Transport in cells

• Diffusion is the net random movement of particles from an area of high concentration to an area of low concentration
• If the rate at which carbon dioxide diffuses into mesophyll cells increase, there will be an increased carbon dioxide concentration in the air and an increased number of stomata that are open
• The human lungs:

  The lungs contain many alveoli which increase the surface area of the lungs, therefore, more diffusion can happen at once

  The cell walls of the alveoli are one cell thick which provides a short diffusion path.

  They have a good blood supply which maintains a concentration gradient.
• Water molecules move into the root hair cell by osmosis
• Nitrate ions move into the root hair cell by active transport.

  Nitrate ions move from an area of low concentration to an area of high concentration. This process requires energy