Final answer:
Doubling the enzyme concentration will double the Vmax but not alter the Km, which is intrinsic to the enzyme's affinity for the substrate. The correct answer is option a.
Step-by-step explanation:
When considering the effect of doubling the concentration of an enzyme on Vmax (maximum velocity) and Km (Michaelis-Menten constant), it's important to understand the kinetics of enzyme-catalyzed reactions. The Vmax reflects the maximum rate of the reaction when the enzyme's active sites are fully occupied by the substrate. In contrast, Km reflects the substrate concentration at which the reaction rate is half of Vmax.
Doubling the enzyme concentration will increase the Vmax since there are more active sites available for the reaction to occur at any given time; however, it will not alter the Km because Km is an intrinsic characteristic of the enzyme's affinity for the substrate, which is not affected by enzyme concentration. Therefore, the correct answer is option 1) double, not alter. This means that when the concentration of the enzyme is doubled, the Vmax is expected to double, but the Km will remain the same.
Note that enzyme kinetics can be more complex if allosteric effects or cooperative binding is involved, but for standard Michaelis-Menten kinetics, these are the expected outcomes. Always consider the context and specific mechanism of the enzyme when analyzing such questions.