presynaptic cell from the postsynaptic cell. Hence, an action potential occurring in the membrane of the presynaptic cell cannot be directly transmitted to the membrane of the postsynaptic cell.
Q. 3. Draw a diagram showing structure of synapse.
Ans. Synapse.
Q. 4. Briefly explain a neuromuscular junction.
Ans. Neuromuscular junction. It is the point where a muscle fibre comes in contact with a motor-neuron carrying nerve impulses from the central nervous system. The impulses travel from the neuron to the muscle fibre by means of a neurotransmitter in the same way as the transmission of impulses across a synapse between two neurons.
Q. 5. What are the parts of the human peripheral nervous system?
Ans. The peripheral nervous system of man consists of nerves arising from the brain and the spinal cord. There are 12 pairs of nerves from the brain and 31 pairs of nerves from the spinal cord. The nerves that arise from the brain are called cranial nerves and that from the spinal cord, spinal nerves. These nerves may be sensory, motor or mixed type. These nerves carry impulses to and from various organs. These nerves control and coordinate the voluntary and involuntary functions of impulses.
Q. 6. What is reflex action? Give examples of reflex action.
Ans. Reflex action. Spontaneous, mechanical involuntary response by voluntary organs to a stimulus is called reflex action.
Examples of reflex action
(i) If the hand is suddenly pricked with needle, it is withdrawn immediately.
(ii) Watering of mouth on looking delicious dishes.
(iii) Closing of eyes in response to sudden flash light.
Q. 7. Explain reflex arc or reflex path.
Or
What will happen if you happen to step accidentally on a nail ?
Ans. Reflex arc. It is the pathway taken by the nerve impulse and response in a reflex action, i.e. from receptor organs likes skin or taste buds to the spinal cord and from spinal cord to the effector organs like muscles or salivary glands. If we happen to step accidentally on a nail, the foot is withdrawn immediately. It is due to reflex action or spinal reflex.
In such case the stimulus of a pointed object like nail is carried to the spinal cord by the sensory (afferent) nerve fibres to the grey matter of spinal cord through dorsal root. Now after the interpretation, the stimulus is transmitted to motor nerve fibres at the synapse. The motor (efferent) impulse is carried by motor nerve fibre through ventral root to the effector organ and response is made. In this case it is in the form of withdrawal of foot by the contraction of voluntary muscles. They behave involuntary during reflex action.
Q. 8. Define ‘nerve impulse’. Which structure in a neuron helps to conduct a nerve impulse ?
(i) towards the cell body?
(ii) away from the cell body ?
Ans. (a) Nerve impulse. The information passing through neurons in the form of electrical and chemical signals is called nerve impulse. Neurofibrils in the neuron help to conduct impulses.
(b) Neuron is structural and functional unit of nervous system. Dendrite carries the impulse to cell body and axon carries impulse away from cell body.
Q. 9. Name the five major senses of man.
Ans. Five major senses of man
1. Sense of hearing.
2. Sense of smell.
3. Sense of touch.
4. Sense of taste.
5. Sense of vision or sight.
Q. 10. List st different parts of the human nervous system.
Ans.
Q. 11. Write short note on meninges present around brain. Name the fluid present in the spaces in between meninges. Mention its function.
Or
How are brain and spinal cord protected ?
Ans. 1. Meninges (Sing. Meninx.) The protective membranes are present around brain. They are as follows:
(i) Duramater. It is outer, thick, non-vascular membrane present inner to bones of cranium.
(ii) Piamater. It is inner, thin, vascular membrane present closely around brain.
(iii) Arachnoid membrane. It is the middle membrane.
2. Cerebrospinal fluid is present in between the meninges. It protects brain from mechanical shock.
3. Bony structures, skull protects the brain and vertebral column protects the spinal cord.
Q. 12. (a) What are the functions of spinal cord ?
(b) Name the organ responsible for reflex action.
Ans. (a) Functions of spinal cord.
1. It acts as a modulator.
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2. It controls all the reflex actions.
3. It reduces the burden of brain.
(b) Spinal cord.
Q. 13. Give reasons for the following:
Injury to medulla oblongata results in sudden death.
Ans. As the centres of blood circulation and respiration lie in medulla oblongata, injury to it (medulla oblongata) results in sudden death.
Q. 14. Briefly explain the autonomic nervous system.
Ans. Autonomic nervous system. The autonomic nervous system coordinates the activities of viscera through the regulation of their smooth muscles and glands by its nerves.
The sympathetic nervous system prepares the body to face an emergency by accelerating heart beat and breathing rate; dilating the bronchioles to facilitate gas exchange; and sending blood to the organs which need it most such as heart, brain and skeletal muscle for “fight or flight”. It releases neurotransmitters adrenaline and noradrenaline into the synapses (adrenergic).
The parasympathetic nervous system acts when body is relaxing after an emergency. It restores heart beat and respiratory rate to normal and restarts digestion. It releases acetylcholine into the synapses (cholinergic).
