Control and Coordination Part 3: MCQs (Q51–Q75)
📘 Control and Coordination – MCQs (Class 10 Science)
🔹 Part 3: Questions 51–75
Q51. Which gland secretes melatonin, the hormone that regulates sleep?
A) Thyroid
B) Pineal gland
C) Pituitary
D) Adrenal
Correct Answer: B) Pineal gland
Explanation:
- A) Thyroid → Secretes thyroxine.
- ✅ B) Pineal gland → Secretes melatonin, regulates sleep-wake cycle.
- C) Pituitary → Master gland, secretes growth hormone.
- D) Adrenal → Produces adrenaline.
Q52. The main function of synapse is to:
A) Produce neurotransmitters
B) Allow impulses to pass between two neurons
C) Insulate axons
D) Store energy
Correct Answer: B) Allow impulses to pass between two neurons
Explanation:
- A) Neurotransmitters are produced at axon terminals, not synapse itself.
- ✅ B) Synapse → Junction between neurons where impulse transmits chemically.
- C) Insulation → Myelin sheath.
- D) Storage → Not the function of synapse.
Q53. Which part of the nervous system controls voluntary actions?
A) Spinal cord
B) Medulla
C) Cerebrum
D) Cerebellum
Correct Answer: C) Cerebrum
Explanation:
- A) Spinal cord → Reflexes.
- B) Medulla → Involuntary actions.
- ✅ C) Cerebrum → Controls voluntary actions like writing, talking.
- D) Cerebellum → Maintains posture and balance.
Q54. Which plant hormone is responsible for fruit ripening?
A) Auxin
B) Ethylene
C) Gibberellin
D) Cytokinin
Correct Answer: B) Ethylene
Explanation:
- A) Auxin → Cell elongation.
- ✅ B) Ethylene → Gaseous hormone, accelerates fruit ripening.
- C) Gibberellin → Stem elongation.
- D) Cytokinin → Cell division.
Q55. Which of the following is an example of chemotropism?
A) Bending of root towards gravity
B) Growth of pollen tube towards ovule
C) Bending of stem towards light
D) Closure of stomata during water stress
Correct Answer: B) Growth of pollen tube towards ovule
Explanation:
- A) Gravity → Geotropism.
- ✅ B) Chemotropism → Growth guided by chemical signals.
- C) Light → Phototropism.
- D) ABA hormone closes stomata, not tropism.
Q56. Which hormone stimulates milk secretion in mothers?
A) Prolactin
B) Oxytocin
C) Estrogen
D) Progesterone
Correct Answer: A) Prolactin
Explanation:
- ✅ A) Prolactin → From pituitary, stimulates milk secretion.
- B) Oxytocin → Milk ejection and childbirth contractions.
- C) Estrogen → Female secondary characters.
- D) Progesterone → Maintains pregnancy.
Q57. Which part of the brain controls emotions and drives like hunger?
A) Cerebellum
B) Hypothalamus
C) Medulla
D) Pons
Correct Answer: B) Hypothalamus
Explanation:
- A) Cerebellum → Balance.
- ✅ B) Hypothalamus → Controls hunger, thirst, emotions, body temperature.
- C) Medulla → Involuntary activities.
- D) Pons → Relay of signals.
Q58. The peripheral nervous system consists of:
A) Brain and spinal cord
B) Cranial and spinal nerves
C) Only cranial nerves
D) Only spinal cord
Correct Answer: B) Cranial and spinal nerves
Explanation:
- A) Brain and spinal cord → CNS.
- ✅ B) PNS = Cranial nerves + Spinal nerves.
- C, D → Incomplete definitions.
Q59. Which hormone is called the stress hormone?
A) Insulin
B) Cortisol
C) Thyroxine
D) Estrogen
Correct Answer: B) Cortisol
Explanation:
- A) Insulin → Sugar regulation.
- ✅ B) Cortisol (adrenal gland) → Released during stress.
- C) Thyroxine → Metabolism.
- D) Estrogen → Female hormone.
Q60. Which part of the eye controls the amount of light entering?
A) Lens
B) Cornea
C) Retina
D) Iris
Correct Answer: D) Iris
Explanation:
- A) Lens → Focuses light.
- B) Cornea → Refraction.
- C) Retina → Image formation.
- ✅ D) Iris → Adjusts pupil size, controls light entry.
Q61. The hormone that promotes seed dormancy is:
A) Gibberellin
B) Auxin
C) Abscisic acid
D) Cytokinin
Correct Answer: C) Abscisic acid
Explanation:
- A) Gibberellin → Breaks dormancy.
- B) Auxin → Growth.
- ✅ C) Abscisic acid → Inhibits germination, induces dormancy.
- D) Cytokinin → Cell division.
Q62. Which part of the human brain controls involuntary actions like vomiting?
A) Cerebrum
B) Medulla
C) Cerebellum
D) Hypothalamus
Correct Answer: B) Medulla
Explanation:
- A) Cerebrum → Voluntary actions.
- ✅ B) Medulla → Involuntary activities like vomiting, heartbeat.
- C) Cerebellum → Balance.
