Japhet knows that while rods are spread throughout the retina, cones are concentrated around the fovea. from this knowledge, what might japhet infer?

that is wrong, its not thymus.

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.