Q. 15. Differentiate between medullated and non-medullated Nerve fibres.
Ans. Differences Between Medullated and Non-medullated Nerve Fibers
| Medullated (Myelinated) Nerve Fibres | Non-medullated (Non-myelinated) Nerve |
| 1. Medullary sheath is present. | 1. Medullary sheath is absent. |
| 2. They appear white in fresh state. | 2. They appear grey in fresh state. |
| 3. Nodes of Ranvier are present at intervals. | 3. Nodes of Ranvier are absent. |
| 4. Collateral nerve fibres are present. | 4. Collateral nerve fibres are absent. |
| 5. They are generally present in the white matter of brain and spinal cord and in cranial and spinal nerves. | 5. They are present in autonomic nerves. |
| 6. They carry impulses faster than non-medullated nerve fibres. | 6. They carry impulses slower than medullated nerve fibres. |
Q. 16. Write two functions of cerebellum ?
Ans. 1. Maintain equilibrium and posture.
2. Coordinates voluntary movements of muscles.
VERY SHORT ANSWER TYPE QUESTIONS
Q. 1. Why do buffaloes chew the cud?
Ans. It is a type of movement in response to food present in the oral cavity. It helps to break up tough food.
Q. 2. What happens when bright light is focussed on eyes ?
Ans. Eyes get closed in response to light so as to protect the eyes.
Q. 3. Where are receptors located in the body ?
Ans. Sense organs.
Q. 4. What is the function of gustatory receptors ?
Ans. To taste the food.
Q. 5. Name the organs concerned with sense of smell.
Ans. Olfactoreceptor.
Q. 6. Name the structural and functional unit of nervous system.
Ans. Neuron.
Q. 7. What is the function of dendrites ?
Ans. Dendrites acquire the information.
Q. 8. Name the structure of neuron which conduct impulse.
Ans. Axon.
Q. 9. Name the sites where electrical impulses are conducted into chemical impulses.
Ans. Synapse.
Q. 10. Mention the receptors for light and sound in animals.
Ans. Receptors for light. Photoreceptors (Eyes)
Receptors for sound. Phonoreceptors (Ears).
Q. 11. Can you taste a food when you are having severe cold?
Ans. No.
Q. 12. What is reflex action ?
Ans. Reflex action. It is sudden spontaneous, mechanical, involuntary response to a stimulus by voluntary organs.
Q. 13. Give two examples of reflex action.
Ans. (i) Closing of eyes in response to bright light.
(ii) Withdrawal of hand in case you touch a hot plate.
Q. 14. Which organ is involved in reflex action ?
Ans. Spinal cord.
Q. 15. What is the simplest kind of nerve pathway ?
Ans. Reflex arc.
Q. 16. Name three parts of neurons in complex reflex arc.
Ans. A complex reflex arc is composed of afferent, connector and efferent neurons.
Q. 17. What is a neuron?
Ans. Neuron. It is a structural and functional unit of nervous system. It is the largest cell of body. It has three components i.e. (i) cell body (ii) dendrites (iii) axon.
Q. 18. Name the largest cell present in human body.
Ans. Neuron.
Q. 19. What are the three basic regions of the brain ?
Ans. Fore brain, Mid brain, Hind brain.
Q. 20. Which part of the brain controls the heart?
Ans. Medulla oblongata.
Q. 21. Name the following:
(i) Structural and functional units of the nervous system.
(ii) Two type of peripheral nerves.
(iii) Most important part of the nervous system.
(iv) Three divisions of human brain.
(v) Largest part of the brain.
(vi) Two types of matter present in brain and spinal cord.
Ans. (i) Neurons
(ii) Cranial and spinal nerves
(iii ) Brain
(iv) Fore brain, mid and hind brain
(v) Cerebrum
(vi) White matter and grey matter.
ADDITIONAL IMPORTANT QUESTIONS
LONG ANSWER TYPE QUESTIONS
Q. 1. Explain briefly movements in plants.
Ans. Movements. Movements of plant parts can mostly be classified as growth movements and turgor movements. The growth movements are autonomic. The movements induced by external stimuli are called paratonic. Tropic movements can be of various types depending on the nature of external stimulus e.g., geotropism, thigmotropism, thermotropism, hydrotropism, chemotropism and phototropism.
Nastic movements are in bifacial organ. Seismonastic movements are observed in Mimosa pudica.
Q. 2. Explain the various movements in plants due to growth.
Ans. Growth movement in plants. They are autonomic. They are called tropic movements. They are always directional in relation to direction of stimulus. Mostly growth movements occur in cylindrical organs such as shoot tip root tip etc. Growth related movements are always slow.
Following are types of growth movements depending upon stimulus :
1. Phototropism. Stem and aerial parts of plants move/bend towards light. In this case, light is stimulus.
2. Geotropism. Growth movements induced by stimulus of force of gravity. Roots are underground and move towards the force of gravity. Stem and aerial parts move away from force of gravity.
