Digestion 01

This KS3 Science quiz asks questions about digestion. Digestion is the breaking down of food from being large insoluble molecules into smaller soluble molecules. These smaller molecules can then be absorbed through the lining of the small intestine and dissolved into the blood plasma. The process of digestion begins in the mouth. Chewing breaks down food into smaller lumps and saliva is mixed with the crushed food. Saliva contains an enzyme called amylase. This starts to break down the starches in the food into glucose. Glucose is needed by cells to release energy.

Digestion of proteins starts in the stomach and is completed in the small intestine. The enzyme called protease breaks proteins down into amino acids. These are used by your body for growth and repair.

Fats and oils like butter or olive oil are broken down in the small intestine by a group of enzymes called lipases. As the liquid from the stomach enters the small intestine, bile is added. This emulsifies the fats and oils into small globules which makes it easier for the lipases to digest them. Dietary fibre is mainly cellulose - humans don't have any means of digesting it so it passes through the digestive system.