Question
Differentiate between two types of photosensitive cells i.e. rods and cones.

Answer

The retina contains two types of light sensitive receptor cells:
  • About 5 million cones and about 120 millions rods.
  • Cones, located primarily in the center of the retina in an area called the fovea, function best in bright light and play a key role both in colour vision and in our ability to notice fine detail.
  • Rods are found throughout retina except fovea and function best under lower levels of illumination, so rods help us to see in a darkened room or at night.
  • At increasing distances from the fovea, the density of cones decreases and the density of rods increases.

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