Question

In the blind spot, where the optic nerves leave the eye
A.Rods and cones are absent.
B.Only cones are present.
C.Only rods are present.
D.Special neurons are present.

Answer 1

Hint:
The optic nerve is located in the back of the eye. The main function of this nerve is to transmit electrical impulses carrying visual information from the eye to the vision centre of the brain. The function of the optic nerve is to transfer visual information from the retina to the vision centres of the brain through electrical impulses.

Complete step by step answer:
The blind spot is the tiny area that is present at the back of each eye. It is a spot where the optic nerve passes through the optic disk and out of the eyes. In addition to this, in this region blood vessels enter the eyes. Blind spots do not contain photo receptor cells i.e., rods and cons. Rods provide vision when the light in the surrounding area is dim while cones are accountable for vision at a higher level of light. When light falls on the blind spot of the retina no image is formed this is due to the absence of rod cells and cone cells in the blind spot of the retina
The blind spot in the retina is devoid of rod cells and cone cells, thus light falling on this region is unable to form any images. As rods and cones are absent in the blind spot in the retina so. The blind spot is present in all vertebrates. While the blind spot is absent in octopuses and cephalopods. The right eye blind spot is situated on the right side of the central vision whereas the left eye blind spot is present on the left side of the central vision. The blind spot of the right and left eye is present on the right side of the centre and left sides of the central vision, respectively.
Hence the correct answer is. Rods and cones are absent..

Option ‘A’ is correct

Note:
The optic nerve is made of Ganglionic cells or nerve cells. Nerve fibres constitute more than one million nerve fibres. Blind spots are caused by the lack of photoreceptor cells in the part of the retina where the optic nerve exits the eye.