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12
Rearrange the following in the correct order of involvement in electrical impulse movement.
Explanation

The correct order of involvement in electrical impulse movement.

(i) Dendrites (ii) Cell body (iii) Axon (iv) Axon terminal (v) Synaptic knob

13
Comment upon the role of ear in maintaining the balance of the body and posture.
Explanation

The vestibular system is the sensory apparatus of the inner ear that helps the body maintain its postural equilibrium. There are two sets of organs in inner ear, or labyrinth-The semicircular canals which respond to rotational movements; and the utricle and saccule within the vestibule, which respond to changes in the position of the head with respect to gravity. Each semicircular canal contains hair cells. Rotation of the head causes a flow of fluid, which in turn causes displacement of the top portion of hair cells embedded in jelly-like capula. Utricle and saccule called otolithic organs contain hair cells blanketed with ting stones called otoconia. When the head is tilted or body position is changed the displacement of stones causes the hair cells to bend.

14
Which cells of the retina enable us to see coloured objects around us?
Explanation
Cone cells of retina unable us to see the colours. There are three types of cones which possess their own characteristic photopigments that respond to red, green and blue light.
15
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.
Explanation

External Auditory canal $\rightarrow$ Eardrum $\rightarrow$ Malleus $\rightarrow$ The reception and transmis sion of sound wares occurs in following order-

Incus $\longrightarrow$ Stapes $\longrightarrow$ Cochlea $\longrightarrow$ Cochlear nerve

16
During resting potential, the axonal membrane is polarised, indicate the movement of +ve and -ve ions leading to polarisation diagrammatically.
Explanation