CBSE Class 10 Science Control And Coordination Worksheet Set H

Multiple Choice Questions

Question. In a neuron conversion of electrical signal to a chemical signal occurs at :
(a) Cell body
(b) Dendritic end
(c) Axonal terminals
(d) Axon
Answer: (c)

Question. The growth of tendrils in pea plants is due to :
(a) Effect of gravity
(b) Effect of chemicals
(c) Rapid cell division in tendrillar cells that are away from the support
(d) Rapid cell division in tendrillar cells in contact with the support
Answer: (c)

Question. The shape of guard cells changes due to change in the :
(a) Protein composition of cells
(b) Temperature of cells
(c) Amount of water in cells
(d) Position of nucleus in cells
Answer: (c)

Question. The substance that triggers the fall of mature leaves and fruits from plants is due to :
(a) Auxin
(b) Gibberellin
(c) Abscisic acid
(d) Cytokinin
Answer: (c)

Question. Which of the following is a plant hormone ?
(a) Insulin
(b) Thyroxin
(c) Oestrogen
(d) Cytokinin
Answer: (d)

Question. The movement of root away from light is :
(a) Positive phototropism
(b) Negative hydrotropism
(c) Negative phototropism
(d) Positive geotropism
Answer: (c)

Question. Cretinism results due to :
(a) Excess secretion of growth hormone
(b) Under secretion of thyroxin
(c) Excess secretion of adrenaline
(d) Under secretion of growth hormone
Answer: (b)

Question. The gap between two neurons is called a :
(a) Dendrite
(b) Synapse
(c) Axon
(d) Impulse
Answer: (b)

Question. The brain is responsible for :
(a) Thinking
(b) Regulating the heart beat
(c) Balancing the body
(d) All of the above
Answer: (d)

Question. Involuntary actions in the body are controlled by :
(a) Medulla in fore brain
(b) Medulla in mid brain
(c) Medulla in hind brain
(d) Medulla in spinal cord
Answer: (c)

Question. Match the following
Column I | Column II
(a) Thyroxine | (i) Causes breasts to develop in females
(b) Adrenaline | (ii) Causes the male to start producing sperms
(c) Insulin | (iii) Prepares the body for an emergency
(d) Estrogen | (iv) Controls the metabolic rate
(e) Testosterone | (v) Regulaates the amount of sugar in blood
Answer: (a) (iv), (b) (iii), (c) (v), (d) (i), (e) (ii).

Fill in the blanks

Question. Fill in the blanks
(a) A neuron which carries an impulse to the brain is called a ............................... neuron.
(b) ............................... is the hormone that causes phototropism in plants.
(c) The response of leaves to the sunlight is called ............................... .
Answer: (a) Sensory, (b) Auxin, (c) Phototropism.

Very Short Answers Type Questions

Question. List two different functions performed by pancreas in our body. [2019 Delhi]
Answer: (a) Pancreas makes two hormones i.e., insulin and glycogen that regulates blood sugar level. (b) It secretes pancreatic juice that aids in the digestion of food.

Question. (a) Name one gustatory receptor and one olfactory receptor present in human beings.
(b) Write a and b in the given flow chart of neuron through which information travels as an electrical impulse.
Dendrite → a → b → End point of Neuron [2018]
Answer: (a) Gustatory receptor present in tongue to detect taste. Olfactory receptor present in nose to detect smell.
(b) a — Cyton/'cell body', b — Axon.

Question. Name the hormones secreted by the following endocrine glands and specify one function of each :
(a) Thyroid (b) Pituitary (c) Pancreas [2018]
Answer: (a) Thyroid gland :- Thyroxine hormone. Function: It regulates metabolism of carbohydrates, fats and proteins and is thus responsible for best balanced body growth.
(b) Pituitary gland :- Growth hormone. Function: It regulates growth and development of body. However, its reduced secretion causes dwarfism and excess secretion causes gigantism.
(c) Pancreas :- Insulin. Function: Insulin regulates the blood sugar level & brings back the blood sugar level to normal.

Question. Which part of the brain maintains posture and equilibrium of the body ? 
Answer: Cerebellum of the hind brain maintains posture and equilibrium of the body.

Question. Which signals will get disrupted in case of a spinal cord injury ? 
Answer: Spinal cord controls mainly the reflex actions. So reflex actions and involuntary actions will get disrupted.

Question. What do you mean by reflex action ?
Answer: Reflex action is an automatic, quick and involuntary action in the body brought about by a stimulus.

Question. What are parthenocarpic fruits ?
Answer: Fruits that are not produced by fertilisation process and are seedless are called parthenocarpic fruits.

Question. Give an example of plant hormone that promotes growth ?  
Answer: Auxin is a plant hormone that promotes growth.

Question. Why are the electrochemical signals not an efficient means of communication in plants ?
Answer: Plants do not have nervous system i.e., specialised tissues like neurons as in case of animals nor do they have endocrine system to carry electrochemical signals. So, it is not an efficient means of communication in plants.

Question. Why Mimosa pudica leaves dropped down when touched ?
Answer: Due to changes in turgour pressure when we touch the leaves of Mimosa pudica plant leaves dropped down. The stimulus of touch leads to loss of turgour at the base of leaflets and petioles leading to drooping down of leaves.

Question. Why are some patients of diabetes treated by giving injections of insulin ? 
Answer: Insulin is secreted by beta cells of Islets of Langerhans of pancreas. They convert excess glucose to glycogen stored in liver thus lowering glucose level in the blood. In diabetes patients, the sufficient amount of insulin is not secreted by pancreas so they have high sugar level in their blood. To control the sugar level they are treated by giving insulin injections.

Question. Pancreas and gonads perform dual functions. Give reasons to justify the statement.
Answer: Pancreas secretes hormones as well as various digestive enzymes i.e., they are associated with both digestive and endocrine system. Similarly, gonads produce male and female gametes along with male and female sex hormones i.e., they are associated with both reproductive and endocrine system. Hence, we can say pancreas and gonads perform dual functions.

Question. What will happen if a ripened fruit is kept in a basket of raw fruits ?
Answer: If a ripened fruit is kept in a basket of raw fruits it will help in ripening of other raw fruits as the ripened fruit contains ethylene hormone which is responsible for ripening of fruits.

Question. What is geotropism ? Draw a labelled diagram of a potted plant showing positive geotropism and negative geotropism.  
Answer: The upward growth of shoots and downward growth of roots in response to the pull of earth’s gravity is called geotropism. [Diagram: Potted plant placed horizontally with shoot bending upwards (negatively geotropic) and root bending downwards (positively geotropic).]

Short Answers Type Questions

Question. What are plant hormones ? Name the plant hormones responsible for the following :  
(a) Growth of stem
(b) Promotion of cell division
(c) Inhibition of growth
(d) Elongation of cells
Answer: In plants, growth, development and response to the environment are controlled and co-ordinated by a special class of chemical substances known as phytohormones. They are synthesised in minute amounts.
(a) Gibberellins (b) Cytokinins (c) Abscisic acid (d) Auxins

Question. What is feedback mechanism of hormonic regulation. Take the example of insulin to explain this phenomenon. 
Answer: It is the mechanism by which the amount of any chemical increases or decreases resulting in secretion of the related hormone control of many cell activities, so they are very important for homeostasis most hormones are regulated by feedback mechanisms. A feedback mechanism is a loop in which a product feeds back to control its own production. Most hormone feedback mechanism involves negative feedback loops. Negative feedback keeps the concentration of a hormone within a narrow range. For example, the control of blood sugar by insulin is an example of a negative feedback mechanism. When blood sugar rises, receptors in a body sense a change. In turn the control center secretes insulin into the blood effectively lowering the blood sugar level.

Question. Nervous and hormonal systems together perform the function of control and coordination in human beings, Justify this statement with the help of an example. 
Answer: The nervous system controls and coordinates all the functions in the body. It carries out its function in close coordination with hormonal system. Nerves don’t reach every hook and corner of body, hence needs assistance from hormones to control all the parts of body. Nervous control is faster. Hormonal control is slower. Hormonal control is based on feedback mechanism and tells body to pace up or slow down. Nervous control is on the other hand, a direct control.
Example : In situation of iodine deficiency hypothalamus releases hormones to stimulate pituitary gland it further sends stimulating hormone to thyroid gland to secrete thyroxine that regulates carbohydrate metabolism.

Question. Why does the flow of signals in a synapse from axonal end of one neuron to dendritic end of another neuron take place but not in the reverse direction? Explain.  
Answer: [Descriptive Answer based on Topper's transcript: The nerve impulses are transmitted from one neuron to the other in the form of electric impulses. At the axonal end, chemical neurotransmitters like acetylcholine are released which trigger an impulse in the dendrites of the next neuron. This chemical is only released at the axon terminal and receptors are only present on the dendrites, ensuring one-way flow.]

