Class 10 Science · Chapter 6

Control and Coordination

286 Class 10 Science questions on Control and Coordination from the NCERT textbook, NCERT Exemplar and CBSE board papers 2018–2026, each with its answer and a step-by-step solution.

CBSE Class 10 Science previous year papers, with answers →

Questions · page 13 of 15

1. Q241 CBSE 2023
   In animals ​the control and coordination is provided by nervous and muscular tissues. Nervous tissue is made of an organized network of nerve cells or neurons. In human beings, thinking is a complex activity which involves more complex ​mechanisms and neural connections. These are concentrated in the brain which is the main coordinating centre of ​the human body. The brain and spinal ​cord constitute the Central Nervous System which ​receives information from all ​parts of the body ​and integrates it.

   1. (a)How is the brain protected from shocks and injuries ?[1]
   2. (b)Write the main functions of (i) sensory neuron and (ii) motor neuron in a reflex arc.[1]
   3. (c)(i)Which part of the brain is involved in activities like (i) picking a pencil and (ii) vomiting ? State whether these actions are voluntary or involuntary.[2]
   4. (c)(ii)OR : How does the central nervous system communicate with other parts of the body to carry out various activities ? Name two components of this system.[2]
   Show answer

   Skull and meninges protect the brain; sensory neurons carry impulses in, motor neurons out; cerebellum (pencil), medulla (vomiting); peripheral nerves link the CNS.

   (a) The brain is enclosed in a bony box, the cranium (skull). Inside this box it lies in a fluid-filled balloon - three membranes called the meninges with cerebrospinal fluid between them - and this fluid acts as a shock absorber, so the brain is protected from shocks and injuries. (b) (i) The sensory neuron carries the impulse from the receptor to the spinal cord, that is into the central nervous system. (ii) The motor neuron carries the impulse from the spinal cord out to the effector - the muscle or gland - which carries out the response. (c)(i) (i) Picking a pencil - the **cerebellum** (part of the hind-brain), which gives precision to voluntary movements and maintains posture and balance; this action is **voluntary**. (ii) Vomiting - the **medulla** (in the hind-brain), which controls involuntary actions; this action is **involuntary**. OR (c)(ii) The central nervous system communicates with the other parts of the body through the **peripheral nervous system**. Sensory nerve fibres bring information from the receptors into the brain and the spinal cord, and motor nerve fibres carry the instructions out from them to the effectors, the muscles and glands. Two components of this system: the **cranial nerves** (arising from the brain) and the **spinal nerves** (arising from the spinal cord). (The central nervous system itself is made up of the brain and the spinal cord.)

   Step-by-step solution →
2. Q242 CBSE 2020
   Answer question numbers 4(a) to 4(d) on the basis of your understanding ​of the following information ​and related studied concepts. Thyroid gland is a bilobed structure situated in our neck region. It secretes a hormone called thyroxine. Iodine is necessary for the thyroid gland to make thyroxine. Thyroxine regulates carbohydrate, protein and fat metabolism in the body. It promotes growth of body ​tissues also. When there is an excess of thyroxine ​in the body, a person suffers from hyperthyroidism and ​if this gland is ​underactive ​it results in hypothyroidism. Hyperthyroidism is diagnosed by blood tests that measure the ​levels of thyroxine and Thyroid Stimulating Hormone (TSH). Hypothyroidism is caused due to the deficiency of iodine in our diet resulting in a disease called goitre. Iodised salt can be included in our diet to control it.

   1. (a)Where is thyroid gland situated in our body ?[1]
   2. (b)State the function of thyroxine in human body.[1]
   3. (c)What is hyperthyroidism ?[1]
   4. (d)How can we control hypothyroidism ?[1]
   Show answer

   The thyroid is in the neck; thyroxine regulates metabolism and growth; hyperthyroidism is excess thyroxine; iodised salt controls hypothyroidism.

   (a) In the neck region; the thyroid is a bilobed gland in the neck. (b) Thyroxine regulates carbohydrate, protein and fat metabolism in the body, and it promotes the growth of body tissues. (c) Hyperthyroidism is the condition caused by an excess of thyroxine in the body, when the thyroid gland is overactive. (d) By including iodised salt in the diet, which supplies the iodine the thyroid gland needs to make thyroxine. Other relevant measures, such as eating food rich in iodine, also earn credit.

