Question

_____ Pigment enables us to see in the dark.

Answer 1

The eye is an organ that allows vision and reacts to the light. The rod and cone cells present in the eye enables the light perception and vision along with different colours and 3D vision. It is part of our sensory nervous system.

Complete answer:
The retina has two types of photoreceptors i.e. rods and cones. Rods and cones both contain photopigments. Photopigments are light-sensitive proteinS that enable the vision and the colours we observe. Cones help with the daylight vision, while rods help with the vision in dim light or dark. The photopigment present within the rods is known as rhodopsin which absorbs the light rays and helps us to see around us in the dim light. It is a purplish-red pigment and a G-protein-coupled receptor (GPCR). It belongs to opsins. When rhodopsin is exposed to light, it is immediately photobleached. In humans, it is regenerated fully in about 30 minutes, after which rods are more sensitive.

Additional Information: The point where optic nerve and retina meet, there are no sensory nerve cells and is regarded as the blind spot as no vision can occur there due to lack of sensory nerve cells- rods and cones. There are a total of 6 muscles in the eyes that help with the movement of the eye because of which our eye can focus on 50 different things at the same time.
Note: The rhodopsin is present in the inner lining of the eye. It has two major functions i.e. it also participates in the formation of photoreceptor cells along with the first activity that occurs during perception of light.