Question 1

Which of the following best describes how enzymes affect the activation energy of a chemical reaction?

Accepted Answer

Enzymes lower the activation energy, allowing reactions to proceed more quickly.

Question 2

During the hydrolysis of lactose, which of the following best represents the chemical reaction?

Accepted Answer

$$\mathrm{lactose} + \mathrm{H}_2\mathrm{O} \rightarrow \mathrm{glucose} + \mathrm{galactose}$$

Question 3

A scientist measures the rate of an enzyme-catalyzed reaction by tracking product formation over time. The rate is highest at the beginning and then levels off. What is the most likely explanation for this pattern?

Accepted Answer

The substrate concentration decreases as it is converted to product, slowing the reaction.

Question 4

Which of the following statements about enzyme specificity is correct?

Accepted Answer

Enzyme specificity is determined by the shape of the active site and its compatibility with the substrate.

Question 5

If the temperature of an enzyme-catalyzed reaction is increased beyond the enzyme's optimal range, what is the most likely effect on the enzyme's structure and function?

Accepted Answer

The enzyme will denature, losing its secondary and tertiary structure, and its activity will decrease.

Question 6

Which of the following best explains why enzymes are not considered reactants in the reactions they catalyze?

Accepted Answer

Enzymes are not changed by the reaction and can be reused.

Question 7

A competitive inhibitor affects an enzyme-catalyzed reaction by:

Accepted Answer

Binding to the active site, preventing the substrate from binding.

Question 8

Which of the following graphs best represents the effect of an enzyme on the activation energy of a reaction?

Accepted Answer

A graph where the activation energy peak is lower with the enzyme present.

Question 9

Which of the following is true regarding the relationship between substrate concentration and enzyme activity?

Accepted Answer

Enzyme activity increases with substrate concentration until the enzyme is saturated, after which it levels off.

Question 10

In a metabolic pathway, feedback inhibition is best described as:

Accepted Answer

The final product of the pathway acts as an allosteric inhibitor of an earlier enzyme.

Question 11

Which of the following best explains why living organisms require a constant input of energy?

Accepted Answer

To maintain order and counteract the natural tendency toward increased entropy.

Question 12

Which of the following is an example of an exergonic reaction in cellular metabolism?

Accepted Answer

The breakdown of ATP to ADP and inorganic phosphate ($$\mathrm{ATP} \rightarrow \mathrm{ADP} + \mathrm{P_i}).$$

Question 13

Which of the following statements about the active site of an enzyme is correct?

Accepted Answer

The active site is flexible and can change conformation when the substrate binds.

Question 14

A mutation changes the amino acid sequence of an enzyme's active site. What is the most likely consequence?

Accepted Answer

The enzyme may lose its ability to bind its specific substrate, reducing or eliminating its activity.

Question 15

Which of the following best describes the induced fit model of enzyme function?

Accepted Answer

The enzyme changes its conformation slightly when the substrate binds, enhancing catalysis.

Cellular Energetics and Enzyme Function: Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard