Cards for diffusion, osmosis and active transport (include key definitions)

Question 1

Diffusion

Answer 1

Diffusion takes place when particles can move from a higher concentration to a lower concentration.

Factors that increase the rate of diffusion include:

1. Concentration gradient: The bigger the difference in concentration, the faster diffusion will be.
2. Temperature: The warmer the fluid, the faster diffusion will be.
3. The surface area of the exchange surface: When the surface area is larger, diffusion will be faster.
4. The distance the molecules must diffuse: If the molecules have to travel a shorter distance, diffusion will be faster.

Question 2

Osmosis

Answer 2

It is the movement of water from a dilute to a more concentrated solute solution through a partially permeable membrane that allows water to pass through. Transport of water from high to low concentration, down a concentration gradient.

Question 3

Active transport

Answer 3

Key points:
Particles are pumped by special “carrier proteins” from an area of LOW concentration to an area of HIGH concentration.

Movement is against the concentration gradient (this is the opposite of diffusion).

This process requires energy.