In passive transport, how does increasing temperature generally affect the rate of diffusion across a membrane?

• A. It decreases because membrane pores close at higher temperatures.
• B. It stops once temperature rises above the freezing point of water.
• C. It has no effect because diffusion depends only on the concentration gradient.
• D. It increases because molecules have greater kinetic energy and move faster.

Answer: (D)

Verified step by step guidance

1. Understand that passive transport, specifically diffusion, is the movement of molecules from an area of higher concentration to an area of lower concentration without the use of cellular energy.
2. Recall that temperature affects the kinetic energy of molecules: as temperature increases, molecules move faster because they have more kinetic energy.
3. Recognize that faster molecular movement increases the rate at which molecules collide with and pass through the membrane, thus increasing the diffusion rate.
4. Note that diffusion depends on factors like concentration gradient and temperature, but not on membrane pores closing or freezing conditions in this context.
5. Conclude that increasing temperature generally increases the rate of diffusion across a membrane because molecules move more rapidly, enhancing passive transport.