Question

Color to the eye is imparted by
(a) Lens
(b) Pupil
(c) Iris
(d) Vitreous humour

Answer 1

Hint: A flat and ring- shaped membrane behind the cornea of the eye with an adjustable circular opening is known to impart eye color to an individual. Together with pupil it is responsible for regulating the amount of light that gets into the eye.

Complete answer:
Iris surrounds the pupil and regulates the amount of light entering the eye by controlling the size of the pupil. It has cells of varying colors and hence imparts color to the eye. The muscular iris shrinks the pupil if there is too much light and widens if there is not enough. This is an involuntary function controlled by the brain. Iris is made entirely of connective tissue and smooth muscle fiber. To make the iris opaque, it is coated with the pigment melanin, in varying degrees. The iris color determines what color an eye will be green, light blue, dark blue hazel etc. These colors are determined by how much brown pigment is on the back of the iris. In optical terms, the pupil is the eye’s aperture, while the iris is the diaphragm.
So, the correct answer is 'Iris'.

Additional information:
- The iris consists of two layers: front pigmented fibrovascular layer known as a stroma and beneath the stroma pigmented epithelial cells.
- The iris is divided into two major regions: the pupillary zone and the ciliary zone. The former is the inner region whose edge forms the boundary of the pupil and the later refers to the rest of the iris that extend to its origin at the ciliary body.
- The quantity of melanin pigment in the iris is one factor in determining the phenotypic eye color of a person.

Note:
- A person’s eye color is actually the color one of one’s iris, cornea being transparent and cornea being transparent and white sclera entirely outside the area of interest.
- Lens is a transparent and crystalline structure present in the eye which focuses the light rays to form an image on the retina.
- Pupil is an aperture in the eye which is surrounded by iris. Light enters the eye through the pupil.
- Vitreous humour is the transparent gel present in the space between lens and retina.