Given a scientific passage and an answer, generate a question for the given answer.

Passage: Figure 6.11 The frictional force supplies the centripetal force and is numerically equal to it. Centripetal force is perpendicular to velocity and causes uniform circular motion. The larger the F c , the smaller the radius of curvature r and the sharper the curve. The second curve has the same v , but a larger. Answer: centripetal force
What force is perpendicular to velocity and causes uniform circular motion?

Passage: The cornea is the transparent outer covering of the eye. It protects the eye and also acts as a convex lens, helping to focus light that enters the eye. Answer: cornea
What is the transparent outer covering of the eye?

Passage: Figure 5.17 A uniporter carries one molecule or ion. A symporter carries two different molecules or ions, both in the same direction. An antiporter also carries two different molecules or ions, but in different directions. (credit: modification of work by "Lupask"/Wikimedia Commons). Answer: two
A symporter carries how many different molecules or ions in the same direction?