Question

What are photoreceptors?

Answer 1

These types of cells are present in the retina region of the eye. These are the cells that are responsible for entrapping light. In the presence of light, these cells get bleached which generates an action potential in the optic nerve.

Complete answer:
These are the cells that get stimulated by light energy, and the overall stimulation of these cells generates an action potential which ultimately gets processed by the brain and an image is formed in front of us. This phenomenon is known as transduction of light.
There are two types of photoreceptors present in the eye- Rods and Cones. Both these cells contain certain chemicals known as photopigments that are stimulated in presence of light.
The Rod cells are cylindrical in shape and are responsible for dim light vision mainly. They contain the pigment rhodopsin. The resolution of the images in twilight vision is low.
The Cones are responsible for color vision. They mainly detect three types of principal colors- blue, green and yellow. The stimulation of these colors altogether gives us the white color. And the combination of these three colors at varied proportions help us to detect the rest of the colors.
The intensity and the quality of image formed is always related to the amounts of these photoreceptor cells that get bleached.

Note:
The plants also have photoreceptor cells which help them to detect light and perform some notable metabolic reactions. But when we are asked to describe only photoreceptor cells, we will narrate about the retinal photoreceptor cells by default until and unless it is mentioned to describe the photoreceptor cells in plants.