cell transport

• Diffusion is the random movement of molecules from an area of higher concentration to an area of lower concentration
• factors that affect diffusion

  • large difference in concentration
  • high temperature
  • large surface area
• osmosis is the movement of water from a high concentration to a low concentration across a partially permeable membrane
• dilute is a solution that contains more water molecules
• concentrated is a solution that contains fewer water molecules
• isotonic = outside concentration of solutes are the same as inside the cell
• hypertonic = outside concentration of solutes higher than inside the cell so water moves out of the cell
• hypotonic = outside concentration of solutes lower than inside the cell so water moves into the cell
• osmosis in animal cells

  • isotonic: normal cells
  • hypotonic: cells swell and burst
  • hypertonic: shrivelled cells
• osmosis in plant cells

  • hypotonic: normal
  • isotonic: flaccid (soft)
  • hypertonic: cytoplasm shrinks from cell wall
• active transport is the movement of substances against a concentration gradient through a partially permeable membrane, requiring energy from respiration