B2.1.1

Question 1

What is diffusion

Answer 1

Diffusion is the net (overall) movement of particles from a region of high concentration to a region of low concentration. They move down a concentration gradient.

Question 2

When does diffusion stop

Answer 2

Diffusion stops when the concentration of particles is the same everywhere.

Question 3

What type of process is diffusion

Answer 3

Diffusion is a passive process as energy is not transferred.

Question 4

Factors affecting the diffusion rate

Answer 4

Decrease in the distance particles need to move. It takes less time to travel a shorter distance. For example blood capillaries are only one cell thick.

Increase the concentration. The steeper the concentration gradient is, the greater the net movement of particles. For example having a good blood supply takes away the oxygen maintaining a high concentration gradient.

Increase the surface area. This allows more space for diffusion so more particles can move in a period of time. For example the small intestine is highly folded increasing the surface area.