Question

A list of steps involves the mechanism of vision is given below in random order.

(i) Neural impulses are analyzed and the image formed on the retina is recognized by visual cortex.

(ii) Membrane permeability changes.

(iii) Ganglion cells are excited.

(iv) Bipolar cells are depolarized.

(v) Action potentials (impulse) are transmitted by optic nerves to the visual cortex.

(vi) Potential differences are generated in the photoreceptor cells.

(vii) Light energy causes a change in the shape of rhodopsin, leading to the dissociation of retinal (an aldehyde of vitamin A) from opsin (a protein).

(viii) Structure of opsin is changed.

Which of the following options represents these events in the correct order?

• A. (i), (ii), (iii), (iv), (v), (vi), (vii), (viii)
• B. (viii), (vii), (vi), (v), (iv), (iii), (ii), (i)
• C. (i), (iv), (iii), (ii), (vii), (viii), (vi), (v)
• D. (vii), (viii), (ii), (vi), (iv), (iii), (v), (i)

Answer 1

Answer: (D)

(vii), (viii), (ii), (vi), (iv), (iii), (v), (i)

The correct order of the mechanism of vision is :

1. Light energy causes a change in the shape of rhodopsin, leading to the dissociation of retinal (an aldehyde of vitamin A) from opsin (a protein).

2. Structure of opsin is changed.

3. membrane permeability changes.

4. The potential difference is generated in the photoreceptor cells.

5. Bipolar cells are depolarized.

6. Ganglion cells are excited.

7. Action potentials (impulse) are transmitted by optic nerves to the visual cortex.

8. Neural impulses are analysed and the image formed on the retina is recognised by visual cortex.

So, the correct answer is 'Option D- (vii),(viii),(ii),(vi),(iv),(iii),(v),(i)'.