Q. 3. What are growth regulators ?
Ans. Growth regulators. Growth is regulated not only by environmental factors like light and temperature but also by certain chemical substances within the plants. These substances are known as plant hormones, growth hormones, phytohormones or growth regulators. A plant hormone can be defined as a chemical substance, which is capable of translocation and regulating one or more physiological reactions, when present in low concentrations.
1. Auxins
2. Gibberellins
3. Cytokinins
4. Ethylene.
5. Abscisic acid (ABA).
On the basis of their effect, phytohormones can be divided into two groups:
(a) Growth promotors: These stimulate the plant growth e.g., auxins, gibberellins, cytokinins and ethylene.
(b) Growth inhibitors: These inhibit or retard plant growth e.g. ABA.
Q. 4. What are the functions of IAA?
Or
Explain role of auxin in plant growth.
Ans. Functions of IAA
1. IAA brings about cell elongation.
2. It initiates the formation and growth of roots and stem if applied to the cutting of stem.
3. Application of auxins causes formation of seedless fruits.
4. It has an inhibitory effect on abscission of leaves and fruits, which lead to leaf fall and fruit drop.
5. The parthenocarpy can be induced by application of auxins.
6. Respiration rate increases with auxins.
Q. 5. What are the physiological effects of gibberellins ?
Ans. Physiological effects of gibberellins are:
1. Gibberellins promote cell-division.
2. Gibberellins promote cell-elongation.
3. Gibberellins lead to increase in the length of internodes.
4. Gibberellins induce parthenocarpy in many cases e.g. tomato.
5. Gibberellins promote flowering in some plants like Chrysanthemum.
6. Gibberellins prevent senescence in leaves.
Q. 6. What are the functions of cytokinins ?
Ans. Functions of cytokinins
1. It promotes cell division by activating DNA synthesis.
2. It promotes the growth of lateral buds by neutralising the auxin.
3. It is reported that cytokinin activates protein synthesis in buds by incorporation of labelled amino acid.
4. It is also found to be effective in removing the apical dominance.
Q. 7. Write short notes on abscisic acid and ethylene.
Or
Write functions of abscisic acid.
Ans. Abscisic acid (ABA)
1. Abscisic acid (ABA) is a growth regulator found widespread in plants. It is a growth inhibitor.
2. Abscisic acid causes the inhibition of mitosis in the vascular cambium.
3. As the winter approaches, the ABA brings about the dormancy of axillary buds.
4. Abscisic acid also induces the dormancy in seeds.
5. It causes ageing in leaves.
ABA acts as a “stress hormone” helping the plant to cope with adverse environmental conditions.
Ethylene
Ethylene is synthesized in the plants from amino acid methionine. Ethylene produces the effect on the growth of vegetative and reproductive parts of the plant.
Ethylene is the only gaseous phytohormone. It is basically a growth inhibitor and brings about the following functions in the plant body.
1. Ethylene inhibits root growth and development of lateral buds.
2. Ethylene inhibits the elongation of stem and stimulates its transverse expansion.
3. The changes which occur during the ripening of fruit are also attributed to the effect of ethylene.
4. Ethylene also accelerates the process of ageing in plant organs.
Q. 8. Write a paragraph on turgor movements.
Or
Mechanism of movements shown by Mimosa pudica, if touched.
Ans. Turgor movements. It is a type of movement which is brought about in response to external stimulus of touch. Leaf of Mimosa pudica is a compound leaf. It gives a very quick response to a shock stimulus. Movements occur at a point away from point of touch. The plants use electrical-chemical means to convey the information. Plant cells change the shape by changing the amount of water in them resulting in swelling or shrinking therefore change occurs.
Q. 9. How do phototropism differ from geotropism ?
Ans. Differences between phototropism and geotropism
| Phototropism | Geotropism |
| 1. Response of parts of plants in the form of growth movement to the stimulus of light is called phototropism. | 1. It applies to growth movements induced by stimulus of force of gravity. |
| 2. Stem and aerial parts bend towards light source. | 2. Stem and aerial parts move away from force of gravity. |
| 3. Roots and other underground parts move away from source of light. | 3. Roots and other underground parts move towards to force of gravity. |
SHORT ANSWER TYPE QUESTIONS
Q. 1. How is control and co-ordination brought about in organisms ?
Ans. Control and Co-ordination in the body is of two types i.e. nervous control and UUEDA hormonal control. Nervous control is rapid. It takes place through electrical signals called nerve impulses. The hormonal control is through chemical messengers called hormones secreted by endocrine (ductless) glands and carried by blood to the target organs.
Q. 2. Write short note on movements in plants.
Ans. The movements of a plant or its part in direction of stimulus is known as tropism. Curvature movements in flowering plants are of two types: growth movements and turgor movements.
Growth movements are caused due to differential or unequal growth of an organ. They are slow and can be observed through time-lapse photography.
