Final answer:
An increase in the concentration difference across a membrane leads to an increased rate of diffusion until dynamic equilibrium is reached.
Step-by-step explanation:
Increases in the concentration difference of an uncharged molecule across a membrane will affect the rate of diffusion. The answer to the student's question, 'How will increases in the concentration difference of an uncharged molecule across a membrane affect the rate of diffusion between two compartments?' is (a) Rate of diffusion increases. This is because the net rate of diffusion is directly proportional to the concentration difference across a membrane. When there is a greater difference, more molecules will move from an area of high concentration to an area of low concentration until dynamic equilibrium is achieved. However, factors such as the mass of the molecules and temperature can also affect the diffusion rate. Larger molecules tend to move more slowly, and changes in temperature can either increase or decrease the molecular movement.