Quiz: Digestive System: Enzymes and Absorption — 3 questions

1. What is one important effect of hydrochloric acid in the stomach that also helps pepsin work effectively?

A. It raises the pH so pepsin can function in the intestine

B. It neutralises the stomach contents so pepsin becomes inactive

C. It creates a very low pH that kills harmful microbes and helps set the optimum pH for pepsin

D. It breaks proteins directly into amino acids without enzymes

Answer: (C)

Explanation

Hydrochloric acid makes the stomach highly acidic, which helps denature harmful microorganisms and provides the optimum pH for pepsin activity. Pepsin depends on this acidic environment to work well.

2. What is the primary role of hydrochloric acid in gastric juice?

A. To increase the pH of food in the stomach for enzyme function.

B. To create a low pH environment that denatures harmful microorganisms and primes pepsin activity.

C. To neutralise stomach acid entering the small intestine.

D. To directly digest proteins in food.

Answer: (B)

Explanation

Hydrochloric acid creates a low pH that denatures microbes and provides the optimum environment for pepsin to work effectively, which is essential for protein digestion in the stomach.

3. Which statement best describes enzymes in digestion?

A. They are physical processes that break food into smaller pieces

B. They are carbohydrates that store energy for digestion

C. They are organs that absorb digested food into the body

D. They are proteins that act as biological catalysts and are not changed by the reaction

Answer: (D)

Explanation

Enzymes are protein catalysts that speed up chemical reactions without being consumed. Mechanical digestion is the physical breakdown of food, not an enzyme process.