In passive transport, how does increasing temperature generally affect the rate of diffusion of small molecules in a fluid environment?

• A. It decreases the diffusion rate because molecules become denser and collide less frequently.
• B. It stops diffusion entirely once a higher temperature is reached because equilibrium occurs faster.
• C. It has no effect on diffusion rate because diffusion depends only on concentration gradient.
• D. It increases the diffusion rate because molecules have higher 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 energy.
2. Recall that temperature is a measure of the average kinetic energy of molecules; as temperature increases, molecules move faster because they have more kinetic energy.
3. Recognize that faster molecular movement increases the frequency and energy of collisions, which enhances the rate at which molecules spread out or diffuse in a fluid environment.
4. Note that diffusion rate depends on factors such as concentration gradient, temperature, and the properties of the molecules and medium, so temperature does affect diffusion rate.
5. Conclude that increasing temperature generally increases the diffusion rate because molecules move more rapidly, facilitating faster spreading across the concentration gradient.