Identify the structure that allows light to first enter the eye.

Cornea

Explanation:

The first part of eye through which light enters into the eyes is cornea. Cornea comes in front of the pupil and iris and is made up of transparent layer. It is a curved structure just like a normal glass lenses and hence is able to focus light on retina. It also protects the eyes.  Cornea along with anterior chamber is responsible for 67 percent of the optical power of eye and sends the light towards the pupil.  

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genetic variation will increase because of a new habitat and food source.

explanation: