What is colour-blindness?

1.	What is colour-blindness?
Answer» (1) The retina of the human eye contains a large number of light sensitive cells. These cells are of two shapes : (i) rods and (ii) cones. (2) The cone-shaped cells respond to various colours of light when light is bright. (3) Thus, the perception of colour is due to the presence of the cone-shaped cells in the retina. (4) In the retina of some persons, cone-shaped cells responding to certain specific colours are absent. Hence, these persons are unable to distinguish between certain colours, i.e., they are colour-blind. This defect is known as colour blindness.

Answer»

(1) The retina of the human eye contains a large number of light sensitive cells.

These cells are of two shapes : (i) rods and (ii) cones.

(2) The cone-shaped cells respond to various colours of light when light is bright.

(3) Thus, the perception of colour is due to the presence of the cone-shaped cells in the retina.

(4) In the retina of some persons, cone-shaped cells responding to certain specific colours are absent.

Hence, these persons are unable to distinguish between certain colours, i.e., they are colour-blind. This defect is known as colour blindness.

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