Diffusion

1. Net movement of particles from a region of high to low concentration down a concentration gradient as a result of their random movement.

1.1. Energy from the kinetic energy of the molecules.

2. Solutes and gases such as carbon dioxide and oxygen diffuse into and out of cells across the cell membrane.

2.1. Needed for metabolic reactions such as respiration and photosynthesis.

2.2. Processes would not occur without them and cell would die.

3. Factors

3.1. Surface area

3.1.1. As it increases, the rate of diffusion increases as there is more space available for the substance to diffuse through.

3.2. Temperature

3.2.1. As it increases, the rate of diffusion increases as the molecules gain more kinetic energy and move faster.

3.3. Concentration gradient

3.3.1. As it increases, the rate of diffusion increases.

3.4. Diffusion distance

3.4.1. As it increases, the rate of diffusion slows as molecules must travel further.