Movement of substances into and out of cells.

• Diffusion

  The net movement of molecules or ions from an area of higher concentration to an area of lower concentration until equilibrium is reached. A passive process.
• Osmosis


  The net movement of water molecules from an area of higher water potential to an area of lower water potential across a partially permeable membrane until equilibrium is reached. A passive process.
• Active transport


  The movement of molecules or ions from an area of lower concentration to an area of higher concentration against the concentration gradient through a partially permeable membrane. An active process.
• How does temperature affect the rate of diffusion?

  Increased temperature = increased kinetic energy of particle = increased particle movement = increased rate of diffusion.
• How does surface area affect the rate of diffusion?

  Larger surface area = increased surface for particles to pass across = increased rate of diffusion.
• How does the concentration gradient affect the rate of diffusion?

  Steeper concentration gradient (a bigger difference between the the hig concentration and the low concentration) = increased rate of diffusion.
• How does the diffusion distance affect the rate of diffusion?

  Shorter diffusion path = less distance for particles to travel = increased rate of diffusion.