Question

mini - quiz: substrate concentration and enzymes
how is enzyme activity at varying substrate concentrations different from enzyme activity at varying temperatures or ph levels?
i. the graph for substrate concentration shows the rate levelling off when substrate concentration is high, instead of declining when not in the optimal range.
ii. when increasing substrate concentration, it is apparent that the enzyme denatures but this is not seen when increasing temperature or ph.
iii. changes in substrate concentration do not cause the enzyme to denature, but changes in temperature and ph may cause the enzyme to denature.
a. ii and iii only
b. i, ii and iii
c. i and iii only
d. iii only

Explanation:

• For I: As substrate concentration increases, enzyme - substrate complexes form. At high substrate concentrations, all enzyme active sites are saturated, and the reaction rate levels off. In contrast, for temperature and pH, outside the optimal range, the rate declines due to enzyme denaturation.
• For II: Increasing substrate concentration does not denature the enzyme. Increasing temperature or pH outside the optimal range can denature the enzyme.
• For III: Changes in substrate concentration do not cause denaturation, while extreme changes in temperature and pH can denature the enzyme.

Answer:

C. I and III only