   Step-by-step solution →
3. Q243 CBSE 2020
   Questions numbers 4(a) to 4(d) are based on table given below. Study the table in which the ​levels of Thyroid Stimulating Hormone (TSH) in women are given and answer ​the questions that follow on the basis of ​understanding of the following paragraph and the related studied concepts. Women are at greater risk for developing abnormal ​TSH levels during menstruation, while giving birth and after going through menopause. Around ​5% of women in the ​United States have some kind of thyroid problem compared to 3% of men. Despite claims that high TSH increases your ​risk for heart disease, a 2013 study found no link between high TSH and heart diseases. But a 2017 study ​showed that older women are especially at risk for developing thyroid cancer if they have high TSH levels along with thyroid nodules.

   Age Range	Normal (mU/L)	Low (mU/L)
   18 – 29 years	0.4 – 2.34 mU/L	< 0.4 mU/L
   30 – 49 years	0.4 – 4.0 mU/L	< 0.4 mU/L
   50 – 79 years	0.46 – 4.68 mU/L	< 0.46 mU/L

   1. (a)A 35 year old woman has TSH level 6.03 mU/L. What change should she bring in her diet to control this level ?[1]
   2. (b)When do women face a greater risk of abnormal TSH level ?[1]
   3. (c)State the consequence of low TSH level.[1]
   4. (d)Name the mineral that is responsible for synthesis of hormone secreted by thyroid gland.[1]
   Show answer

   She should include iodine (iodised salt) in her diet; the risk is greater in menstruation, childbirth and menopause; low TSH means an overactive thyroid.

   (a) Her TSH, $6.03$ mU/L, is above the normal range for her age group ($0.4$ to $4.0$ mU/L for 30 to 49 years), which shows that her thyroid is making too little thyroxine; she should monitor her iodine intake and include enough iodine in her diet, for example by using iodised salt. (b) Any two: during menstruation, while giving birth (pregnancy) and after going through menopause. (c) A low TSH level is a sign that the thyroid gland is not working normally: usually the gland is overactive and releases too much thyroxine, and metabolism speeds up. Such a gland is often enlarged, which shows as a swelling of the neck region (goitre). (d) Iodine.

   Step-by-step solution →
4. Q244 CBSE 2020
   Question numbers 4(a) – 4(d) are based on the table and related ​information in the passage given below. Thyroid Stimulating Hormone (TSH) ​stimulates thyroid gland to produce thyroxine. Study the table given below. It is important to monitor TSH levels during ​pregnancy. High TSH levels and hypothyroidism can especially ​affect chances of miscarriage. Therefore, proper medication in consultation ​with a doctor is required to regulate/control the ​proper ​functioning of the ​thyroid gland.

   TSH levels during pregnancy

   Stage of pregnancy	Normal (mU/L)	Low (mU/L)	High (mU/L)
   First trimester	0.2 – 2.5	< 0.2	2.5 – 10
   Second trimester	0.3 – 3.0	< 0.3	3.01 – 4.5
   Third trimester	0.8 – 5.2	< 0.8	> 5.3

   1. (a)Give the full form of TSH.[1]
   2. (b)State the main function of TSH.[1]
   3. (c)Why do TSH levels in pregnant women need to be monitored ?[1]
   4. (d)A pregnant woman has TSH level of 8.95 mU/L. What care is needed for her ?[1]
   Show answer

   TSH (Thyroid Stimulating Hormone) makes the thyroid produce thyroxine; high TSH in pregnancy risks miscarriage, so medication and monitoring under a doctor are needed.

   (a) Thyroid Stimulating Hormone. (b) TSH, released by the pituitary gland, stimulates (regulates) the thyroid gland to produce the hormone thyroxine. (c) Because an abnormal TSH level, particularly a high TSH level with hypothyroidism, can increase the chances of miscarriage; monitoring detects it early so that it can be corrected. (d) Her TSH level is high: $8.95$ mU/L is above the normal range in every trimester. She needs proper medication in consultation with a doctor to regulate the functioning of her thyroid gland, with regular monitoring of her TSH level.

