more energy and will move faster, and hence diffuse faster, than molecules of the same type in a low-temperature system. The size of the molecule also affects how rapidly it will diffuse. At the same temperature, smaller molecules will move more rapidly than larger molecules because it takes more energy to get the larger molecule moving. Other factors include any charges on the molecule (positive or negative) and the nature of the material that the molecules are moving through.
             Diffusion can occur through a cell membrane. The membrane allows small molecules like water (H2O), oxygen (O2), carbon dioxide (CO2), and others to pass through easily. It is said to be permeable to these molecules. If a cell is floating in a water solution (like the ocean) that has some oxygen dissolved in it, the oxygen molecules will move into the cell. They will also move out of the cell at the same rate, and a dynamic equilibrium will exist. However, if the cell uses some of the oxygen as it comes into the cell, mo
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