Given a scientific question and its correct answer, generate supporting facts for the answer. This supporting fact can be an explanation for the answer to the given question.

[Q]: Question: What component of cells is present in plant and bacterial cells but not animal cells? Answer: cell wall
[A]: Animal Cell. The shape of an animal cell is not constrained by a rigid cell wall. A bacterial cell is shown above for comparison.

[Q]: Question: What are two of the most common vision problems? Answer: nearsightedness and farsightedness
[A]: Many people have vision problems. Often, the problem is due to the shape of the eyes and how they focus light. Two of the most common vision problems are nearsightedness and farsightedness.

[Q]: Question: Birds evolved from what type of ancestor? Answer: reptile
[A]:
Birds evolved from a reptile ancestor, but modern birds and reptiles are very different. Birds are now the most numerous four-limbed reptiles on Earth.