Control and Coordination Part 4: MCQs (Q76–Q100)
📘 Control and Coordination – MCQs (Class 10 Science)
🔹 Part 4: Questions 76–100
Q76. The junction between two neurons is called:
A) Axon
B) Dendrite
C) Synapse
D) Node of Ranvier
Correct Answer: C) Synapse
Explanation:
- A) Axon → Long fibre of neuron.
- B) Dendrite → Receives signals.
- ✅ C) Synapse → Junction where impulses pass chemically.
- D) Node of Ranvier → Gap in myelin sheath.
Q77. Which hormone is known as the “emergency hormone”?
A) Thyroxine
B) Insulin
C) Adrenaline
D) Estrogen
Correct Answer: C) Adrenaline
Explanation:
- A) Thyroxine → Metabolism.
- B) Insulin → Sugar regulation.
- ✅ C) Adrenaline → Prepares body for “fight or flight”.
- D) Estrogen → Female sex hormone.
Q78. What is the function of the cerebellum?
A) Thinking
B) Balance and posture
C) Controlling emotions
D) Breathing
Correct Answer: B) Balance and posture
Explanation:
- A) Thinking → Cerebrum.
- ✅ B) Cerebellum → Maintains balance and coordination.
- C) Emotions → Hypothalamus.
- D) Breathing → Medulla.
Q79. Which plant hormone promotes the ripening of fruits?
A) Cytokinin
B) Gibberellin
C) Ethylene
D) Auxin
Correct Answer: C) Ethylene
Explanation:
- A) Cytokinin → Cell division.
- B) Gibberellin → Elongation, germination.
- ✅ C) Ethylene → Gaseous hormone, speeds ripening.
- D) Auxin → Growth.
Q80. In reflex action, the impulse is carried from receptor to spinal cord by:
A) Motor neuron
B) Sensory neuron
C) Relay neuron
D) Effector
Correct Answer: B) Sensory neuron
Explanation:
- A) Motor → From spinal cord to effector.
- ✅ B) Sensory → From receptor to spinal cord.
- C) Relay → Within spinal cord.
- D) Effector → Performs action.
Q81. Which part of the eye focuses light on the retina?
A) Cornea
B) Iris
C) Lens
D) Pupil
Correct Answer: C) Lens
Explanation:
- A) Cornea → Refracts light, but not focusing.
- B) Iris → Controls light entry.
- ✅ C) Lens → Adjusts curvature, focuses light on retina.
- D) Pupil → Opening, not focusing.
Q82. The hormone responsible for increasing the level of sugar in blood is:
A) Insulin
B) Glucagon
C) Adrenaline
D) Thyroxine
Correct Answer: B) Glucagon
Explanation:
- A) Insulin → Decreases sugar.
- ✅ B) Glucagon → Increases sugar by breaking glycogen.
- C) Adrenaline → Indirectly increases sugar in emergencies.
- D) Thyroxine → Metabolism.
Q83. Which type of movement in plants is not directional?
A) Tropic movement
B) Nastic movement
C) Geotropism
D) Phototropism
Correct Answer: B) Nastic movement
Explanation:
- A, C, D → Directional growth movements.
- ✅ B) Nastic → Non-directional, e.g., Mimosa pudica folding.
Q84. Which gland controls all other endocrine glands?
A) Thyroid
B) Pituitary
C) Pancreas
D) Adrenal
Correct Answer: B) Pituitary
Explanation:
- A) Thyroid → Controlled by pituitary.
- ✅ B) Pituitary → Master gland, regulates others.
- C) Pancreas → Sugar regulation only.
- D) Adrenal → Stress hormone only.
Q85. The growth of a plant towards light is due to:
A) Uneven distribution of auxin
B) Even distribution of auxin
C) Cytokinin activity
D) Ethylene release
Correct Answer: A) Uneven distribution of auxin
Explanation:
- ✅ A) Auxin moves to shaded side → causes bending towards light.
- B) Even → Would not cause bending.
- C, D → Not involved in phototropism.
Q86. Which part of the brain regulates heartbeat and breathing?
A) Cerebellum
B) Medulla oblongata
C) Cerebrum
D) Pons
Correct Answer: B) Medulla oblongata
Explanation:
- A) Cerebellum → Balance.
- ✅ B) Medulla → Controls involuntary functions like heartbeat.
- C) Cerebrum → Thinking.
- D) Pons → Relay.
Q87. Which hormone induces seed germination?
A) Gibberellin
B) Auxin
C) Cytokinin
D) Abscisic acid
Correct Answer: A) Gibberellin
Explanation:
- ✅ A) Breaks dormancy, promotes germination.
