After asking a question, a scientist can form a(n) is an idea that may be proved or disproved by an experiment.

Hypothesis -  it can then be tested to examine if it is correct or false and why

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.