Glucose and oxygen are used by cells to produce energy for muscle action - this process occurs within each cell. your new workout partner tells you that the supplement he's taking allows him to produce more energy (and have a better workout) because it increases oxygen delivery by increasing the number of cell membrane protein carriers for oxygen (such protein carriers transport substances from the outside of cells to the inside across the cell membrane). what would you say to him?

This situation listed in the question will not happen this way. The energy of cells works differently from the problem, as oxygen is fat-soluble and therefore requires no membrane protein to be transported across the cell membrane. In that case then, the supplement would not be able to increase the amount of oxygen in the cells.

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.