Explain what scientists are able to learn about evolution when comparing different fossils in different rock layers? Use these three terms in your related, extinction, and transition. You must write at least two complete sentences.

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.