B1.3 transport in cells

• Diffusion- 


  When something travels from and area of high concentration to an area of low concentration
• Substances can move across a cell membrane by diffusing
• Osmosis-


  when water diffuses from a high concentrated area to a less concentrated area through a partially permeable membrane
• Active transport-


  where substances travel against a concentration gradient
• Plant roots are made of specialised “root hair cells”
• Root hair cells have a large surface area and a thin cell membrane to?


  help them take in water and nutrients
• Definition of specialised exchange surfaces ?


  the parts of an organism over which they exchange substances with their environment
• What 3 features do most exchange surfaces have in common

  • large surface area
  • thin exchange surfaces
  • surfaces are permable