Some growth movements are autonomic i.e. self-controlled e.g. nutations. Others are paratonic i.e., induced by the external stimuli such as light, gravity, water or contact, etc. Paratonic movements are further of two types: tropic movements and nastic movements.
Turgor movements occur due to the differences in the turgidity or water potential of the groups of cells in different parts of the plant.
Q. 3. Differentiate tropic tropic and nastic movements.
Ans. Differences between tropic and nastic movements
| Tropic movement | Nastic movement |
| 1. It is always directional in relation to direction of stimulus. | 1. It is non-directional and is not related to the direction of movement. |
| 2. Mostly it occurs in cylindrical organs e.g. shoot tip. | 2. Such a movement is generally found in flat or asymmetrical organs e.g. leaves. |
| 3. It is a growth movement. | 3. It can be a growth or turgor movement. |
| 4. Action of movement is slow. | 4. Action of Movement is immediate. |
| 5. Reason for action is change in turgor. | 5. Reason for action is cell division. |
Q. 4. What do you understand by phototropism ?
Or
Explain the cause of shoot of plants bending towards light.
Or
How does phototropism occur in plant ?
Ans. Phototropism. It has been known from many years that plants bend toward light when they are exposed to it from one side of the long axis (i.e. unilateral light exposure). In general, stem and other aerial parts of the plants bend towards the light source (i.e. they are positively phototropic), while roots and other underground organs bend away from the light source (i.e., they are negatively phototropic).
Q. 5. Write a note on geotropism.
Ans. Geotropism. The term geotropism is applied to growth movements induced by stimulus of gravity.
Growth of an organ towards the centre of the earth is termed positive geotropism (e.g., main roots are positively geotropic), and growth away from the centre of earth is termed as negative geotropism (e.g., main stems are negatively geotropic). When the axis of an organ grows at right angle to the direction of gravity it is said to be diageotropic (e.g., rhizomes of certain grasses or stolons of potato).
Q. 6. List any four uses of auxins.
Ans. (i) Auxins are used to prevent premature fruit drop when applied close to the time of harvest.
(ii) Auxins induce initiation of roots in stem cuttings.
(iii) Auxins induce development of parthenocarpic fruits.
(iv) Many auxins (2, 4-D) are used as potent herbicides.
Q. 7. Explain the Nastic movements in plants.
Ans. Nastic movement
1. It is non-directional and is not related to the direction of movement.
2. Such a movement is generally found in flat or asymmetrical organs e.g. leaves.
3. It can be a growth or turgor movement.
VERY SHORT ANSWER TYPE QUESTIONS
Q. 1. What is the response of plants to light ?
Ans. Plants bend towards light.
Q. 2. Name any two types of tropism.
Ans. Types of tropism.
1. Phototropism 2. Geotropism.
Q. 3. Which part of the plant shows positive geotropism and why?
Ans. The main roots of plants show positive geotropism due to differential growth caused by unequal distribution of auxins.
Q. 4. Name the type of reversible movements occurring in living organisms.
Ans. Turgor movements.
Q. 5. What are turgor movements ?
Ans. Turgor movements. The turgor movements are based on the turgor pressure of the cells. These movements are caused by reversible changes in the cell size. Thus volume changes in the cells result in movements.
Q. 6. What is the effect of light on seedling?
Ans. Light is essential for proper growth and in proper light seedlings remain stout and green. Generally seedlings growing in dark become etiolated.
Q. 7. Define hydrotropism and chemo-tropism.
Ans. Hydrotropism. It is the movement of plant organs in response to unilateral stimulus of water. Chemotropism. It is the response of plants towards chemicals.
Q. 8. Name the plant hormone that inhibits the growth of plants.
Ans. Abscisic acid.
Q. 9. Which factors regulate growth and movements in plants ?
Ans. (i) External factors
(ii) Internal factors.
Q. 10. In which two groups of movements, auxin is believed to play a vital role?
Ans. Geotropism and phototropism.
Q. 11. What is meant by the term tropism ? Give examples.
Ans. These are plant growth responses to different stimuli governed by auxins. Response to touch (thigmotropism), gravity (geotropism) and light (phototropism) are examples.
Q. 12. How does chemical co-ordination take place in plants ?
Ans. Chemical co-ordination in plants takes place by plant growth regulators also called phytohormones.
Q. 13. List any four plant hormones.
Ans. (i) Auxins (ii) Cytokinins (iii) Gibberellins (iv) Abscisic acid.
Q. 14. Write one function each of auxins and cytokinins.
Ans. Function of auxin. Cell elongation;
Function of cytokinins. Cell division.
Q. 15. Expand IAA and ABA.
Ans. IAA. Indole acetic acid
ABA. Abscisic acid.
Q. 16. Name the plant hormone that exhibit growth.
Ans. ABA (Abscisic acid)
Q. 17. Why do leaves drop off seasonally ?
Ans. The leaves drop off seasonally as they stop producing auxins, which normally prevent formation of abscission zone which cuts off nutrients and water supply to leaves.
