1. Why is Pituitary called the "Master Gland"? It secretes
hormones that control other endocrine glands (e.g., TSH controls thyroid, FSH/LH control gonads). It
regulates growth, metabolism, and reproduction indirectly.
2. Why do we pull our hand away from fire before feeling
pain? Reflex action. The spinal cord triggers motor response (withdrawing hand) immediately,
while the pain signal still travels to the brain. This protects us faster than conscious thought.
3. How is brain protected? (a) Skull (cranium) provides hard
outer protection. (b) Meninges (3 membranes) cushion it. (c) Cerebrospinal fluid (CSF) acts as a shock
absorber.
4. Why is the use of iodized salt advised? Iodine is
essential for synthesis of Thyroxine (thyroid hormone). Deficiency causes Goitre (enlarged thyroid) and in
children, Cretinism (stunted growth, mental retardation).
5. How does the body maintain blood sugar level? Feedback
mechanism involving pancreas. High glucose → Pancreas releases Insulin → Glucose stored as glycogen. Low
glucose → Pancreas releases Glucagon → Glycogen converted to glucose.
6. What is the role of Hypothalamus? It monitors blood
hormone levels. If thyroxine is low, it signals pituitary to release TSH, which stimulates thyroid to
produce more thyroxine. This is negative feedback.
7. Why can't diabetics rely on feedback alone? Their
pancreas either doesn't produce enough insulin (Type 1) or cells don't respond to it (Type 2). External
insulin injections are needed to regulate blood glucose.
8. What happens if spinal cord is damaged? Signals between
brain and body below the injury are blocked. This can cause paralysis (loss of movement) and loss of
sensation below the injury level.
9. Why can't spinal cord injuries be easily repaired?
Neurons in the central nervous system (brain, spinal cord) have very limited ability to regenerate. Once
damaged, connections are permanently lost.
10. Can reflex actions still occur after spinal injury? If
the reflex arc (below injury) is intact, reflexes can still occur even without brain involvement. Example:
Knee-jerk reflex may persist even in paralyzed patients.
11. Assertion: Plants do not have nervous system but still
respond to stimuli.
Reason: Coordination in plants is achieved by plant hormones (phytohormones) which cause
growth movements (tropisms) and nastic movements.
Both A and R are True, R is correct explanation of A.
12. Why do alcoholics often have poor coordination? Alcohol
affects the cerebellum, which controls balance and coordination. Damage or impairment leads to lack of motor
control, slurred speech, and difficulty walking.
