12. In many scientific studies, several variables can affect the results. You want to investigate two related areas: 1 Male rats eat more than female rats do. 2 Large rats, regardless of their sex, eat more than smaller rats do. Design an experiment to test ONE of these two ideas.

a- multicellular

b-eukaryotic

c-no cell wall

d-heterotrophic

e-autotrophic

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.

can you make it bigger i can't see it