ADDITIONAL IMPORTANT QUESTIONS
LONG ANSWER TYPE QUESTIONS
Q. 1. Write secretions and functions of thyroid parathyroid, adrenal gland and pancreas.
Ans. The table given ahead indicates the endocrine glands, secretions and functions:
| Gland | Position | Hormone | Functions of the Hormone |
| Pituitary gland | Below the brain | Growth hormone | Promotes body growth by synthesis and deposition of proteins in the tissues, promotes growth of bones and muscles. |
| Thyroid gland | In the neck | Thyroxine | Controls protein, carbohydrate and fat metabolism, increases the metabolic rate, increases physical and mental growth of the body, maintains the basal metabolic rate in the body. |
| Pancreas | Below the stomach. | Insulin | Reduces amount of blood glucose, increases the use of glucose in the tissues and storage of glucose as glycogen in the liver and muscles. |
| Adrenal glands | On the top of each kidney | Adrenaline | Stress hormone. Helps us face stress. Increases blood flow to the skeletal muscles, increases blood sugar and respiration rate, increases heart beat and body temperature, dilates the blood vessels so that more blood flows to the muscles. Increases energy output in the body. |
| Testes | In scrotum of the male | Testosterone | Stimulates sperm production, Helps in development of male sex organs-prostate, penis etc, Development of male sex characters-beards, low pitch voice. |
| Ovaries | In abdomen of females | Estrogen | Helps in development of female sex organs-uterus, tubes and mammary glands. Developments of female sex characters-high pitch voice, body hairs. |
Q. 2. Give an account of any seven diseases caused by the excess and lesser secretions of various endocrine glands.
Ans.
| Diseases | Causes | Symptoms/Characteristics |
| 1. Gigantism | Over production of growth promoting hormone in childhood. |
Growth of bones at the joints. Abnormal height ranging from six and a half feet upwards.
|
| 2. Acromegaly | Over production of growth promoting hormone in adult. | Development of coarse skin, large nose, thick lips, huge hands and feet. |
| 3. Dwarfism | Deficiency of growth promoting hormone in children. | Stunted growth, retarded sexual development. |
| 4. Diabetes insipidus | Deficiency of antidiuretic hormone (ADH). |
Large quantities of dilute urine are produced. It is accompained by a desire to drink large quantities of water.
|
| 5. Goitre | Absence of iodine in the diet. | Enlargement of thyroid gland. |
| 6. Exophthalmic goitre | Over-secretion of thyroxine, weight, accelerated heart beat, etc. | Big swelling in the neck region and the bulging of eyes, loss of weight, accelerated heart beat, etc. |
| 7. Diabetes mellitus | Deficiency of Insulin. | Excretion of sugar in the urine. |
SHORT ANSWER TYPE QUESTIONS
Q. 1. What is gland ? Name the two types of glands.
Ans. Definition. A cell, a tissue or an organ which secretes certain useful chemical compounds required for particular function is called a gland.
Types. Animals have two types of glands: exocrine and endocrine.
Q. 2. Differentiate between exocrine gland and endocrine gland.
Ans. Differences between endocrine glands and exocrine glands
| Endocrine glands | Exocrine glands |
| 1. Endocrine glands have no ducts. (Ductless glands) | 1. They have ducts (Digestive glands). |
| 2. They secrete chemical substances called hormones. | 2. They secrete proteinaceous substances called enzymes. |
| 3. These glands bring about the chemical co-ordination of the body. | 3. These glands, by their secretion, hasten the biochemical reactions of the body. |
Q. 3. What are hormones? Why are they called chemical messengers ?
Ans. Hormones. They are informational molecules secreted by the endocrine cells in one part of the body in response to changes in external or internal environment, and carried by blood to another part where they stimulate or inhibit specific physiological processes for the good of the body as a whole.
In other words, the hormones are chemical messengers that regulate the biological processes in the organisms as they carry the information in the form of chemicals.
Q. 4. Nervous and hormonal system together perform the function of control and coordination in human beings. Justify the statement.
Ans. Nervous and hormone system. Both nerves and hormones transmit information between different parts in the animal body, in the same manner (chemical communication). Both coordinate and regulate physiological activities of the organisms. Moreover, there is a considerable coordination between the two. Synthesis and release of some hormones are regulated by nerves. On the other hand, hormones may also influence the activation of nerves. Because of their interrelationship, the nervous and the endocrine system are now together referred to as the neuroendocrine system.
Q. 5. What are the general functions of ‘hormones’ ?
Ans. Functions of Hormones.
1. Hormones stimulate the tissue activity
2. Hormones regulate growth and reproduction.
3. Hormones control metabolism.
4. Hormones synthesize, store and utilize substances like glucose.
5. Hormones conserve water and minerals.
Q. 6. What are the general properties of hormones ?
Ans. General properties of hormones :
1. The hormones themselves do not create biochemical processes. They only modify the existing metabolic processes and change the rate of action.
