Question

Which photoreceptor is specialized for vision in dim light and allows us to see shapes and movement, and which is specialized for colour and visual acuity?

Answer 1

The retina of the eye consists of two types of photoreceptor cells each containing specific pigments for the absorption of a particular color. The opsins are light-sensitive proteins that give characteristic properties to the photoreceptors. There are two types of photoreceptors known as rods and cones.

Complete answer:
The eye is the visual sensory organ of the human body which consists of an internal layer called the retina. The retina is made up of two types of cells called rods and cones which are photoreceptors. These cells are specialized to absorb light of a particular wavelength. Rods and cones have distinct light-absorbing properties. The rods are specialized to see the objects in dim light like in evening and night. These cells have rhodopsin protein pigment in their rods. This pigment can absorb the reflected dim light from objects in dark. It visualizes the objects in darker shades like grey and black.
The cones, on the other hand, are specialized to absorb the reflected light from objects in normal light or bright light like in day and afternoon. These cells have photopsin protein pigments. These cells are able to see three colors which are red, green, and blue. For each color, there is specific photopsin, like for red it is erythropsin, for blue it is cyanospsin, and for green it is chloropsin. These photopsins work together with color and visual acuity through which we are able to see the beautiful and colorful world around us.

Note: It is observed sometimes that an object is seen as darker in shade in dim light and brighter in shade in normal light. This happens due to switching on and off of the rods and cones. In the dim light, the rods switch on and cones are switched off. On the other hand, in normal light, only cones work and rods are switched off.