NCERT Solutions Class 10 Science Chapter 6 – Control and Coordination
NCERT Solutions for Class 10 Science Chapter 6: Control and Coordination
This chapter explains how organisms respond to stimuli through the nervous system and hormonal coordination. It covers reflex actions, the human brain, endocrine system, and plant hormones. Expect 5-7 marks from this chapter.
In-text Questions and Answers
Page 119 Questions
Q1. What is the difference between a reflex action and walking?
Answer:
| Reflex Action | Walking |
|---|---|
| Involuntary, automatic response | Voluntary, conscious action |
| Controlled by spinal cord | Controlled by brain (cerebellum) |
| Very fast response | Comparatively slower |
| No thinking involved | Involves conscious thinking initially, becomes learned |
| Example: Pulling hand from hot object | Example: Walking to school |
Q2. What happens at the synapse between two neurons?
Answer: At the synapse:
- The nerve impulse reaches the axon terminal of the presynaptic neuron
- Synaptic vesicles release neurotransmitters (like acetylcholine) into the synaptic cleft
- Neurotransmitters bind to receptors on the postsynaptic neuron’s dendrite
- This generates a new electrical impulse in the next neuron
- Enzymes break down the neurotransmitters after transmission
Page 122 Questions
Q1. Which part of the brain maintains posture and equilibrium of the body?
Answer: The cerebellum (hindbrain) maintains posture, balance, and equilibrium of the body. It also coordinates voluntary muscular activities like walking, running, and cycling.
Q2. How do we detect the smell of agarbatti (incense stick)?
Answer:
- The volatile compounds from agarbatti diffuse through the air
- They reach the nose and stimulate olfactory receptors in the nasal cavity
- Receptors generate nerve impulses that travel via the olfactory nerve
- Impulses reach the olfactory area in the cerebrum (forebrain)
- The brain interprets these signals as the smell of agarbatti
Exercise Questions
Q1. Which of the following is a plant hormone? (a) Insulin (b) Thyroxin (c) Oestrogen (d) Cytokinin
Answer: (d) Cytokinin
Explanation: Cytokinin is a plant hormone that promotes cell division. Insulin, thyroxin, and oestrogen are animal hormones.
Q2. The gap between two neurons is called a:
(a) dendrite (b) synapse (c) axon (d) impulse
Answer: (b) synapse
Explanation: Synapse is the junction between two neurons where nerve impulses are transmitted through chemical neurotransmitters.
Human Endocrine Glands
| Gland | Hormone | Function |
|---|---|---|
| Pituitary | Growth hormone | Controls growth of body |
| Thyroid | Thyroxine | Regulates metabolism |
| Pancreas | Insulin | Regulates blood sugar |
| Adrenal | Adrenaline | Fight or flight response |
| Testes | Testosterone | Male secondary characters |
| Ovaries | Estrogen | Female secondary characters |
Key Takeaways
- Nervous system provides quick, point-to-point electrochemical coordination
- Reflex arc: Receptor → Sensory neuron → Spinal cord → Motor neuron → Effector
- Brain has three parts: Forebrain (thinking), Midbrain, Hindbrain (balance)
- Endocrine system provides slow, widespread chemical coordination via hormones
- Plants respond to stimuli through tropic movements and hormones (auxins, gibberellins)
- Feedback mechanisms regulate hormone levels in the body
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