2. Hormonal actions are usually long lasting than those produced by nerve impulses.
3. They are effective in minute quantities.
4. They are secreted in response to specific stimuli.
5. They are secreted independent of one another.
Q. 7. Differentiate between hormones and enzymes.
Ans. Differences between hormones and enzymes
| Hormones | Enzymes |
| 1. They are produced by glands which lack ducts (Endocrines). | 1. They are generally produced by glands which bear the ducts. |
| 2. They may be steroids, amines or protein in chemical nature. | 2. They are always proteinic in nature. |
| 3. They are consumed during metabolism. | 3. They act as catalysts and are produced in the same quantity at the end of reaction. |
Q. 8. Name and locate six endocrine glands.
Ans. Endocrine glands of human body
1. Pituitary gland. Bottom of the diencephalon.
2. Thyroid. Front of neck.
3. Parathyroid. Two on each lobe of thyroid.
4. Adrenals. One on top of each kidney.
5. Pancreas. Behind and below the stomach.
6. Gonads. Ovaries in the abdomen of female and testes in scrotum of the male.
Q. 9. List some of the functions of hormones of pituitary gland.
Ans. Functions of hormones of pituitary gland
1. Regulates growth.
2. Influences the thyroid gland, the adrenals and gonads.
3. Can produce changes in the skin colour of many amphibians and fishes.
4. Regulates amount of water and salts in the body.
5. Influences migration and nest building in birds.
Q. 10. Name the hormones secreted by thyroid, parathyroid and pancreas.
Ans. Thyroid – Thyroxine
Parathyroid – Calcitonin and Parathormone
Pancreas – Insulin and Glucagon.
Q. 11. Name various hormones produced by anterior lobe of pituitary gland (at least four hormones and their functions.
Ans.
| Name | Functions | |
| Pituitary (Anterior lobe) |
(i) Growth hormone (GH)
(ii) Thyroid stimulating hormone (TSH)
(iii) Adrenocorticotrophic hormone (ACTH)
(iv) Follicle stimulating hormone (FSH)
(v) Luteinizing hormone
(vi) Luteotrophic hormone (LTH)
|
Controls growth of somatic cells, Promotes protein synthesis.
Regulates the growth of thyroid gland and secretion of thyroxine.
Controls secretion of adrenal cortex.
Controls spermatogenesis in male and stimulates growth of Graffin follicles in ovary of female.
Stimulates interstitial cells of testes to secrete testosterone, influences growth of male accessory sex organs.
Initiates milk secretion and stimulates corpus luteum of ovary to secrete progesterone.
|
Q. 12. What are the functions of oxytocin ?
Ans. Oxytocin causes the contraction of smooth muscles of uterus and thus takes part in parturition and expulsion of foetus and placenta. It also plays a role in lactation and causes ejection of milk from mammary glands. It stimulates the release of milk secreting factors from the adenohypophysis. The action of oxytocin is inhibited by the progesterone hormone of the ovary during the period of pregnancy.
Q. 13. Write a short note on the endocrine functions of corpus luteum of ovary.
Ans. Corpus luteum secretes two hormones namely 1. Relaxin and 2. Progesterone.
Relaxin helps in the relaxation of pelvic ligaments and the muscles to facilitate the child birth.
Progesterone is secreted after ovulation and is stopped before the next menstrual cycle. It prepares the uterus for pregnancy. It is also responsible for the implantation of the embryo in the uterus and for the development of placenta. It is also concerned with changes occurring in the preparation for and during pregnancy. It inhibits the contraction of uterus during the period of pregnancy.
Q. 14. List the functions of testosterone and estrogen.
Ans. Functions of testosterone. Develops male reproductive organs and secondary sexual characters.
Functions of estrogen. Develops female genital organs and secondary sexual characters.
Q. 15. Name the hormones which stimulate the testis.
Ans. 1. Follicular Stimulating Hormone (FSH). It stimulates the production in the testis. of sperms
2. Interstitial Stimulating Hormone (ICSH). It stimulates the interstitial cells of the testis and produce a male sex hormone known as ‘testosterone’.
The FSH and ICSH are secreted by pituitary gland.
Q. 16. List some of the functions of adrenal glands.
Ans. Functions of adrenal glands
1. Prepare the body for emergencies.
2. Regulate the kidney in maintaining salt and water balance.
3. Control blood pressure and pulse rate.
4. Control concentration of sodium, potassium and sugar in the body.
5. Control some sexual characteristics.
6. Influence breakdown of tissue proteins into amino acids.
Q. 17. Give the names of the hormones and the related glands concerning the following diseases :
(a) Goitre
(b) Myxoedema
(c) Cretinism
(d) Diabetes
(e) Addison’ disease
(f) Tetany.
