Question

Function of iris is to (a) move lens forward and backward (b) refract light rays (c)...

Function of iris is to

(a) move lens forward and backward

(b) refract light rays

(c) bring about movements of eye lids

(d) alter the size of pupil.

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Answer #1

Iris is a thin, circular structure in the eye.Iris contains eye colour pigments and smooth muscles.Eye colour is defined by the iris.There is a round opening at the center of the iris through which light enters the interior portion of the eye that is the pupil.The iris contains circular muscle that constrict and radial muscle that diliate the pupil.It acts like the diaphragm of a camara, dilating and constricting the pupil to alllow more or less light into the eye.Iris regulates the amout of light that enters eye.

So it states that iris is responsible for controling the diameter and size of pupil.

(d) is the correct answer.

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