The diagram below shows the exchange of carbon dioxide (CO2) and oxygen (O2) between a cell and the blood flowing through a capillary. In this diagram, the molecules of CO2 (represented by x’s) are moving from an area of--

From an area of higher concentration to an area of lower concentration.

Explanation:

The molecules of CO2 are moving from an area of higher concentration to an area of lower concentration. Carbondioxide is produced as waste product in the cell during the process of respiration. This carbondioxide gas is loaded in blood cells because in the cell, concentration of carbondioxide gas is higher while on the other hand the concentration of carbondioxide is lower in the blood cells. This carbondioxide gas exchange in the lungs with oxygen which is required in the process of respiration for the production of energy in the form of ATP molecules. So from the conclusion we can say that CO2 moves from an area of higher concentration to lower concentration.