Diffusion

Diffusion is the __________ out of a gas or liquid as their __________ move and mix.

• Diffusion only takes place if there is a __________ in concentration of the substance. This is known as the concentration __________.
  
  
• The substance moves from __________ concentration to area of lower concentration.
  
  
• The higher the concentration gradient the __________ the rate of diffusion.
  
  
• Small molecules diffuse more __________ than large ones.

Copy the diagram below and explain how glucose and oxygen diffuse from capillaries into respiring cells, and how carbon dioxide diffuses from respiring cells into capillaries :