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. i and ii only
b. i, ii and iii
c. i and iii only
d. ii and iii only

Explanation:

Enzymes are biological catalysts. When substrate concentration increases, more enzyme - substrate collisions occur, increasing enzyme activity until all enzyme active sites are saturated (maximum reaction rate). After that, adding more substrate won't increase the reaction rate as enzymes are already working at full capacity. So statement III is incorrect as the reaction rate doesn't always increase with substrate concentration. Statements I and II are correct.

Answer:

A. I and II only