Question

mini-quiz: substrate concentration and enzymes
based on your observations, how does substrate concentration affect enzyme activity?
i. there is more enzyme activity at higher substrate concentrations due to more collisions between enzyme and substrate, until a maximum reaction rate is reached.
ii. once the maximum reaction rate for the enzyme is reached, the reaction rate levels off.
iii. the reaction rate will always increase if substrate concentration is increased.
a. ii and iii only
b. i, ii and iii
c. i and iii only
d. i and ii only

Explanation:

• Analyze Statement I: Higher substrate concentration means more enzyme - substrate collisions, so enzyme activity (reaction rate) increases until a maximum rate is reached. This is correct.
• Analyze Statement II: Once all enzyme active sites are occupied (maximum reaction rate reached), adding more substrate won't increase the reaction rate, so the rate levels off. This is correct.
• Analyze Statement III: The reaction rate does not always increase with substrate concentration. After reaching the maximum rate (when enzymes are saturated), the rate stays constant. So this statement is incorrect.

So only Statements I and II are correct.

Answer:

D. I and II only