   Step-by-step solution →
5. Q245 CBSE 2020
   Reflex action is controlled by

   1. (a)nerves
   2. (b)brain
   3. (c)spinal cord
   4. (d)dendrite
   Show answer

   (c) spinal cord

   Step-by-step solution →
6. Q246 CBSE 2020
   For question numbers 13 and 14, two statements ​are given ​— one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (a), ​(b), (c) and ​(d) ​as given below ​:

   Assertion (A): Plant hormones are chemicals produced in plants which help to coordinate growth, development and response to stimulus and environment.

   Reason (R): Abscisic acid is a plant hormone that promotes cell division.

   1. (a)Both (A) and (R) are true and (R) is the correct explanation of the assertion (A).
   2. (b)Both (A) and (R) are true, but (R) is not the correct explanation of the assertion (A).
   3. (c)(A) is true, but (R) is false.
   4. (d)(A) is false, but (R) is true.
   Show answer

   (c) (A) is true, but (R) is false.

   Step-by-step solution →
7. Q247 CBSE 2020
   For question numbers ​13 and 14, two ​statements are given ​— one labelled as Assertion (A) and ​the ​other labelled as Reason (R). Select the correct answer to ​these questions from the codes (a), (b), (c) and (d) as given below :

   Assertion (A): The brain allows us to think and take actions based on that thinking.

   Reason (R): The hind brain is the main thinking part of the brain which has regions which receive sensory impulses from various receptors.

   1. (a)Both (A) and (R) are true and (R) is the correct explanation of the assertion (A).
   2. (b)Both (A) and (R) are true, but (R) is not the correct explanation of the assertion (A).
   3. (c)(A) is true, but (R) is false.
   4. (d)(A) is false, but (R) is true.
   Show answer

   (c) (A) is true, but (R) is false.

   Step-by-step solution →
8. Q248 CBSE 2020
   A cheetah, on ​seeing a prey, ​moves towards ​him at ​a very high speed. ​What causes the ​movement of his muscles ? How does the chemistry ​of cellular components of muscles change during this ​event ?
   Show answer

   Nerve impulses from the brain make muscle cells shorten; their special proteins change shape and arrangement, giving a shorter form so the muscles contract.

   Cause of the movement: on seeing the prey, nerve impulses are generated. The brain sends electrical impulses through the nerves to the muscles, and the muscle fibres move: the muscle cells change their shape so that they shorten. Change in the muscle cells: muscle cells have special proteins that change both their shape and their arrangement in the cell in response to the nervous electrical impulses. The new arrangement of these proteins gives the muscle cells a shorter form, so the muscles contract and the cheetah moves.

   Step-by-step solution →
9. Q249 CBSE 2020
   Write in tabular form the location and function of ​the hormones secreted by each ​of ​the ​following ​glands present in the human ​body :

   1. (a)Pituitary gland
   2. (b)​Thyroid gland
   3. (c)​Pancreas
   Show answer

   The pituitary (base of the brain) controls growth, the thyroid (neck) regulates metabolism and the pancreas (below the stomach) regulates blood sugar.

   (a) Pituitary gland: located at the base of the brain; its growth hormone regulates the growth and development of the body. (b) Thyroid gland: located in the neck; its hormone thyroxin regulates carbohydrate, protein and fat metabolism in the body. (c) Pancreas: located in the abdomen, just below the stomach; its hormone insulin regulates the blood sugar level.

   Step-by-step solution →
10. Q250 CBSE 2020
    A squirrel is in a ​scary ​situation. Its body has to ​prepare for ​either fighting or running away. State the immediate changes that take place in its body so ​that the squirrel is able to ​either ​fight or run?
    Show answer

    Adrenaline makes the heart beat faster, diverts blood to the skeletal muscles and raises the breathing rate, preparing the squirrel to fight or run.

    In the scary situation, the squirrel's adrenal glands secrete the hormone adrenaline directly into the blood. Adrenaline brings about these immediate changes: (1) The heart beats faster, supplying more oxygen to the muscles. (2) The blood supply to the digestive system and the skin is reduced, as the muscles around their small arteries contract, so more blood is diverted to the skeletal muscles. (3) The breathing rate increases because of contractions of the diaphragm and the rib muscles. Together these changes prepare the body to fight or to run.

