instruction:
Given a scientific question, generate a correct answer to it.
question:
Sometimes two or more distinct phenotypes can each have their advantages and be selected for by natural selection; this is known as what?
answer:
diversifying selection

question:
Oxygen reaches what veinless part of the eye by diffusing through its tear layer?
answer:
cornea

question:
Glass breaking is an example of what type of change that doesn't affect the makeup of matter?
answer:
physical