Question. What happens at the synapse between two neurons ? 
Answer: Synapse is a point of contact between the axon terminals of one neuron with the dendrite of another neuron. The terminals of axon are swollen which contains a chemical called acetylcholine which is a neurotransmitter, which induces impulses in the dendrites of next neuron. Synapse acts as one way valve which prevents the back flow of impulses from axon terminals. So, impulse moves from dendrites through cyton to axon. It allows the nerve impulses in one direction.

Question. What is the need for a system of control and coordination in an organism ? 
Answer: Multicellular organisms are highly complex. Every activity need to be regulated so that the activities can occur in proper time and correct sequence. Various organs and parts of the body should work together in a coordinate manner to perform a particular function. For proper control and coordination in higher organisms both nervous and endocrine system plays a major role. For example : While riding a bicycle there should be proper coordination between our hands and handle of our cycle.

Question. What is the role of brain in reflex action ?  
Answer: Reflex actions are mainly controlled by spinal cord. For quick response to the stimulus spinal cord is generally involved but the information also reaches the brain where the thinking process occurs. Brain does not play any role for quick response to reflex action. But some reflex actions are only controlled by brain called cerebral reflexes like salivation at the sight of tempted food.

Question. When our finger gets pricked by a sharp nail, we immediately take away our finger. Explain the pathway from stimulus to response ?
Answer: When our finger gets pricked by the sharp iron nail the finger receives the stimuli. It acts as a receptor organ. The sensory neuron carries the impulse from finger to the spinal cord [Central nervous system]. The spinal cord interpretes these impulses and generates motor impulse. These impulses are carried by motor neuron to the effector organ. By receiving the motor impulses immediately we take away our finger from the nail. This whole phenomenon is called reflex action and the path of impulse from Receptor → Sensory neuron → Spinal cord → Motor neuron → Effector is called reflex arc.

Question. Name the endocrine gland which secretes growth hormone. What will be the effect of the following on a person :
(a) Deficiency of growth hormone
(b) Excess secretion of growth hormone
Answer: Pituitary gland secretes growth hormone.
(a) Deficiency of growth hormone causes dwarfism.
(b) Excess secretion of growth hormone causes gigantism.

Question. Draw the structure of a neuron and explain its functions ? 
Answer: Neuron or nerve cell is the structural and functional unit of nervous system. The three parts of the neuron are cyto or cell body, dendrites and axon.
(a) Dendrites are fine, branched cytoplasmic projections of cyton which are the site of receiving information and they conduct these impulses to cyton.
(b) Cyton receives impulses from dendrites and passes through axon. Cyton contains nucleus, nissl’s granules and other cell organelles.
(c) Axon is a long process from cyton which is surrounded by an insulating sheath called myelin sheath. Axon conducts nerve impulses away from cyton. The terminals of axon are swollen which contains chemicals called neurotransmitters. This chemical sends a new impulse in the dendrites of adjacent neurons.

Question. The figure represents certain phenomenon pertaining to the nervous system.
(a) What does the figure represents ?
(b) Name the parts labelled a, b, c, d and e.
(c) Give the function of parts labeled a, b, d.
Answer: (a) The figure represents reflex arc.
(b) a – Receptor, b – Sensory neuron, c – Spinal cord, d – Motor neuron and e – Effector.
(c) Receptor is a group of cells or organ that receives the stimuli and converts it to an impulse. Sensory neuron carries the impulses from receptors to the central nervous system i.e., brain or spinal cord. Motor neuron carries impulses from central nervous system to the effector organs.

Question. What is the difference between the manner in which movement takes place in a sensitive plant and the movement in our legs ?
Answer:
1. Movement in sensitive plant occurs in response to external stimuli like touch; Movement in legs occurs voluntarily according to our will.
2. Movement in sensitive plant occurs due to change in turgour pressure in the cells of plant due to change in water content; Movement in legs is controlled by cerebellum of hind brain.
3. Movement in sensitive plant involves hormonal control; Movement in legs involves nervous control.
4. Movement in sensitive plant involves no such involvement of proteins; Movement in legs involves contraction and relaxation of muscles where muscle proteins are involved.

