Transport in cells (B.19)

• substances moving from a high concentration to a low concentration is called

  diffusion
• two examples of diffusion in humans are:

  Co2 + O2 in gas exchange, urea from cells to blood
• three factors that affect the rate of diffusion are:

  concentration gradient, temperature, surface area of the membrane
• how are single celled organisms adapted for diffusion ?

  large surface area: volume ratio
• how is the small intestine adapted for exchanging materials?

  *Villi for large S.A(surface area to volume ratio) *villi one cell thick *good blood supply
• how is the lungs adapted for exchanging materials?

  Alveoli large surface area: volume ratio, surface is moist, good blood supply
• how is the gills adapted for exchanging materials?


  *large surface (surface area to volume ratio) *moist * good blood flow to maintain concentration gradient
• how is the roots adapted for exchanging materials?



  *large(surface area to volume ratio) *lots of mitochondria for respiration -> energy for active transport
• how is the leaves adapted for exchanging materials?

  *stomata *thin so that distance for diffusion is smaller
• Four ways that to increase the rate of transport

  1)Large surface area 2)thin membrane 3) efficient blood supply(in animals) 4)well ventilated(in animals)
• water moves from a dilute to concentrated solution across a partially permeable membrane via...

  diffusion
• pure water will move into a potato because

  of osmosis
• (RP) How can you tell the concentration of sugar in a piece of potato?


  1)place into different concentrations of sugar solution. 2)Plot graph 3)find concentration where mass doesn't change
• when a substance moves against the concentration gradient, it is called

  Active Transport
• Active transport requires _____ from ______

  energy respiration