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Animation: How Diffusion Works
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View the animation below, then complete the quiz to test your knowledge of the concept.

1Simple diffusion is defined as the movement of
A)molecules from areas of higher concentration to areas of lower concentration.
B)molecules from areas of lower concentration to areas of higher concentration.
C)water molecules across a membrane.
D)gas molecules across a membrane.
E)gas or water molecules across a membrane.

2When sugar is mixed with water, equilibrium is reached when
A)molecules of sugar stop moving.
B)water and sugar molecules are moving at the same speed.
C)the dissolved sugar molecules are evenly distributed throughout the solution.
D)there are the same number of water molecules as dissolved sugar molecules.
E)two tablespoons of coffee are added.

3The rate of diffusion is affected by which of the following?
B)size of molecules
C)steepness of the concentration gradient
D)A and B
E)A, B and C

4The molecules in a solid lump of sugar do not move.

5Diffusion is one of the processes whereby materials are exchanged between a cell and its environment.

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