Free Factors Affecting Enzyme Action MCQs with Answers
13 Factors Affecting Enzyme Action MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
13 questions · page 2 of 2
11. Which factor does NOT affect enzyme activity?
- A. Temperature
- B. pH
- C. Substrate concentration
- D. Color of the solution
Explanation: Enzyme activity is affected by temperature, pH, substrate concentration, and presence of inhibitors/activators, but not by color.
Correct answer: Color of the solution12. Enzymes activity decreases at very low or high pH because:
- A. Substrate concentration increases
- B. Enzymes become denatured
- C. Product formation increases
- D. Temperature becomes constant
Explanation: Excess hydrogen or hydroxide ions disturb the ionic and hydrogen bonds between the side chains that hold the tertiary structure, so the active site loses its precise shape and the substrate no longer fits. A small shift is reversible, but an extreme one denatures the enzyme permanently. This is why pepsin works at about pH 2 and trypsin at about pH 8, each being inactive in the other's conditions.
Correct answer: Enzymes become denatured13. Effect of increased substrate concentration on enzyme activity:
- A. Decrease the rate of reaction
- B. Increase the reaction rate until all active sites are saturated
- C. Have no effect on the reaction rate
- D. Increase the rate of reaction in a straight diagonal line
Explanation: Rate rises steeply at first because more collisions occur between substrate and free active sites, then levels off at Vmax once every site is occupied and the enzyme is working as fast as it can. The curve is therefore hyperbolic rather than a straight line, which is what the fourth option gets wrong. Beyond saturation the enzyme concentration rather than the substrate is limiting.
Correct answer: Increase the reaction rate until all active sites are saturated