Question

Describe the role of rods and cones in visual perception.

Answer 1

The role of rods in visual perception:

Rhodopsin is a purplish red photosensitive pigment present in the outer segment of the rods. It is made up of protein portion called as opsin (scotopsin) which is combined with an aldehyde of vitamin A called Retinene. On exposure to light, rhodopsin is bleached. Rods are extremely sensitive to light and are responsible for vision in dim light. This is called Scotopic vision.

The role of cones in visual perception:

Cones also contain visual pigments made up of retinene, which is combined with a protein opsin (photopsin). Three pigments each responding to different wavelength are found in man. Color vision is a function of bright light vision and cones are responsible for colour perceptions. Cones function in bright light and the system has more acuity and can perceive colours (Photopic vision).