Question

What is the term used for the photoreceptor cells of the retina which is sensitive to colour?

Answer 1

Hint: In the eye from the choroid side the retina consists of three layers known as pigment cell layers, photoreceptor layer and nerve cell layer. The photoreceptor layer consists of rods and cones which have photosensitive pigment present in them.

Complete Answer:
The photoreceptor layer of the retina consists of rods and cones. The rod consists of rod cells whereas cones consist of cone cells. There are seven million cones present in the retina which function in bright light condition and it is sensitive to colours. It helps in bright light vision and colour vision. Cones consist of photosensitive pigment photopsin which forms by different types of opsin like iodopsin, porphyrin and cyanopsia which combine with retinal to form the pigment. Cones detect fine detailing of the object and rapid changes in the image, just because of their faster response to stimuli.

Additional Information:
There are 120 million rods present in the retina consisting of photosensitive pigment rhodopsin. The rod works in dim light conditions by which the animal is enabled to see in case of low light. In case of strong light condition the opsin and retinene which present in the eye as photosensitive pigment get separated which get reformed in dim light condition with the help of enzyme retinene isomerase. It is not able to detect fine detailing as cones due to lesser response to stimuli as compared to rods.

Note:
As rods work in dim light conditions, therefore, nocturnal animals have a large number of rods in their retina.
Some animals consist of four types of photoreceptors in the cones and the fourth photoreceptor works for ultraviolet light.