Question. What is the difference between a reflex action and walking ? 
Answer:
1. Reflex action is an involuntary action which is not under the control of our will; Walking is a voluntary action which is under the control of our will.
2. Spinal cord controls the reflex action; Cerebellum of hind brain controls walking.
3. Reflex action is spontaneous, automatic and quick; Walking is under conscious control and takes longer time.
4. Reflex action occurs suddenly and we do not have to learn it; Walking has to be learned as we grow up.

Question. During a street fight between two individuals, mention the effects on the following organs by the autonomic nervous system, in the table given below :
Organs | Sympathetic nervous system | Parasympathetic system
Answer:
Lungs | Dilates bronchi and bronchioles | Constricts bronchi and bronchiole
Heart | Increases heart rate | Decreases heart rate
Salivary gland | Inhibits saliva secretion | Stimulates saliva secretion
Pupil of eye | Dilation | Constriction

Question. Different parts of brain are associated with specific functions. Name the part of human brain which perform the following functions :  
(a) Sensation of feeling full
(b) Vomiting
(c) Picking up a pencil
(d) Riding a bicycle
Answer: (a) Forebrain (b) Medulla or Hind Brain (c) Cerebellum or Hind Brain (d) Cerebellum or Hind Brain

Long Answers Type Questions

Question. (a) Why is the use of iodised salt advisable ? Name the disease caused due to deficiency of iodine in our diet and state its one symptom.
(b) How do nerve impulses travel in the body ? Explain. 
Answer: (a) Iodised salt is advisable because iodine is necessary for the formation of thyroxine hormone by thyroid gland. Goitre is the disease caused due to its deficiency. Symptom : The neck of the person appears to be swollen due to the enlargement of thyroid gland.
(b) Two neurons are not joined to one another completely. There is a small gap between a pair of neuron. This gap is called synapse. The nerve impulse are carried out to this gap by the help of neuro transmitter (chemical substance). The conduction of nerve impulse through the synapse takes place in the form of electrical nerve impulse. When a stimulus acts on the receptor, an electrical impulse is produced with the help of chemical reaction. This electrical impulse passes through the synapse and then to the other neuron. Thus, in this way nerve impulses travel in the body.

Question. What is hydrotropism ? Design an experiment to demonstrate this phenomenon. 
Answer: The movement of root of plants towards water is called hydrotropism.
Take two glass troughs A and B fill each one of them two-thirds with soil. In trough A plant a tiny seedling. In trough B plant a similar seedling and also place a small ‘clay pot’ inside the soil. Water the soil in trough A daily and uniformly. Do not water the soil in trough B but put some water in the clay pot buried in the soil. Leave both the troughs for a few days. Now, dig up the seedlings carefully from both the trough without damaging their roots. We will find that the root of seedling in trough A is straight. On the other hand, the root of seedling in trough B is found to be bent to the right side (towards the clay pot containing water). This can be explained as follows: In trough A, the root of seedling gets water from both sides. In trough B, the roots gets water oozing out from the clay pot. The experiment shows that the root of a plant grows towards water. In other words, the root of a plant is positively hydrotropic.

Question. What are reflex actions ? GIve examples ? Explain reflex arc by an example with labelled diagram ?
Answer: Reflex action is a quick, automatic, involuntary, unconscious response in the body brough about by a stimulus. Examples: (a) Withdrawal of hand suddenly on touching a hot plate. (b) Withdrawal of finger suddenly when pricked by a thorn. (c) Shivering of the body on feeling cold. (d) Sudden closure of the eyelids when bright light falls on the eye. Reflex arc is the shortest route taken by impulse from receptor to effector. [Diagram: Receptor (finger) → Sensory neuron → Spinal cord (Relay neuron) → Motor neuron → Effector (muscles in hand).]

Question. What are the major parts of the brain ? Mention the function of different parts ?
Answer: (a) Forebrain : It comprises of cerebrum and diencephalon. (i) Cerebrum is the seat of intelligence, memory, will power, consciousness. It controls voluntary actions. (ii) Diencephalon consists of thalamus and hypothalamus. Hypothalamus controls body temperature and pituitary gland.
(b) Midbrain is a small tubular part which controls reflexes involving eyes and ears.
(c) Hindbrain comprises of cerebellum, pons, medulla oblongata. (i) Cerebellum controls and coordinates muscular activity and maintains posture and balance. (ii) Pons regulate rate of respiration. (iii) Medulla oblongata controls functioning of internal organs and involuntary actions like beating of heart, breathing, peristalsis.

