Active Transport

• Active Transport


  Process where substances need to be absorbed against a concentration gradient, i.e. from a lower to a higher concentration
• Root Hair Cells


  • Grow on plant roots and stick out into the soil
  • Give the plant a large surface area for absorbing water and mineral ions from the soil
  • Concentration of minerals is usually higher in the root hair cells than in the soil around them, so they can't use diffusion to take up minerals
• Root Hairs Take in Minerals Using Active Transport

  1. Minerals should move out of the root hairs if they followed the rules of diffusion

  2. Root hair cells use active transport to absorb minerals from a very dilute solution, against a concentration gradient

  3. Active transport needs energy from respiration to make it work

  4. Active transport also happens in humans, for example in taking glucose from the gut and from the kidney tubules
• When there's a higher concentration of nutrients in the gut


  They diffuse naturally into the blood
• When there's a lower concentration of nutrients in the gut than there is in the blood


  The concentration gradient is the wrong way, so active transport is used to take nutrients into the blood
• Active transport allows nutrients to be taken into the blood, despite the fact that the concentration gradient is the wrong way
• Active transport allows glucose to be taken into the bloodstream when its concentration in the blood is already higher than in the gut, so it can then be transported to cells and used for respiration