Diffusion

What is diffusion?

Diffusion is the random movement of particles from a region of high concentration to a region of low concentration.

What type of transport is diffusion considered?

Diffusion is a passive method of transport across a cell membrane.

Does diffusion require energy from ATP?

No, diffusion does not require ATP or energy from respiration.

What type of molecules can pass through membranes via simple diffusion?

Simple diffusion is limited to small, non-polar or lipid-soluble molecules.

Give examples of molecules that cross membranes by simple diffusion.

Oxygen, carbon dioxide, and fat-soluble vitamins (A, D, E, and K) are examples.

What factors affect the rate of diffusion?

Surface area, length of diffusion pathway, steepness of concentration gradient, and temperature.

How does surface area affect diffusion?

A higher surface area increases the rate of diffusion by providing more places for diffusion to occur.

Why does a shorter diffusion pathway increase diffusion rates?

Shorter diffusion pathways allow substances to move more quickly.

What happens to diffusion rates when the temperature increases?

Higher temperatures increase the kinetic energy of particles, thus speeding up diffusion.

What factors can affect membrane permeability?

Salt concentration, presence of detergents, and organic solvents.