Nervous System, Hormones and Plant Growth Regulators

Attempt the quiz above first, then review every question with its correct answer and a short explanation below.

1. Q1.The control centre of the human nervous system is the:

   • A.brain✓ Correct Answer
   • B.heart
   • C.kidney
   • D.liver

   Explanation: It works with the spinal cord.

2. Q2.Insulin is secreted by the:

   • A.liver
   • B.thyroid
   • C.adrenal gland
   • D.pancreas✓ Correct Answer

   Explanation: It lowers blood sugar.

3. Q3.The structural and functional unit of the nervous system is the:

   • A.neuron✓ Correct Answer
   • B.nephron
   • C.alveolus
   • D.sarcomere

   Explanation: It carries nerve impulses.

4. Q4.Reflex actions are controlled mainly by the:

   • A.cerebrum
   • B.spinal cord✓ Correct Answer
   • C.liver
   • D.heart

   Explanation: This gives a rapid response without waiting for the brain.

5. Q5.Thyroxine is secreted by the:

   • A.thyroid gland✓ Correct Answer
   • B.pituitary gland
   • C.pancreas
   • D.adrenal gland

   Explanation: It needs iodine for its synthesis.

6. Q6.The emergency hormone that prepares the body for "fight or flight" is:

   • A.adrenaline✓ Correct Answer
   • B.insulin
   • C.thyroxine
   • D.oestrogen

   Explanation: It is secreted by the adrenal glands.

7. Q7.Which plant hormone promotes cell elongation and growth?

   • A.abscisic acid
   • B.ethylene
   • C.cytokinin
   • D.auxin✓ Correct Answer

   Explanation: Auxin accumulates on the shaded side of a stem.

8. Q8.The hormone that promotes stem elongation and seed germination is:

   • A.abscisic acid
   • B.ethylene
   • C.gibberellin✓ Correct Answer
   • D.florigen only

   Explanation: It breaks seed dormancy.

9. Q9.Cell division in plants is promoted by:

   • A.abscisic acid
   • B.ethylene
   • C.auxin only
   • D.cytokinin✓ Correct Answer

   Explanation: It delays senescence of leaves.

10. Q10.The gaseous plant hormone that hastens fruit ripening is:

    • A.auxin
    • B.gibberellin
    • C.ethylene✓ Correct Answer
    • D.cytokinin

    Explanation: Raw bananas ripen faster beside ripe ones.

11. Q11.The pituitary gland is called the "master gland" because it:

    • A.is the largest gland
    • B.controls the activity of other endocrine glands✓ Correct Answer
    • C.is found in the stomach
    • D.makes bile

    Explanation: It lies at the base of the brain.

12. Q12.The part of the brain that maintains balance and posture is the:

    • A.cerebrum
    • B.medulla oblongata
    • C.hypothalamus
    • D.cerebellum✓ Correct Answer

    Explanation: It coordinates voluntary movements.

13. Q13.Involuntary actions such as breathing and heartbeat are controlled by the:

    • A.cerebrum
    • B.medulla oblongata✓ Correct Answer
    • C.cerebellum
    • D.olfactory bulb

    Explanation: It connects the brain to the spinal cord.

14. Q14.Diabetes mellitus is caused by a deficiency of:

    • A.thyroxine
    • B.insulin✓ Correct Answer
    • C.adrenaline
    • D.growth hormone

    Explanation: Blood glucose then stays high.

15. Q15.Goitre is caused by a deficiency of:

    • A.iodine✓ Correct Answer
    • B.iron
    • C.calcium
    • D.vitamin C

    Explanation: The thyroid gland enlarges without enough iodine.

16. Q16.Growth of a plant shoot towards light is called:

    • A.geotropism
    • B.phototropism✓ Correct Answer
    • C.hydrotropism
    • D.thigmotropism

    Explanation: Shoots are positively phototropic.

17. Q17.The gap between two neurons is called the:

    • A.axon
    • B.dendrite
    • C.synapse✓ Correct Answer
    • D.node of Ranvier

    Explanation: Neurotransmitters cross it.

18. Q18.Under-secretion of growth hormone in childhood causes:

    • A.gigantism
    • B.diabetes
    • C.dwarfism✓ Correct Answer
    • D.goitre

    Explanation: Over-secretion causes gigantism.

19. Q19.The myelin sheath around axons:

    • A.digests nerve cells
    • B.stores glucose
    • C.insulates the axon and speeds up impulse conduction✓ Correct Answer
    • D.makes hormones

    Explanation: It is made of fatty material.

20. Q20.The plant hormone that promotes dormancy and helps in stomatal closure under stress is:

    • A.auxin
    • B.gibberellin
    • C.cytokinin
    • D.abscisic acid✓ Correct Answer

    Explanation: It is known as the stress hormone.