What are the functions of the iris and the pupil in a human eye?

Hint: The human eye is considered to be one of the finest optical instruments in nature. It has the capability to interpret the incoming electromagnetic waves as images through a complex process. The iris and the pupil are parts of a human eye that work in unison to control the amount of light entering the eye.

Complete step by step solution:
Step 1: Try to explain the changes observed in the pupil and iris to control the amount of light entering the eye.

The pupil is the opening to the eye which is covered by a surface called the cornea. Light entering the eye passes through the pupil before reaching the lens of the eye. The iris is located near the opening of the eye.

The iris controls the amount of light entering the eye. If the light entering the eye is too much then the iris changes so that the pupil constricts and blocks some amount of the unwanted light. If the amount of light is too little, then the iris opens wider so that the pupil dilates and allows more light to enter.

Note: If we were to step out in the sun, the light would be too bright. This scenario is an example of a large amount of light entering the eye. Now if we were to read a book in a dimly lit room then the light entering the eye would be too little. The constriction of the pupil protects the eye from too much light and the dilation of the pupil protects the eye from too little light.