Question 1
Which of the following statements about enzyme-catalyzed reactions is true?
a. Enzymes always drive reactions toward chemical equilibrium.
b. The free-energy change of the reaction is greater than when the same reaction occurs in the absence of an enzyme.
c. The rate of the reaction is greater than when the same reaction occurs in the absence of an enzyme.
d. Energy from ATP is required to activate the enzyme before it can catalyze the reaction.
Question 2
Which Of The Following Statements Is False About Enzymes?
Question 3
Which of the following is true of enzymes?
A. Enzymes increase the rate of chemical reaction by lowering activation energy barriers.
B. Enzyme function is increased if the 3-D structure or conformation of an enzyme is altered.
C. Enzyme function is independent of physical and chemical environmental factors such as pH and temperature.
D. Nonprotein cofactors alter the substrate specificity of enzymes.
Answer to question 1
The correct option is c. The rate of the reaction is greater than when the same reaction occurs in the absence of an enzyme.
An enzyme is often referred to as a biocatalyst as these proteinaceous molecules help in increasing the speed at which any biochemical reaction takes place. These molecules function by targeting the activation energy of reactions and lowering it. This helps in directing the chemical reaction in a forward direction so that the desired final product is obtained rapidly.
Please note that:
- Option a. is incorrect because molecules of enzymes drive any biochemical reaction towards the product’s side, that is, in the forward direction.
- Option b. is incorrect because the free-energy change of a biochemical reaction is less in the presence of enzyme as compared with the free-energy change value in the absence of enzyme.
- Option d. is incorrect because activation of enzymatic molecules does not require the expenditure of ATP.
Answer to question 2
Ans: Enzymes are equally active at all pH and temperature ranges.
No the enzymes are not active at all pH and temperature ranges. Infact the change in pH and temperature conditions may cause the enzyme to become denatured and hence become inactive and inefficient to perform its function in catalysing the boichemical reactions in the body.
Answer to question 3
