Explain the role of each of the following components of gastric juice in food digestion: (a) Pepsin; (2 marks) (b) Hydrochloric acid. (2 marks)June/July 2020

(a) Pepsin is an enzyme found in the gastric juice of the stomach. It plays a key role in the digestion of proteins by breaking them down into smaller peptides and amino acids. Pepsin works by breaking the bonds between the amino acids that make up proteins. It is most effective at breaking down proteins when the pH of the stomach is low, which is maintained by the presence of hydrochloric acid.

(b) Hydrochloric acid is a component of gastric juice that is produced by the cells lining the stomach. It plays a number of important roles in the digestive process, including maintaining the low pH of the stomach, which is necessary for the activation of pepsin and other digestive enzymes. Hydrochloric acid also helps to kill bacteria that may be present in the food we eat, which helps to prevent foodborne illness. Additionally, hydrochloric acid helps to break down the tough, fibrous tissues found in some types of food.