- B) Auxin → Growth.
- C) Cytokinin → Cell division.
- D) ABA → Inhibits germination.
Q88. In human nervous system, the longest fibre is:
A) Dendrite
B) Axon
C) Synapse
D) Nucleus
Correct Answer: B) Axon
Explanation:
- A) Dendrite → Short, branched.
- ✅ B) Axon → Long fibre carrying impulses away.
- C, D → Not fibres.
Q89. Which part of the brain is responsible for intelligence and memory?
A) Cerebrum
B) Medulla
C) Cerebellum
D) Hypothalamus
Correct Answer: A) Cerebrum
Explanation:
- ✅ A) Cerebrum → Higher mental functions.
- B) Medulla → Involuntary functions.
- C) Cerebellum → Balance.
- D) Hypothalamus → Hunger, thirst.
Q90. Which type of response is shown by tendrils climbing a support?
A) Phototropism
B) Thigmotropism
C) Hydrotropism
D) Chemotropism
Correct Answer: B) Thigmotropism
Explanation:
- A) Phototropism → Light.
- ✅ B) Thigmotropism → Response to touch, tendrils coil around support.
- C, D → Not related.
Q91. Which part of a neuron receives impulses?
A) Axon
B) Dendrite
C) Synapse
D) Axon terminal
Correct Answer: B) Dendrite
Explanation:
- A) Axon → Sends impulses.
- ✅ B) Dendrites → Receive impulses.
- C) Synapse → Junction.
- D) Axon terminal → Transmits signals to next cell.
Q92. Which plant hormone is responsible for apical dominance?
A) Auxin
B) Cytokinin
C) Gibberellin
D) Ethylene
Correct Answer: A) Auxin
Explanation:
- ✅ A) Auxin in apical bud suppresses growth of lateral buds.
- B, C, D → Not responsible.
Q93. Which gland secretes insulin?
A) Pituitary
B) Adrenal
C) Pancreas
D) Thyroid
Correct Answer: C) Pancreas
Explanation:
- A) Pituitary → Growth hormone.
- B) Adrenal → Adrenaline.
- ✅ C) Pancreas → Islets of Langerhans secrete insulin.
- D) Thyroid → Thyroxine.
Q94. Which is not an involuntary action?
A) Blinking
B) Breathing
C) Heartbeat
D) Reading a book
Correct Answer: D) Reading a book
Explanation:
- A, B, C → Involuntary or reflex.
- ✅ D) Reading → Voluntary action.
Q95. Which hormone controls metamorphosis in frogs?
A) Insulin
B) Thyroxine
C) Adrenaline
D) Testosterone
Correct Answer: B) Thyroxine
Explanation:
- A) Insulin → Blood sugar.
- ✅ B) Thyroxine → Controls frog metamorphosis.
- C, D → Not related.
Q96. Which organ in humans is affected in goitre?
A) Pancreas
B) Pituitary
C) Thyroid
D) Adrenal
Correct Answer: C) Thyroid
Explanation:
- A) Pancreas → Diabetes.
- B) Pituitary → Growth disorders.
- ✅ C) Thyroid → Iodine deficiency causes goitre.
- D) Adrenal → Stress hormone.
Q97. Which hormone regulates female reproductive cycle?
A) Insulin
B) Estrogen and progesterone
C) Testosterone
D) Adrenaline
Correct Answer: B) Estrogen and progesterone
Explanation:
- A) Insulin → Sugar.
- ✅ B) Female reproductive hormones regulate cycle.
- C) Testosterone → Male hormone.
- D) Adrenaline → Stress.
Q98. Which plant movement occurs due to stimulus of gravity?
A) Phototropism
B) Geotropism
C) Thigmotropism
D) Nastic
Correct Answer: B) Geotropism
Explanation:
- A) Phototropism → Light.
- ✅ B) Geotropism → Roots grow downward due to gravity.
- C, D → Not gravity-related.
Q99. In human eye, the image is formed on:
A) Lens
B) Iris
C) Retina
D) Cornea
Correct Answer: C) Retina
Explanation:
- A) Lens → Only focuses.
- B) Iris → Regulates light entry.
- ✅ C) Retina → Light-sensitive layer where image forms.
- D) Cornea → Refraction, no image.
Q100. Which part of the neuron transmits impulse away from cell body?
A) Dendrite
B) Axon
C) Synapse
D) Nucleus
Correct Answer: B) Axon
Explanation:
- A) Dendrite → Toward cell body.
- ✅ B) Axon → Away from cell body to next neuron or effector.
- C) Synapse → Junction.
- D) Nucleus → Control centre, not conduction.
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