    Step-by-step solution →
11. Q251 CBSE 2020
    Name the parts (a) to (e) in the ​following ​diagram. What is ​the ​term given to the ​sequence ​of events occurring ​in ​the diagram ?

    Show answer

    The parts are (a) receptor, (b) sensory neuron, (c) spinal cord, (d) relay neuron and (e) motor neuron; the sequence is a reflex arc.

    (a) Receptor (sense organ in the skin of the fingers); (b) Sensory neuron; (c) Spinal cord; (d) Relay neuron; (e) Motor neuron. The sequence of events shown is a reflex arc, the pathway of a reflex action.

    Step-by-step solution →
12. Q252 CBSE 2020
    Why is chemical communication better than ​electrical impulses as ​a means ​of communication between ​cells ​in ​a multi-cellular organism?
    Show answer

    Chemical signals carried by the blood reach every cell and need no reset time, unlike electrical impulses.

    Chemical communication is better for two reasons: (1) Electrical impulses reach only those cells that are connected by nervous tissue (neurons), whereas chemical signals such as hormones, carried by the blood, can reach each and every cell of the body. (2) After generating and transmitting an electrical impulse, a cell needs time to reset its mechanism before it can generate a new impulse, whereas no such time is needed in chemical communication.

    Step-by-step solution →
13. Q253 CBSE 2020
    1. (a)What ​is tropism ​?
    2. (b)How ​do auxins promote the growth of a tendril ​around ​a support?
    Show answer

    Tropism is directional growth movement in response to a stimulus; auxin makes the tendril's far side grow faster, so it coils around the support.

    (a) Tropism is the directional movement of a plant part, brought about by growth, in response to a stimulus; the movement is either towards the stimulus or away from it, as when a shoot bends towards light. (b) When the tip of a tendril touches a support, more auxin diffuses from the tip towards the side of the tendril away from the support. Auxin makes cells grow longer, so that side grows faster than the side in contact with the support, and the tendril bends and coils around the support.

    Step-by-step solution →
14. Q254 CBSE 2020
    Define geotropism. ​Draw a labelled ​diagram ​of a ​plant ​showing geotropic ​movements of ​its parts.
    Show answer

    Geotropism is growth of a plant part in response to gravity; roots are positively geotropic and shoots negatively geotropic.

    Geotropism: the movement, by growth, of a part of a plant in response to gravity. Roots grow downwards, towards gravity, and are positively geotropic; shoots grow upwards, away from gravity, and are negatively geotropic. Diagram: a potted plant laid on its side, with the shoot bending upward (labelled negatively geotropic) and the roots bending downward (labelled positively geotropic), as in the figure.

    Step-by-step solution →
15. Q255 CBSE 2020
    What constitutes the ​central and ​peripheral ​nervous systems ? How are the components of central nervous ​system ​protected ? ​Which ​signals will get disrupted in case of a spinal cord injury ?
    Show answer

    CNS is brain and spinal cord, PNS is cranial and spinal nerves; the cranium and backbone protect; spinal injury disrupts sensory and motor signals.

    Central nervous system: the brain and the spinal cord. Peripheral nervous system: the nerves that connect the CNS with the rest of the body, that is, the cranial nerves arising from the brain and the spinal nerves arising from the spinal cord. Protection: the brain lies inside a bony box, the cranium (skull), and within it is contained in a fluid-filled balloon (membranes and fluid) that absorbs shocks; the spinal cord is enclosed and protected by the vertebral column (backbone). Spinal cord injury: the signals that have to pass through the injured part of the cord are disrupted in both directions: sensory signals from the receptors of the body below the injury to the brain (so feeling there is lost), motor signals from the brain to the muscles below the injury (so voluntary movement there is lost), and the reflex actions whose reflex arcs pass through the damaged part of the cord.

    Step-by-step solution →
16. Q256 CBSE 2020
    (a) Name the ​hormone secreted by

    1. (i)​Pituitary, ​and
    2. (ii)Thyroid stating one main function of each. Name the disorder a person is ​likely to suffer from due to the deficiency of the ​above mentioned hormones. (b) How ​is the timing and amount of hormone released regulated ​? Explain with an example.
    Show answer

    Pituitary: growth hormone (dwarfism); thyroid: thyroxin (goitre); hormone release is regulated by feedback, e.g. insulin rises and falls with blood sugar.

