Small, uncharged substances enter and leave the cell membrane through the process of

Simple Diffusion Across the Cell (Plasma) Membrane. The structure of the lipid bi-layer allows small, uncharged substances such as oxygen and carbon dioxide, and hydrophobic molecules such as lipids, to pass through the cell membrane, down their concentration gradient, by simple diffusion.

identify the dna change shown in the diagram and explain how that change can result in the increased genetic diversity often seen among siblings.

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