Ans.
| Name of disease | Deficiency of Hormone | Name of gland |
|
(a) Goitre
(b) Myxoedema
(c) Cretinism
(d) Diabetes
(e) Addison’ disease
(f) Tetany
|
Thyroxine
Thyroxine
Thyroxine
Insulin
Glucocorticoids
Parathormone
|
Thyroid
Thyroid
Thyroid
Pancreas
Adrenal gland
Parathyroid gland
|
VERY SHORT ANSWER TYPE QUESTIONS
Q. 1. Name the following:
(i) Two types of glands present in our body.
(ii) The types of glands that secrete hormones.
(iii) The gland which functions both as exocrine and endocrine gland.
(iv) The other name of hormones.
(v) The gland which is called ‘Master gland’.
(vi) The two hormones secreted by posterior lobe of pituitary.
(vii) The name of gonadotropic hormones.
(viii) The expansion of STH and ACTH.
Ans. (i) Exocrine glands and endocrine glands
(ii) Endocrine glands or ductless glands
(iii) Pancreas
(iv) Chemical coordinators (messengers)
(v) Pituitary gland
(vi) Oxytocin and Vasopressin or ADH
(vii) Follicular Simulating Hormone (FSH), Luteinising Hormone (LH) and Luteotropic Hormone (LTH)
(viii) STH = Somatotropic Hormone, ACTH = Adreno corticotropic Hormone.
Q. 2. Name the following:
(i) The hormone of the pituitary gland which controls the activity of thyroid.
(ii) The hormone of the pituitary gland which controls the activity of adrenal gland.
(iii) The part of the pituitary gland which controls growth and development of gonads.
(iv) The hormone that promotes the growth in our body.
(v) The disease caused by the deficiency of STH (growth hormone) in children.
(vi) The disease caused by the oversecretion of STH (growth hormone) in children.
Ans. (i) Thyroid Stimulating Hormone (TSH)
(ii) Adreno Corticotropic Hormone (ACTH)
(iii) Anterior lobe (Adenohypophysis)
(iv) Growth hormone (Somatotropic Hormone) (STH).
(v) Dwarfism
(vi) Gigantism.
Q. 3. Name the following:
(i) Any one symptom of acromegaly.
(ii) The hormone associated with lactation in mammals.
(iii) The hormone which controls the water exchange in the renal tubules.
(iv) The hormone secreted by thyroid gland.
(v) The disease caused by the deficiency of iodine.
(vi) The diseases caused by the malfunctioning of thyroid gland.
Ans. (i) Long bones of limbs and jaws
(ii) Luteotropic hormone
(iii) Antidiuretic Hormone (ADH)
(iv) Thyroxine
(v) Cretinism
(vi) Cretinism and myxoedema.
Q. 4. Answer the following:
(i) The hormone secreted by parathyroid gland.
(ii) The cause of tetany.
(iii) The endocrine part of pancreas.
(iv) The two types of cells seen in Islets of Langerhans.
(v) The hormones that control blood glucose level.
Ans. (i) Parathormone
(ii) Deficiency of Parathormone
(iii) Islets of Langerhans
(iv) Alpha cells and Beta cells
(v) Insulin and glucagon.
Q. 5. Name the following:
(i) The cause of diabetes mellitus.
(ii) The two portions of adrenal gland.
(iii) The gland which function actively in emergency situations.
(iv) The hormone of pituitary that helps in child birth.
(v) The endocrine gland located on the top of kidneys.
(vi) The gland which secretes insulin.
Ans. (i) Deficiency of insulin
(ii) Adrenal cortex and adrenal medulla
(iii) Adrenal medulla
(iv) Oxytocin
(v) Adrenal gland
(vi) Pancreas.
Q. 6. Name the following:
(i) The hormone which prepares the body to meet any emergency situation.
(ii) An example of the disease caused due to insufficient secretion of hormone.
(iii) The gland, which produces the so called ’emergency hormone’.
(iv) Carrier of hormones from the gland to target organ.
(v) The hormone which controls (i.e. reduces) the level of sugar in blood and the gland which secretes it.
Ans. (i) Adrenaline
(ii) Cretinism
(iii) Adrenal
(iv) Blood
(v) Insulin, Pancreas.
Q. 7. What is the main element of thyroxine hormone ?
Ans. Iodine.
Q. 8. What is the main function of the vasopressin hormone ?
Ans. Regulate water contents in the blood.
Q. 9. Write the function of hormone ‘thyroxine’ in our body.
Ans. It regulates metabolism of carbohydrates, fats and proteins.
Q. 10. Which two systems of body work together for control and coordination of body parts?
Ans. Nervous system and Hormonal system (endocrine glands).
Q. 11. Which organ secretes a hormone when the blood sugar rises. Name a digestive enzyme released by this organ.
Ans. (i) Pancreas releases insulin hormone.
(ii) Trypsin enzyme.
Q. 12. Define endocrine glands.
Ans. These glands are ductless glands which secrete chemical messengers called hormones carried by blood, to target organs.
MULTIPLE CHOICE QUESTIONS
Select the correct answer out of the four alternatives :
1. The movement of shoot towards light is :
(A) geotropism
(B) hydrotropism
(C) chemotropism
(D) phototropism.