    (a) (i) The pituitary gland secretes growth hormone, which regulates the growth and development of the body (it stimulates growth in all organs). A deficiency of growth hormone in childhood causes dwarfism. (ii) The thyroid gland secretes thyroxin, which regulates carbohydrate, protein and fat metabolism in the body to provide the best balance for growth. Iodine is needed to make thyroxin, so when the diet lacks iodine, too little thyroxin is made and the person suffers from goitre, a swollen neck caused by an enlarged thyroid gland. (b) The timing and amount of hormone released are regulated by feedback mechanisms. Example: when the sugar level in the blood rises, it is detected by the cells of the pancreas, which respond by producing more insulin; as the blood sugar level falls, insulin secretion is reduced.

    Step-by-step solution →
17. Q257 CBSE 2020
    What ​are ​plant hormones ? Name four different types of ​plant hormones and state ​one ​function ​of ​each.
    Show answer

    Plant hormones are chemicals that coordinate growth and responses; auxin, gibberellins and cytokinins promote growth, while abscisic acid inhibits it.

    Plant hormones (phytohormones) are chemical compounds that help to coordinate growth, development and responses to the environment in plants; they are synthesised at places away from where they act and diffuse to the area of action. Auxin: helps the cells to grow longer (cell elongation), for example when a shoot bends towards light. Gibberellins: help in the growth of the stem. Cytokinins: promote cell division (they are plentiful in fruits and seeds). Abscisic acid: inhibits growth; its effects include wilting of leaves.

    Step-by-step solution →
18. Q258 CBSE 2020
    1. (a)Write the names ​of the hormones ​secreted by the pituitary gland and the ​adrenal gland. State ​the functions of ​these hormones in the human body.
    2. (b)Explain with ​the help of an example, the feedback mechanism for the ​regulation of hormonal secretion in the human body.
    Show answer

    Pituitary secretes growth hormone, adrenal secretes adrenaline; feedback adjusts hormone release, as insulin secretion rises with blood sugar and falls as it drops.

    (a) Pituitary gland: growth hormone. It regulates the growth and development of the body (its deficiency in childhood leads to dwarfism). Adrenal gland: adrenaline. It prepares the body to deal with an emergency: it increases the heart rate, so that more oxygen reaches the muscles, increases the breathing rate, and diverts blood from the digestive system and skin to the skeletal muscles. (b) The timing and amount of hormone released are regulated by feedback mechanisms: the effect of a hormone is sensed and its secretion is adjusted. Example: when the sugar level in the blood rises, it is detected by the cells of the pancreas, which respond by producing more insulin; insulin lowers the blood sugar, and as the level falls, insulin secretion is reduced.

    Step-by-step solution →
19. Q259 CBSE 2019
    How ​do ​auxins promote ​the growth of ​a tendril ​around ​a support ?
    Show answer

    Auxin collects on the side of the tendril away from the support, so that side grows faster and the tendril coils round the support.

    When a tendril comes in contact with a support, auxin (a plant hormone made at the growing tip) diffuses towards the side of the tendril away from the point of contact. Auxin makes the cells on that side grow longer, so the part of the tendril away from the support grows faster, while the part in contact with the support does not grow as rapidly. Because the two sides grow unequally, the tendril bends towards the support and coils round it, and so the plant clings to the support.

    Step-by-step solution →
20. Q260 CBSE 2019
    What is ​insulin ? ​Why are some ​patients ​of diabetes ​treated by giving injections ​of ​insulin ?
    Show answer

    Insulin is a pancreatic hormone that lowers blood glucose; it is injected when the pancreas does not make enough.

    Insulin is a hormone secreted by the pancreas. It regulates the amount of glucose (sugar) in the blood: when the blood sugar level rises, the pancreas releases more insulin, which lowers it. In some patients of diabetes the pancreas does not secrete enough insulin, so the sugar level in their blood stays high. Injections of insulin supply the missing hormone and reduce the blood glucose level to normal.

    Step-by-step solution →