cell transport

• what is diffusion?

  the movement of particles from a high concentration to a low concentration
• what substances in animals and plants are transported by diffusion?

  oxygen , carbon dioxide and urea
• how does a difference in concentration affect diffusion?

  increased concentration gradient = faster diffusion
• how does temperature affect the rate of diffusion?

  increased temperature means a higher rate of diffusion due to the particles having more kinetic energy to move faster.
• how does surface area affect diffusion?

  increased surface area = increased rate of diffusion because the amount of the substance or substances is increased
• how are single cell organisms adapted for diffusion?

  have a large surface area to volume ratio
• how is the small intestine adapted for diffusion?

  long and has villi for a large surface area.

  cell membranes are thin making a short diffusion pathway

  good blood supply

  steep concentration gradient

  lots of mitochondria for energy
• How are lungs adapted for gas exchange?

  lots of alveoli for a large surface area

  thin for a short diffusion pathway

  good ventilation and blood supply in order to maintain a steep concentration gradient
• how are gills adapted for exchange?

  large surface area

  thin for a short diffusion pathway

  good ventilation and blood supply to maintain a steep concentration gradient
• How are leaves adapted for gas exchange?

  large surface area

  small diffusion pathway
• how are roots adapted for exchange?


  large surface area

  thin membrane so short diffusion pathway

  lots of mitochondria for active transport
• what is osmosis?

  the movement of particles from a high concentration to a low concentration through a partially permeable membrane
• what is active transport ?

  the movement of particles from a low concentration to a high concentration essentially going against the concentration gradient. the process requiring energy!
• what is an example of active transport in animals ?


  absorption of sugar in the gut from low to high
• what is an example in mineral ions ?

  absorption of mineral ions into the plant root hairs