transport in cells

• diffusion is the net movement of particles from an area of high concentration to an area of low concentration.
• give an example of a place where diffusion happens in our body

  in the small intestine in the vilis
• • factors that increase the rate of diffusion are: increased surface area, increased concentration gradient, increased temperature, increased blood flow
• examples of diffusion

  • gas exchange in the alveoli
  • absorption of glucose in the small intestine
  • excretion of urea in the kidneys
• villi

  • verry large surface area (surface area to volume ratio)
  • one cell thick (makes diffusion easier)
  • high blood flow (increase concentration)
• • alveoli
  • have a large surface area
  • thin walls
  • lots of blood capillaries
• root hair cell

  • large surface area (finger like structure)
  • large number of mitochondria
  • large vacuole
• where are villi found

  they are lined within the small intestine
• osmosis is the movement of water from a dilute solution to a more concentrated solution across a partially permeable membrane.
• active transport is when substances move from a more dilute solution to a more concentrated solution against the concentration gradient
• what does it mean to go against the concentration gradient

  to go to an area of low concentration to an area of high concentration
• how does active transport go against the concentration gradient


  it uses energy from respiration
• difference between diffusion, osmosis from active transport

  • active transport uses energy
  • active transport goes against the concentration gradient