Question

The cones are located in
a.Iris
b.Sclera
c.Choroid
d.Retina

Answer 1

Cones cells are thick and small and are differentiated among different colours in full light and contain visual violet. It is absent in the retina of most of the nocturnal mammal's rats, bats etc.

Complete answer:
Let's discuss the above option and find the proper answer:
-Iris: It is the choroid layer or vascular tunic which separates from the sclerosis layer and inclined towards the inner side and forms the coloured screen. The iris with the help of the pupil helps in the regulation of the amount of light that gets into the eye.
-Sclera: It is made up of the hard, thick, white and opaque fibrous connective tissue. It is a mesoderm in origin. It helps to protect the outer layer of the eyes. It gives protection and maintains the size of the eyeball.
-Choroid: It is the part of the vascular tunic and lies just below the sclerotic layer. It helps to maintain the inner and outer temperature of the eye. It also supplies nutrients to the outer part of the retina. The choroidal circulation helps in the flow of blood in the eyes and contains low oxygen.
-Retina: It is the thin layer of the tissue which helps in the lining of the eyes at the backside in the middle. Its main function is to receive light from the lens and convert it into neural signals. Cones and rods cells are located in the retina as they are the photoreceptors.
Hence, the correct option is D.

Note: Cones helps in the colour vision and also helps in the eye colour sensitivity and they function best in the bright light. The cones contain iodopsin pigment and it is responsible for daylight and colour vision. The innermost ganglionic forms the optic nerve fibres and it developed the optic nerve in each eye and it is connected with the brain.