Answer:
The answer is diffusion.
Explanation:
Diffusion is a process that occurs only in liquids and solids. When diffusion takes place, molecules of a material move from an area of high concentration (where there are many molecules) to an area of low concentration (where there are fewer molecules)until it has reached equilibrium (molecules evenly spread).
In simple diffusion, small neutral (that is non-charged) molecules or lipid soluble molecules pass between the phospholipids to enter or leave the cell, moving from areas of high concentration to areas of low concentration.
Oxygen and carbon dioxide and most lipids enter and leave cells by simple diffusion.
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