Question

1.   Which of the following is true of enzyme catalyzed reactions?

a.   Reaction rates are temperature dependent

b.   Reaction rates are pH dependent

c.   Reaction rates depend on substrate concentration

d.   Reaction rates depend on enzyme structure

e.   All of the above

f.    a, b, and c

2.   Which of the following is NOT true of enzymes?

a.   Enzyme activity depends on reaction conditions.

b.   Enzymes are catalysts that decrease the rate of reaction.

c.   Enzymes can be inhibited by other proteins

d.   Enzymes do not alter the change in free energy (ΔG) of the reaction.

3.   For a given reaction involving an enzyme, competitive inhibitors will cause Vmax to (increase/decrease/stay the same), while causing Km to (increase/decrease/stay the same).

4.   Below the optimal temperature, increasing the temperature of an enzyme-catalyzed reaction will (increase/decrease/not change) its reaction rate, whereas above the optimal temperature, an increase in temperature will (increase/decrease/not change) the reaction rate.

Answer 1

1. Answer: Option E is correct
Explanation:
Reatction rate of an enzyme catalyzed reaction is dependent on several factors
i. Temperature
ii. pH
iii. Substrate concnetration
iv. Presence of activators or inhibitors that alter the enzyme structure and its affinity for the substrate

2. Answer: Option B is correct
Explanation:
Enzymes are biocatalysts that increase the rate of reactions by multiple mechanisms
i. By decreasing the activation energy
ii. By increasing the effective concnetrations of substrates

3. A competitive inhibitor resembles the structure of the substrate and competes for the same active site on the enzyme
It increases the Km but does not affect Vmax.

4. Any deviation (increase or decrease) in temperature from the optimal range decreases the reaction rate.