Which enzyme works at an optimum pH of about 2?
Correct answer: B. Pepsin
- A. Salivary amylase
- B. Pepsin
- C. Trypsin
- D. Catalase
Explanation
Pepsin is secreted into the stomach where hydrochloric acid keeps the pH near 2, and its structure is stable and active in exactly those conditions. Trypsin works in the small intestine at about pH 8, salivary amylase near neutral, and catalase around pH 7. An enzyme moved far from its optimum pH loses activity because the charges on the R groups in the active site change.
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About Factors Affecting Enzyme Action
Enzyme activity changes with temperature, pH, substrate concentration and enzyme concentration because these factors affect molecular collisions and the active site. Questions also examine optimum conditions, denaturation and inhibition, while distinguishing a fall in activity caused by unsuitable conditions from permanent enzyme damage.
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