Ans. (D) phototropism.
2. The main function of abscisic acid in plants is to :
(A) increase the length of cells
(B) promote cell division
(C) inhibit growth
(D) promote growth of stem.
Ans. (C) inhibit growth
3. Which of the following is not associated with growth of plant ?
(A) Auxin
(B) Gibberellins
(C) Cytokinins
(D) Abscisic acid.
Ans. (D) Abscisic acid.
4. Iodine is necessary for the synthesis of which hormone ?
(A) Adrenaline
(B) Thyroxin
(C) Auxin
(D) Insulin.
Ans. (B) Thyroxin
5. Choose the incorrect statement about inuslin :
(A) It is produced from pancreas
(B) It regulates growth and development of the body
(C) It regulates blood sugar level
(D) Insufficient secretion of insulin will cause diabetes.
Ans. (B) It regulates growth and development of the body
6. The growth of tendril in pea plants is due to :
(A) effect of light
(B) effect of gravity
(C) rapid cell divisions in tendrillar cells that are away from the support
(D) rapid cells divisions in tendrillar cells in contact with the support.
Ans. (C) rapid cell divisions in tendrillar cells that are away from the support
7. The movement of sunflower in accordance with the path of sun is due to :
(A) phototropism
(B) geotropism
(C) chemotropism
(D) hydrotropism.
Ans. (A) phototropism
8. Which statement is not true about thyroxin ?
(A) Iron is essential for the synthesis of thyroxin
(B) It regulates carbohydrates, protein and fat metabolism in the body
(C) Thyroid gland requires iodine to synthesise thyroxin
(D) Thyroxin is also called thyroid hormone.
Ans. (A) Iron is essential for the synthesis of thyroxin
9. Dwarfism results due to :
(A) Excess secretion of thyroxin
(B) Less secretion of growth hormone
(C) Less secretion of adrenaline
(D) Excess secretion of growth hormone.
Ans. (B) Less secretion of growth hormone
10. Dramatic changes of body features associated with puberty are mainly because of secretion of:
(A) oestrogen from testes and testosterone from ovary
(B) estrogen from adrenal gland and testosterone from pituitary gland
(C) testosterone from testes and estrogen from ovary
(D) testosterone from thyroid gland and estrogen from pituitary gland.
Ans. (C) testosterone from testes and estrogen from ovary
11. Which of the following is a plant hormone ?
(A) Insulin
(B) Thyroxine
(C) Oestrogen
(D) Cytokinin.
Ans. (D) Cytokinin.
12. Posture and equilibrium of body is maintained by :
(A) Cerebrum
(B) Cerebellum
(C) Medulla oblongata
(D) All of above.
Ans. (B) Cerebellum
13. Cell division in plants is promoted by:
(A) Auxins
(B) Gibberellins
(C) Cytokinins
(D) None of these.
Ans. (C) Cytokinins
14. Sense of hearing, smell and sight are received from various receptors in :
(A) Fore brain
(B) Mid brain
(C) Hind brain
(D) All of these.
Ans. (A) Fore brain
15. Hormone secreted directly into blood and carried to different parts of the body is :
(A) Thyroxine
(B) Adrenaline
(C) Insulin
(D) None of these.
Ans. (B) Adrenaline
16. The hormone responsible for wilting of leaves is:
(A) Auxins
(B) Gibberellins
(C) Cytokinins
(D) Abscisic acid.
Ans. (B) Gibberellins
17. Iodine is required for the synthesis of :
(A) Oestrogen
(B) Thyroxin
(C) Adrenaline
(D) Insulin.
Ans. (B) Thyroxin
18. Which of the following is not an endocrine gland ?
(A) Pituitary
(B) Thyroid
(C) Adrenal
(D) Salivary.
Ans. (D) Salivary.
19. The sense of smell is the function of:
(A) Cerebrum
(B) Alfactory bulb
(C) Cerebellum
(D) Medulla Oblongata.
Ans. (D) Medulla Oblongata.
20. Insulin is secreted in:
(A) Pitutary gland
(B) Adrenal gland
(C) Pancreas
(D) Thyroid gland.
Ans. (C) Pancreas
21. Thyroxine is produced by:
(A) Pancreas
(B) Adrenal glands
(C) Adrenal
(D) Thyroid gland.
Ans. (D) Thyroid gland.
22. Which of the following inhibits growth in plants?
(A) Auxins
(B) Gibberellins
(C) Abscisic acid
(D) Cytokinins.
Ans. (C) Abscisic acid
23. The function of cerebellum is to :
(A) Cause movements of the body
(B) Maintain posture of body
(C) Keep balance of the body
(D) Maintain both balance and posture of the body.
Ans. (D) Maintain both balance and posture of the body.
24. The function of insulin is to:
(A) Regulate growth of the body
(B) Maintain sugar balance of the body
(C) Control production of thyroxine
(D) Remove harmful products from the body.
Ans. (B) Maintain sugar balance of the body
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