The diagram is a model of one way that materials move across the cell membrane. Oxygen molecules are
represented by two red circles. Carbon dioxide molecules
are represented by a gray circle with two red circles
attached. The left-hand side of the diagram shows the
beginning concentrations of the two types of molecules.
The right-hand side shows how the molecules have moved
over time.
sss
Which sentence best explains the movement of the oxygen molecules over
time?