Active Transport

• Sometimes substances need to be absorbed against a concentration gradient i.e. from a lower to a higher concentration, also known as Active Transport.
• Each branch of a root hair cell is covered in millions of microscopic hairs
• The millions of hair give a large surface area for absorbing water and mineral ions from the soil
• Plants need mineral ions for healthy growth
• The concentration of minerals is usually higher in the root hair cells than the soil around them, so the root hair cells can't use diffusion to take up minerals from the soil
• Minerals should move out of the root hairs if they followed the rules of diffusion. the cells must use another method to draw them in
• Active Transport allows the plant to absorb the minerals from a very dilute solution,against a concentration gradient. But Active transport needs energy from respiration to make it work
• Active transport needs energy from respiration to make it work
• Active transport also happens in humans,for example in taking glucose from the gut and from the kidney tubes
• We need active transport to stop us starving
• Active transport is used in the gut when there is a lower concentration of nutrients in the gut,but a higher 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
• Sometimes there's a lower concentration of nutrients in the gut then there is in the blood,this means the concentration gradient is the wrong way
• Active Transport allows nutrients to be taken into the blood,despite the concentration gradient being the wrong way. This means that glucose can be taken into the bloodstream even when the concentration of blood is already higher than the gut. It can be transported to cells and used for respiration