What is true of diffusion? a) diffusion is only important for animal cells b) diffusion requires energy input from the cell c) only water can diffuse across a cell membrane d) molecules move from areas of high concentration to areas of low concentration

(D) Molecules move from areas of high concentration to areas of low concentration

Diffusion is a passive process and doesn't require any energy. Not only water but every small particle can diffuse through the cell membrane. Also, diffusion is an essential process in plant cells too for example in gaseous exchange. An example of diffusion is pouring a drop of ink in the water.

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