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SolveItNCERT · CBSE · NEET

NCERT Exemplar · Class 10 Science Control and Coordination

53 questions · 53 still being checked

Multiple Choice Questions 21–33 (part 3 of 5)

  1. Exercise 21

    Which of the following statements about transmission of nerve impulse is incorrect?
    (a)
    Nerve impulse travels from dendritic end towards axonal end
    (b)
    At the dendritic end electrical impulses bring about the release of some chemicals which generate an electrical impulse at the axonal end of another neuron
    (c)
    The chemicals released from the axonal end of one neuron cross the synapse and generate a similar electrical impulse in a dendrite of another neuron
    (d)
    A neuron transmits electrical impulses not only to another neuron but also to muscle and gland cells

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    (b)
    (b) is incorrect: the electrical impulse triggers chemical release at the axonal end of the first neuron, not the dendritic end; those chemicals then generate a new impulse in the next neuron's dendrite.

  2. Exercise 22

    Involuntary actions in the body are controlled by
    (a)
    medulla in fore brain
    (b)
    medulla in mid brain
    (c)
    medulla in hind brain
    (d)
    medulla in spinal cord

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    NCERT’s answer
    (c)
    (c) medulla in hind brain. The medulla oblongata sits in the hindbrain and drives involuntary acts — heartbeat, breathing, blood pressure — without conscious control.

  3. Exercise 23

    Which of the following is not an involuntary action?
    (a)
    Vomiting
    (b)
    Salivation
    (c)
    Heart beat
    (d)
    Chewing

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    NCERT’s answer
    (d)
    (d) Chewing. Vomiting, salivation and heart beat are involuntary actions, run without conscious control; chewing is a skeletal-muscle act that a person starts and stops at will.

  4. Exercise 24

    When a person is suffering from severe cold, he or she cannot
    (a)
    differentiate the taste of an apple from that of an ice cream
    (b)
    differentiate the smell of a perfume from that of an agarbatti
    (c)
    differentiate red light from green light
    (d)
    differentiate a hot object from a cold object

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    NCERT’s answer
    (b)
    (b) differentiate the smell of a perfume from that of an agarbatti. Nasal congestion blocks the olfactory receptors; taste, vision and touch stay unaffected by a cold.

  5. Exercise 25

    What is the correct direction of flow of electrical impulses? NCERT_Question_Class10_Science_Exemplar_Ch7_Q25 NCERT_Question_Class10_Science_Exemplar_Ch7_Q25_2 NCERT_Question_Class10_Science_Exemplar_Ch7_Q25_3 NCERT_Question_Class10_Science_Exemplar_Ch7_Q25_4

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    (c)
    (c) Impulse flows dendrite \(\displaystyle \rightarrow\) cell body \(\displaystyle \rightarrow\) axon \(\displaystyle \rightarrow\) axon terminal within each neuron; a synapse joins a terminal to the next neuron's dendrite, never terminal-to-terminal or dendrite-to-dendrite.

  6. Exercise 26

    Which statement is not true about thyroxin?
    (a)
    Iron is essential for the synthesis of thyroxin
    (b)
    It regulates carbohydrates, protein and fat metabolism in the body
    (c)
    Thyroid gland requires iodine to synthesise thyroxin
    (d)
    Thyroxin is also called thyroid hormone

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    NCERT’s answer
    (a)
    (a) Iron is essential for the synthesis of thyroxin. This is false — the thyroid needs iodine, not iron; thyroxin (thyroid hormone) sets carbohydrate, protein and fat metabolism.

  7. Exercise 27

    Dwarfism results due to
    (a)
    Excess secretion of thyroxin
    (b)
    Less secretion of growth hormone
    (c)
    Less secretion of adrenaline
    (d)
    Excess secretion of growth hormone

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    NCERT’s answer
    (b)
    (b) Less secretion of growth hormone. Growth hormone from the pituitary drives bone and body growth in childhood; too little of it gives dwarfism — short stature with normal proportions.

  8. Exercise 28

    Dramatic changes of body features associated with puberty are mainly because of secretion of
    (a)
    oestrogen from testes and testosterone from ovary
    (b)
    estrogen from adrenal gland and testosterone from pituitary gland
    (c)
    testosterone from testes and estrogen from ovary
    (d)
    testosterone from thyroid gland and estrogen from pituitary gland

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    NCERT’s answer
    (c)
    (c) testosterone from testes and estrogen from ovary. These gonadal hormones, not the swapped or wrong-gland pairings in the other options, trigger puberty's secondary sexual changes.

  9. Exercise 29

    A doctor advised a person to take an injection of insulin because
    (a)
    his blood pressure was low
    (b)
    his heart was beating slowly
    (c)
    he was suffering from goitre
    (d)
    his sugar level in blood was high

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    NCERT’s answer
    (d)
    (d) High blood sugar. Insulin, secreted by the pancreas, lowers blood glucose; a person whose blood sugar is high (diabetes) is given an insulin injection to bring it down.

  10. Exercise 30

    The hormone which increases the fertility in males is called
    (a)
    oestrogen
    (b)
    testosterone
    (c)
    insulin
    (d)
    growth hormone

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    NCERT’s answer
    (b)
    (b) Testosterone. Secreted by the testes, it stimulates sperm production and the development of male secondary sexual characters, so it increases fertility in males.

  11. Exercise 31

    Which of the following endocrine glands is unpaired?
    (a)
    Adrenal
    (b)
    Testes
    (c)
    Pituitary
    (d)
    Ovary

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    NCERT’s answer
    (c)
    (c) Pituitary. It is a single gland at the base of the brain; the adrenal, the testes and the ovary each occur as a pair, one on either side.

  12. Exercise 32

    Junction between two neurons is called
    (a)
    cell junction
    (b)
    neuro muscular junction
    (c)
    neural joint
    (d)
    synapse

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    NCERT’s answer
    (d)
    (d) Synapse. It is the tiny gap between the axon terminal of one neuron and the dendrite of the next, across which a nerve impulse crosses chemically.

  13. Exercise 33

    In humans, the life processes are controlled and regulated by
    (a)
    reproductive and endocrine systems
    (b)
    respiratory and nervous systems
    (c)
    endocrine and digestive systems
    (d)
    nervous and endocrine systems

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    (d)
    (d) Nervous and endocrine systems. Electrical impulses give fast control while hormones give slow, sustained regulation, together coordinating all of the body's life processes.