Question

Blind spot refers to the:
A. region where the human eye goes blind
B. region where the retina is insensitive to light
C. region where light enters the human eye
D. region where retina is highly sensitive to light and hence does not have the ability to detect
light

Answer 1

Hint:- The eyes contain numerous photosensitive cells spread over its various parts. These photosensitive cells help in the formation of an image. The photosensitive cells are not present in the region of the blind spot.

Complete answer:
Blind spot is the small portion present in the eye. It is present where the optic nerves leave the retina of the eye. There are no photoreceptors present in this area making it a region insensitive to the light. The photoreceptors cells include the rods and cones which help in providing the night and daylight vision respectively. The optic nerve is connected to our brain. It helps in sending the signals to the brain where they get processed and an image is formed. As the blind spot is unable to detect the light it leads to no image formation in that field of vision. The rods present in the eye helps in the night time vision. Rods make our vision little clear at night. Even a single beam of light can be detected by the rods. The cones provide us with our daylight vision. They don’t work when there is no amount of light or less amount of light is present. The number of rods and cones present in our eyes are balanced. In owls, there is the presence of more rods than cones as they need the night time vision to see.
So, the answer is option (B) ‘region where the retina is insensitive to light’.

Note:- The cornea is the outer covering of the iris which protects it. The light beam passes through the lens of the eye and reaches the vitreous humour where the blood vessels are present that connect to the retina of the eye. The image is then transferred from the retina to the optic nerve from where it reaches the brain for the final image formation.