NCERT Class X Science Class: Chapter –7. Control and Coordination – Part-4

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Question 20:

The substance that triggers the fall of mature leaves and fruits from plants is due to

(a) Auxin

(b) Gibberellin

(c) Abscisic acid

(d) Cytokine

Answer: C

Mature leaves and fruits plants is due to Abscisic acid

Mature Leaves and Fruits Plants is Due to Abscisic Acid

Mature leaves and fruits plants is due to Abscisic acid

Question 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

Answer: B

Question 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

Answer: C

Image the part of brain

Image the Part of Brain

Image the part of brain

Question 23:

Which of the following is not an involuntary action?

(a) Vomiting

(b) Salivation

(c) Heart beat

(d) Chewing

Answer: D

Question 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

Answer: B

Question 25:

What is the correct direction of flow of electrical impulses?

(a)

direction of flow of electrical impulses (A)

Direction of Flow of Electrical Impulses (A)

direction of flow of electrical impulses (A)

(b)

direction of flow of electrical impulses (B)

Direction of Flow of Electrical Impulses (B)

direction of flow of electrical impulses (B)

(c)

direction of flow of electrical impulses (C)

Direction of Flow of Electrical Impulses (C)

direction of flow of electrical impulses (C)

(d)

Image direction of flow of electrical impulses (D)

Image Direction of Flow of Electrical Impulses (D)

Image direction of flow of electrical impulses (D)

Answer: C