AQA GCSE Biology B3

  • Created by: Natalie
  • Created on: 09-04-13 20:00

Summary Notes

Entering Cells

  • Osmosis is the movement of water from a dilute concentration to a concentrated solution.
  • Water enters root hair cells by osmosis.
  • Animal cells burst in a dilute concentration, because too much water enters by osmosis.
  • Plant cells don't burst in a dilute concentration because of the cell wall.
  • Cells shrink if they are placed into a concentrated solution because water leaves by osmosis.
  • Osmosis needs a partially permeable membrane.
  • Diffusion and osmosis are passive, so happen without energy.
  • Active transport requires energy.
  • Active transport goes against the concentration gradient.
  • Alveoli are needed to get oxygen into the blood and carbon dioxide out of the blood.
  • Exchange surfaces are adapted for efficient diffusion.

Getting Around

  • Ventilation exchanges gases in the lungs.
  • The diaphragm and rib muscles are needed for ventilation.
  • The heart pumps blood around the body.
  • Arteries carry blood away from the heart


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