Question. Name various plant hormones. Give their physiological effects on plant growth and development ?
Answer:
1. Auxins: Promotes cell growth, stem and fruit growth, regulates growth movements i.e., tropism, induces parthenocarpy.
2. Gibberellins: Promotes growth in stems and fruits, induces parthenocarpy, stimulates flowering, enhances germination.
3. Ethylene: Promotes growth and ripening of fruits, helps in breaking dormancy of seeds and buds.
4. Cytokinins: Promotes cell division, delay senescence of leaves, promotes opening of stomata, overcomes dormancy of seeds.
5. Abscisic acid: Promotes dormancy in seeds, inhibits growth, promotes senescence of leaves, promotes closing of stomata.

Question. Explain the difference between nastic movements and tropic movements in plants ?
Answer:
1. Tropic movements are directional; Nastic movements are non-directional.
2. Tropic movements include phototropism, geotropism, etc; Nastic movements include seismonastic and nyctinastic movements.
3. Tropic movement occurs towards or away from stimulus; Nastic movement is independent of stimulus direction.
4. Tropic response is slow and involves growth; Nastic response is quick and does not involve growth.

Question. How is the movement of leaves of the sensitive plant different from the movement of shoot towards light ? 
Answer:
1. Movement of sensitive plant is nastic; Shoot movement is tropic.
2. Sensitive plant movement does not involve growth and is fast; Shoot movement involves growth and is slow.
3. Sensitive plant movement is due to change in turgour pressure; Shoot movement is due to unequal distribution of auxin.
4. Sensitive plant movement occurs due to stimulus of touch; Shoot movement occurs due to stimulus of light.

Assertion and Reasoning Based Questions

Question. Assertion : In spite of not having nervous system, plants can sense things.
Reason : Plants can sense things with the help of hormones.
(a) If both assertion and reason are true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true, but reason is not the correct explanation of assertion.
(c) If assertion is true, but reason is false.
(d) If assertion is false but reason is true.
Answer: (a)

Question. Assertion : Synapse is a gap through which nerve impulse pass from one neuron to the next.
Reason : Neuron is the functional unit of nervous system.
(a) If both assertion and reason are true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true, but reason is not the correct explanation of assertion.
(c) If assertion is true, but reason is false.
(d) If assertion is false but reason is true.
Answer: (b)

Question. Assertion : It is advised to have iodized salt in our diet.
Reason : It prevents us from goitre.
(a) If both assertion and reason are true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true, but reason is not the correct explanation of assertion.
(c) If assertion is true, but reason is false.
(d) If assertion is false but reason is true.
Answer: (a)

Question. Assertion : Cerebrum controls the body posture.
Reason : Cerebrum is not connected to internal ear.
(a) If both assertion and reason are true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true, but reason is not the correct explanation of assertion.
(c) If assertion is true, but reason is false.
(d) If assertion is false but reason is true.
Answer: (d)

Question. Assertion : Cytokinins promote cell division in plants.
Reason : Full form of ABA is abscisic acid.
(a) If both assertion and reason are true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true, but reason is not the correct explanation of assertion.
(c) If assertion is true, but reason is false.
(d) If assertion is false but reason is true.
Answer: (b)

Creating Based Questions

Question. ‘Synapses act like one-way valves’ – Elaborate.
Answer: The chemical substance is present only on one side of the gap, so nerve impulse can go across only from one side ( which contains the chemical substance).

Question. Create a flow chart of neuron through which information travels as an electrical impulse by filling up ‘a’ and ‘b’.
Dendrite → a → b → end point of neuron.
Answer: (a) Cell body or cyton (b) Axon

Question. Using the following words below, construct a reflex arc. Sensory nerves, receptor, effector, stimulus, brain or spinal cord, response, motor neurons.
Answer: Stimulus → Receptor → Sensory nerves → Brain or spinal cord → Motor neurons → Effector → Response.

Question. Choose the incorrect word from the following and replace it with the correct word :
(a) Pancreas is called the master gland.
(b) Iron is needed for production of thyroxine.
Answer: (a) Pancreas is the incorrect word replaced by pituitary gland.
(b) Iron is the incorrect word replaced by iodine.

Question. ‘An alcoholic person usually walks clumsily’— develop a better explanation for this statement.
Answer: Cerebellum is the part of the brain that maintains balance and posture. After consumption of alcohol the cerebellum gets affected by the alcohol for which it cannot maintain balance and posture properly and hence walk clumsily.