Control & Coordination CBQs — CBSE Class 10 (2027) with step-wise solutions

Sample Control & Coordination CBQs

1. Question 1MCQ1 mark
   Sapna suffers from a condition due to which her average blood sugar level is 174 mg/dL. The average blood sugar level in a healthy adult is <140 mg/dL. Which of the following could be the cause of Sapna's condition?
   • insufficient production of thyroxine in her body
   • insufficient production of insulin in her body
   • excess production of thyroxine in her body
   • excess production of insulin in her body
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   1. [1 mark] Correct option: (2) insufficient production of insulin in her body. Insulin lowers blood glucose; too little of it leaves the blood sugar persistently high, which is what her reading shows. Excess insulin would lower it, and thyroxine regulates metabolism rather than blood glucose directly.

   Answer: insufficient production of insulin in her body

2. Question 2Assertion-Reason1 mark
   Assertion (A): The folding of the leaves of a touch-me-not (chhui-mui) plant when a child touches them is a tropic movement. Reason (R): The cells of the leaves change their shape by changing the amount of water in them.
   • (A) Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
   • (B) Both Assertion and Reason are true but Reason is NOT the correct explanation of Assertion.
   • (C) Assertion is true but Reason is false.
   • (D) Assertion is false but Reason is true.
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   1. [1 mark] (D) — The folding is not a tropic (directional growth) movement; it is a quick movement in response to touch involving no growth, so A is false. R is true: the leaf cells change shape by changing the amount of water in them, which causes the folding.

   Answer: (D) Assertion is false but Reason is true.

3. Question 3Short answer2 marks
   (a) As first line of defense, stress hormones are released in humans. As an equivalent, which hormone is most likely to be released as first line of defense in plants? (b) There have been reports of plant hormones being found in animal bodies even when they are not synthesised by the animal. What can be the most common pathway of entry of such hormones in animals?
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   1. [1 mark] (a) Abscisic acid/ ABA
   2. [1 mark] (b) through food

   Answer: (a) abscisic acid (ABA); (b) through food

4. Question 4Case study4 marks
   Arjun was helping in the kitchen of his home in Chennai. Without noticing, he touched the hot lid of a pressure cooker and pulled his hand away almost instantly. Only a moment later did he feel the burning pain. His elder sister, a nursing student, explained that the heat was detected by nerve endings in his skin. The message travelled along a nerve to the spinal cord, where it was passed on to another nerve that carried the instruction to the muscles of his arm. At the same time, the information also travelled up to the brain. (i) Name the receptor organ and the effector in this action. (ii) Where are the connections between the input nerve and the output nerve made in this action? (iii) Explain why Arjun pulled his hand away before he felt the pain, and state one advantage of this kind of response.
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   1. [1 mark] (i) Receptor organ — skin (heat-sensitive nerve endings in the skin); effector — muscles of the arm.
   2. [1 mark] (ii) In the spinal cord — the sensory (input) nerve meets the motor (output) nerve through a relay neuron in the spinal cord; this pathway is the reflex arc.
   3. [1 mark] (iii) The response is a reflex action: the reflex arc in the spinal cord sends the instruction to the muscles directly without involving the thinking part of the brain, which is slower; the feeling of pain arises only when the information, sent up the spinal cord, reaches the brain a moment later.
   4. [1 mark] (iii) Advantage: the reflex gives a very quick response, so the hand is withdrawn before serious burning — it protects the body from injury.

   Answer: (i) Skin; arm muscles; (ii) spinal cord; (iii) reflex arc bypasses the thinking brain — quick response that prevents injury.

5. Question 5Long answer5 marks
   Rohan is batting in the final of an inter-school cricket tournament in Kolkata. As the bowler runs in, Rohan feels nervous and his heart starts beating faster. He watches the ball, decides to play a shot, and swings his bat while keeping his balance on his feet. (a) Name the part of the brain that is the thinking part and takes the decision to play the shot, and the part that maintains his posture and balance. (b) Trace the path of the message from his eyes to the muscles of his arms. (c) How do the muscle cells of his arm bring about movement on receiving the message? (d) Name the hormone that makes his heart beat faster when he is nervous, and the gland that secretes it. (e) State two ways in which the hormonal control seen in (d) differs from the nervous control seen in (b).
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   1. [1 mark] (a) Fore-brain (cerebrum is also accepted) — the main thinking part of the brain, which takes the decision; cerebellum — maintains posture and balance of the body.
   2. [1 mark] (b) Receptors in the eyes (photoreceptors) detect the ball → sensory neurons carry the impulse to the brain (fore-brain) → the decision is sent through motor neurons (via the spinal cord) → the muscles of the arms (effectors).
   3. [1 mark] (c) Muscle cells contain special proteins that change both their shape and their arrangement in the cell in response to the nervous electrical impulse; this gives the muscle cells a shorter form, so the muscle contracts and the arm moves.
   4. [1 mark] (d) Adrenaline; secreted by the adrenal glands.
   5. [1 mark] (e) Any two: hormonal signals (chemical) travel through the blood and reach all cells of the body, whereas electrical impulses reach only cells connected by nervous tissue; nervous control is very quick, whereas hormonal action is slower.

   Answer: (a) Fore-brain; cerebellum. (b) Eye receptors → sensory neurons → brain → motor neurons → arm muscles. (c) Muscle proteins change shape/arrangement → cells shorten. (d) Adrenaline, adrenal glands. (e) Blood-borne, reaches all cells, slower vs electrical, nerve-connected cells only, fast.

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