Active transport

• Three processes contribute to the movement of substances into and out of cells: diffusion, osmosis and active transport.
• Diffusion is a process that mixes particles.
• Osmosis is a process that affects plant tissue.
• Active transport is a process that moves substances against a concentration gradient.
• In plants, mineral ions are moved into root hairs, where they are in a higher concentration than in the dilute solutions in the soil.
• Active transport then occurs across the root so that the plant takes in the ions it needs from the soil around it.
• In animals, glucose molecules have to be moved across the gut wall into the blood.
• The glucose molecules in the intestine might be in a higher concentration than in the intestinal cells and blood, for instance, after a sugary meal, but there will be times when glucose concentration in the intestine might be lower.
• All the glucose in the gut needs to be absorbed.
• When the glucose concentration in the intestine is lower than in the intestinal cells, movement of glucose involves active transport.
• The process of active transport requires energy produced by respiration.