Control and Coordination: Class 10 Important Questions with Answers

Case-based questions (4 marks each)

(i) Name the type of action of pulling the hand back. (1) (ii) Where is this action decided? (1) (iii) Write the path of the impulse in this action, and explain why she felt the pain only a moment later. (2)

(i) Name this response. (1) (ii) Which hormone is responsible and where is it made? (1) (iii) Explain how this hormone causes bending and why only new growth changes direction. (2)

(i) Which hormone is acting and which gland makes it? (1) (ii) Why does her heart beat faster? (1) (iii) Why does she lose appetite? How does this hormone reach the heart? (2)

(i) Name the disease with swollen necks and the hormone involved. (1) (ii) Why does iodised salt help? (1) (iii) Name the hormone and gland responsible for the child's condition and the condition itself. What is the role of the hypothalamus here? (2)

20 MCQs (1 mark each)

1. Gustatory receptors detect
   (a) smell (b) taste (c) light (d) sound
2. The part of a neuron where information is acquired:
   (a) axon (b) dendrite (c) nerve ending (d) synapse
3. An electrical impulse is converted to a chemical signal at the
   (a) dendrite (b) cell body (c) axon end (d) nucleus
4. Reflex arcs are formed in the
   (a) brain (b) spinal cord (c) heart (d) muscles
5. Which is a voluntary action?
   (a) heartbeat (b) sneezing (c) writing (d) salivation
6. Vomiting and salivation are controlled by the
   (a) cerebrum (b) cerebellum (c) medulla (d) pituitary
7. Riding a bicycle needs the
   (a) medulla (b) cerebellum (c) hypothalamus (d) pons
8. The hunger centre is in the
   (a) fore-brain (b) mid-brain (c) medulla (d) spinal cord
9. CNS consists of
   (a) brain + spinal cord (b) cranial + spinal nerves (c) brain only (d) nerves only
10. Touch-me-not leaves fold due to
    (a) growth (b) auxin (c) change in water content of cells (d) muscle proteins
11. Roots growing towards water show
    (a) phototropism (b) hydrotropism (c) chemotropism (d) geotropism
12. Pollen tube growing towards the ovule is
    (a) phototropism (b) geotropism (c) chemotropism (d) thigmotropism
13. Hormone that inhibits growth:
    (a) auxin (b) gibberellin (c) cytokinin (d) abscisic acid
14. Cytokinins are found more in
    (a) roots (b) fruits and seeds (c) old leaves (d) bark
15. Adrenaline is secreted by the
    (a) thyroid (b) pituitary (c) adrenal glands (d) pancreas
16. Goitre is caused by deficiency of
    (a) iron (b) iodine (c) calcium (d) sodium
17. Insulin is produced by the
    (a) liver (b) pancreas (c) adrenal (d) thyroid
18. Deficiency of growth hormone in childhood causes
    (a) goitre (b) diabetes (c) dwarfism (d) gigantism
19. Hormones are carried by
    (a) nerves (b) blood (c) lymph only (d) muscles
20. Releasing hormones are secreted by the
    (a) hypothalamus (b) pituitary (c) thymus (d) pineal

Answer key

Assertion–Reason (10)

(a) Both A and R true, R explains A · (b) Both true, R does not explain A · (c) A true, R false · (d) A false, R true

1. A: Reflex actions are faster than voluntary actions. R: Reflex actions are decided in the spinal cord without thinking. → (a)
2. A: The brain is protected by the vertebral column. R: The brain sits in a fluid-filled balloon inside a bony box. → (d)
3. A: Plants respond to stimuli. R: Plants have a nervous system. → (c)
4. A: Shoots bend towards light. R: Auxin collects on the shady side and makes cells there grow longer. → (a)
5. A: Roots show positive geotropism. R: Roots grow away from light. → (b)
6. A: Hormonal control is slower than nervous control. R: Hormones travel through blood. → (a)
7. A: Iodised salt prevents goitre. R: Iodine is needed to make insulin. → (c)
8. A: During an emergency, blood flow to skin and gut decreases. R: Adrenaline diverts blood to skeletal muscles. → (a)
9. A: Abscisic acid promotes growth. R: Abscisic acid causes wilting of leaves. → (d)
10. A: A cell cannot send electrical impulses continuously. R: After an impulse a cell needs time to reset. → (a)

Give reasons (2 marks each)

1. Food tastes less when we have a cold.

Blocked nose → olfactory receptors cannot detect smell; flavour depends on both taste and smell. 2

2. Most multicellular organisms use chemical (hormonal) communication besides nerves.

Nerve impulses reach only connected cells and cannot be sent continuously; hormones reach all cells steadily and persistently. 2

3. The old parts of a shoot do not change direction when a plant is turned.

Phototropism is a growth movement; only growing regions (near the tip) respond, old grown parts cannot. 2

4. Diabetic patients are given insulin injections.

Their pancreas makes too little insulin, so blood sugar rises; insulin lowers it. 2

5. A person with a spinal cord injury may not feel pain in the legs.

Sensory impulses from the legs cannot travel through the damaged spinal cord to the brain. 2