transport across cell membranes

• what are the 2 molecules present in cell membrane?

  proteins and phospholipids
• what is meant by selectively permeable?


  Selectively permeable means that the membrane permits free passage of some materials and restricts the passage of others.
• describe active transport in terms of gradient


  goes against gradient
• describe passive transport in terms of gradient 


  goes down gradient
• describe active transport in terms of energy use


  does use energy
• describe passive transport in terms of energy use


  does NOT use energy
• what is the definition of osmosis 


  Osmosis is the movement of water molecules from a higher water concentration to a lower water concentration, through a selectively permeable membrane.
• what is the definition of diffusion

  Diffusion is the movement of molecules along a concentration gradient from a higher to a lower concentration
• what is the definition for hypertonic?


  less water concentration that in cell
• what is the definition for hypotonic?


  more water concentration than in cell
• what is the definition for isotonic?


  same water concentration that in cell
• what happens to plant cells in higher water concentration?


  become turgid
• what happens to plant cells in lower water concentration?


  become plasmolysed
• what happens to animal cells in higher water concentration?


  swell up and burst
• what happens to animal cells in lower water concentration?


  shrink
• describe a turgid cell 


  enlarged and swollen with water
• describe a plasmolysed cell 


  Description of a plant cell in which the vacuole has shrunk and the membrane has pulled away from the wall due to water loss by osmosis.