BECE JHS
Digestion breaks large food molecules into smaller ones the blood can absorb.
Digestion starts in the mouth. Teeth cut and grind the food, and saliva wets it. Saliva contains amylase, which begins changing starch into sugar. The tongue rolls the food into a bolus and you swallow. The food moves down the oesophagus by peristalsis, a wave of muscle contraction. It is not digested there.
In the stomach, churning mixes the food with gastric juice. Hydrochloric acid gives a low pH so that pepsin, a protease, can work on protein, and it kills many germs. Most digestion and almost all absorption happen in the small intestine. Enzymes from the pancreas and the intestinal wall finish the work. Bile from the liver, stored in the gall bladder, breaks fat into tiny droplets. It is not an enzyme. Villi give a large surface for absorption. The large intestine absorbs water, and the rectum stores the waste.
Name the part and the job, not a list of organs with no function. Say what an enzyme acts on and what it produces. Bile emulsifies fat. It does not digest fat. Absorption of digested food is the small intestine. Absorption of water is the large intestine. Do not swap them.
These are practice questions in the style of the paper, with a model answer and a mark scheme. They are not a promise of what your paper will ask.
4 marks
(a) What is digestion? (2 marks)
(b) Name the enzyme in saliva and the food substance it acts on. (2 marks)
(a) Digestion is the breakdown of large, insoluble food molecules into smaller, soluble ones that can be absorbed.
(b) Amylase acts on starch.
5 marks
(a) State two roles of hydrochloric acid in the stomach. (2 marks)
(b) Explain why bile is not called an enzyme. (2 marks)
(c) Name the part of the gut where most digested food is absorbed. (1 mark)
(a) It gives the acid pH that pepsin needs, and it kills many germs.
(b) Bile only breaks fat into small droplets. It is not a protein catalyst, and it does not change fat into a new substance.
(c) The small intestine.
4 marks
A student wrote: "The large intestine digests food and the stomach absorbs it." Correct the two mistakes. (4 marks)
The stomach digests, it does not absorb digested food. Protein digestion begins there. The large intestine does not digest food. It absorbs water.
More questions on this topic are inside GLearn, marked as you answer, with the reason written out. The first ones need no account.
Practise Science freeNo. Bile emulsifies fat, which means it splits large fat drops into tiny droplets so lipase can work faster. Lipase is the enzyme that digests fat. Bile is made in the liver and stored in the gall bladder.
In the small intestine. Villi and microvilli give a very large surface, and each villus has a blood capillary and a lacteal. The large intestine absorbs water, not the digested food. All BECE Science past questions