B3 - Active transport

B3 - Active transport

1. Root hairs are specialised for absorbing water and minerals

   • The cells on the surface of plant roots grow into long hairs which stick out into the soil. This gives the plant a big surface area for absorbing water and mineral ions from the soil. Most of the water and mineral ions get into a plant are absorbed by the root hair cells.

2. Root hairs take in minerals using active transport

   • The concentration of minerals is usually higher in the root hair cell than in the soil around it so normal diffusion doesn't explain how minerals are taken up.
     • Active transport allows the plant to absorb minerals from a very dilute solution, against a concentration gradient. This essential for growth. It needs energy for respiration to make it work.
       • This also happens in humans - taking glucose from the gut and from kidney tubules

3. Active transport is used in the gut when there is a low concentration of nutrients in the gut but a high concentration of nutrients in the blood

   • When there's a higher concentration of glucose and amino acids in the gut they diffuse naturally into the blood
     • But sometimes there's a lower concentration of nutrients in the gut than there is in the blood
       • This means the concentration gradient is the wrong way.