- D) Hypothalamus → Emotions, hunger, thirst.
Q63. Which plant hormone delays ageing in leaves?
A) Auxin
B) Cytokinin
C) Ethylene
D) Abscisic acid
Correct Answer: B) Cytokinin
Explanation:
- A) Auxin → Growth.
- ✅ B) Cytokinin → Delays senescence, promotes cell division.
- C) Ethylene → Speeds ripening, ageing.
- D) ABA → Promotes wilting.
Q64. Which of the following is not an involuntary action?
A) Heartbeat
B) Blinking of eyes
C) Breathing
D) Writing
Correct Answer: D) Writing
Explanation:
- A) Heartbeat → Involuntary.
- B) Blinking → Reflex, involuntary.
- C) Breathing → Involuntary but can be controlled voluntarily to some extent.
- ✅ D) Writing → Voluntary action.
Q65. Which organ secretes digestive enzymes and hormones both?
A) Stomach
B) Pancreas
C) Liver
D) Intestine
Correct Answer: B) Pancreas
Explanation:
- A) Stomach → Secretes acid and enzymes only.
- ✅ B) Pancreas → Exocrine (enzymes) + Endocrine (insulin/glucagon).
- C) Liver → Produces bile, not enzymes.
- D) Intestine → Secretes enzymes, no hormones.
Q66. Which part of the neuron carries impulse to the cell body?
A) Axon
B) Dendrite
C) Myelin sheath
D) Synapse
Correct Answer: B) Dendrite
Explanation:
- A) Axon → Carries away from cell body.
- ✅ B) Dendrites → Receive impulse and carry to cell body.
- C) Myelin → Insulates axon.
- D) Synapse → Junction between neurons.
Q67. Which hormone is secreted by adrenal gland?
A) Insulin
B) Adrenaline
C) Thyroxine
D) Prolactin
Correct Answer: B) Adrenaline
Explanation:
- A) Insulin → Pancreas.
- ✅ B) Adrenaline → “Fight or flight” hormone from adrenal gland.
- C) Thyroxine → Thyroid.
- D) Prolactin → Pituitary.
Q68. What is the structural and functional unit of the nervous system?
A) Brain
B) Neuron
C) Spinal cord
D) Nerve
Correct Answer: B) Neuron
Explanation:
- A) Brain → Made of neurons.
- ✅ B) Neuron → Functional unit transmitting impulses.
- C) Spinal cord → Part of CNS.
- D) Nerve → Bundle of neurons.
Q69. Which hormone is responsible for phototropism in plants?
A) Auxin
B) Cytokinin
C) Gibberellin
D) Ethylene
Correct Answer: A) Auxin
Explanation:
- ✅ A) Auxin → Uneven distribution causes bending towards light.
- B, C, D → Not responsible for phototropism.
Q70. Which part of the human brain coordinates muscular movements?
A) Medulla
B) Cerebellum
C) Cerebrum
D) Pons
Correct Answer: B) Cerebellum
Explanation:
- A) Medulla → Involuntary functions.
- ✅ B) Cerebellum → Coordinates muscular movements, balance.
- C) Cerebrum → Intelligence, memory.
- D) Pons → Relay.
Q71. Which hormone increases heart rate and blood pressure in emergency?
A) Insulin
B) Adrenaline
C) Thyroxine
D) Estrogen
Correct Answer: B) Adrenaline
Explanation:
- A) Insulin → Controls sugar.
- ✅ B) Adrenaline → Emergency hormone, increases heart rate and BP.
- C) Thyroxine → Metabolism.
- D) Estrogen → Female hormone.
Q72. Which part of the brain controls body temperature?
A) Medulla
B) Cerebrum
C) Hypothalamus
D) Cerebellum
Correct Answer: C) Hypothalamus
Explanation:
- A) Medulla → Involuntary actions.
- B) Cerebrum → Intelligence, memory.
- ✅ C) Hypothalamus → Maintains temperature (thermoregulation).
- D) Cerebellum → Balance.
Q73. The hormone responsible for wilting and falling of leaves is:
A) Cytokinin
B) Auxin
C) Gibberellin
D) Abscisic acid
Correct Answer: D) Abscisic acid
Explanation:
- A) Cytokinin → Delays ageing.
- B) Auxin → Promotes growth.
- C) Gibberellin → Germination.
- ✅ D) ABA → Causes leaf fall, wilting.
Q74. Which organ in humans is both endocrine and exocrine?
A) Thyroid
B) Pancreas
C) Pituitary
D) Adrenal
Correct Answer: B) Pancreas
Explanation:
- A) Thyroid → Only endocrine.
- ✅ B) Pancreas → Exocrine (enzymes) + Endocrine (insulin, glucagon).
- C) Pituitary → Only endocrine.
- D) Adrenal → Only endocrine.
Q75. The smallest functional unit of nervous system is:
A) Brain
B) Neuron
C) Spinal cord
D) Nerve
Correct Answer: B) Neuron
Explanation:
- A) Brain → Made of neurons.
- ✅ B) Neuron → Smallest structural and functional unit.
- C) Spinal cord → Larger structure.
- D) Nerve → Bundle of neurons.
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