NCERT Class 11-Biology: Chapter –21 Neural Control and Coordination Part 2

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Question 10:

The part of internal ear responsible for hearing is

a. Cochlea

b. Semicircular canal

c. Utriculus

d. Sacculus

Answer: (a)

Question 11:

The organ of corti is a structure present in

a. External ear

b. Middle ear

c. Semi-circular canal

d. Cochlea

Answer: (c)

Very Short Answer Type Questions

Question 1:

Rearrange the following in the correct order of involvement in electrical impulse movement-

Synaptic knob, dendrites, cell body, Axon terminal, Axon

Answer:

The correct order of involvement of the given parts of neuron in electrical impulse is-

Question 2:

Comment upon the role of ear in maintaining the balance of the body and posture.

Answer:

The inner ear is responsible for maintaining the balance of the body and posture. The semicircular canals and the vestibule are the two parts of the inner ear which are involved in balancing the body and maintaining its equilibrium.

Question 3:

Which cells of the retina enable us to see coloured objects around us?

Answer:

The cone cells present inside the retina enable us to see coloured objects around us. They are photoreceptor cells of the eyes of the vertebrates which work best in relatively bright light.

Question 4:

Arrange the following in the order of reception and transmission of sound wave from the ear drum:

Cochlear nerve, external auditory canal, ear drum, stapes, incus, malleus, cochlea.

Answer:

External auditory canal → Ear Drum → Malleus → Incus → Stapes → Cochlea → Cochlear nerve

So, the order of reception and transmission of sound wave from the ear drum is –

Ear Drum → Malleus → Incus → Stapes → Cochlea → Cochlear nerve

Question 5:

During resting potential, the axonal membrane is polarised, indicate the movement of and ions leading to polarisation diagrammatically.

Answer:

In response to a signal, the soma end of the axon becomes depolarized.

The depolarization spreads down the axon. Meanwhile, the first part of the membrane repolarizes. Because positive channels are inactivated and additional positive channels have opened, the membrane cannot depolarize again.

The action potential continues to travel down to the axon.

Question 6:

Name the structures involved in the protection of the brain.

Answer:

Following structures are involved in the protection of the brain:

Skull and Cerebrospinal Fluid

Question 7:

Our reaction like aggressive behaviour, use of abusive words, restlessness etc. are regulated by brain, name the parts involved.

Answer:

The limbic system; along with hypothalamus; is involved in controlling extreme emotions.

Question 8:

What do grey and white matter in the brain represent?

Answer:

Grey matter – The cerebral cortex is referred to as Grey matter due to its greyish appearance. It is the layer of cells covering the cerebral hemisphere and is thrown into prominent folds. There are neuron cell bodies concentrated, hence giving the grey colour.

White matter – Fibres of the tract are covered with myelin sheath. It constitutes the inner part of the cerebral hemisphere. They give an opaque white appearance to the layer.

Question 9:

Where is the hunger centre located in human brain?

Answer:

The hunger centre is located in hypothalamus in human brain. It contains many centers which control the urge for eating and drinking.

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