Diffusion

Question 1

What is diffusion

Answer 1

Dissolved substances have to pass through the cell membrane to get into or out of a cell. Diffusion is one of the processes that allows this to happen.
Diffusion occurs when particles spread. They move from a region where they are in high concentration to a region where they are in low concentration. Diffusion happens when the particles are free to move. This is true in gases and for particles dissolved in solutions. Particles diffuse down a concentration gradient, from an area of high concentration to an area of low concentration. This is how the smell of cooking travels around the house from the kitchen, for example.

Question 2

Rates of diffusion

Answer 2

The rate of diffusion is increased when:
The distance is decreased
The surface area is increased
The concentration difference (concentration gradient) is increased
Leaves are adapted so that diffusion happens quickly.

Question 3

Diffusion in living organisms

Answer 3

Diffusion happens in living systems, for example, it explains the movement of carbon dioxide in leaves. Osmosis is the movement of water from a high water concentration to a low water concentration through a partially permeable membrane.