Active Transport

• Sometimes substances need to be absorbed against a concentration gradient.
• • the cells on plant roots grow into hairs which stick out into the soil
  • each branch of a root will be covered in millions of microscopic hairs
  • this gives the plant a large surface area for absorbing water and mineral ions from the soil
  • plants need these mineral ions for healthy growth
  • the concentration of minerals is higher in the root hair cells than in the soil around them
  • so the root hair cells can't use diffusion to take up minerals from the soil.
• Root hairs take in minerals using active transport

  • Minerals should move out of the root hairs if they followed the rules of diffusion.
  • They use active transport to absorb minerals.
  • This allows the plant to absorb minerals from a very dilute solution, against the concentration gradient. However, active transport requires energy from respiration to work.
  • Active transport also happens in humans, for example taking in glucose from the gut and kidney tubules.
• Active transport is used in the gut when there is a lower concentration of nutrients in the gut, but a higher concentration in the blood.
• • When there's a higher concentration of glucose and amino acids they diffuse naturally into the blood.
  • But- sometimes there is a lower concentration of nutrients in the gut than there is in the blood
  • The body must use active transport
  • The active transport allows nutrients to be taken into the blood against the concentration gradient.
• Active transport uses energy