Question 1

Which component of an enzyme is responsible for its catalytic activity and is made solely of protein?

Accepted Answer

Apoenzyme

Question 2

A holoenzyme is best described as:

Accepted Answer

An enzyme with its co-factor bound, forming a complete, active enzyme

Question 3

Which of the following best describes the role of a co-factor in enzyme activity?

Accepted Answer

It is a non-protein component required for the enzyme's activity

Question 4

In an energy diagram of a chemical reaction, what does the difference between the energy of reactants and products represent?

Accepted Answer

Overall energy released or absorbed during the reaction

Question 5

Given two reactions on an energy diagram, one with a lower activation energy and one with a higher activation energy, which is most likely catalyzed by an enzyme?

Accepted Answer

The reaction with the lower activation energy

Question 6

What does the 'active site' of an enzyme refer to?

Accepted Answer

The region of the enzyme where the substrate binds and the reaction occurs

Question 7

During an enzyme-catalyzed reaction, which of the following best describes the sequence of events?

Accepted Answer

Substrate binds to the active site, enzyme undergoes conformational change, product is released

Question 8

If a reaction releases energy and the products have lower energy than the reactants, how is this reaction classified?

Accepted Answer

Exergonic

Question 9

Which of the following equations correctly represents the change in free energy ($$\Delta G) $$for a reaction?

Accepted Answer

$$\Delta G = G_{products} - G_{reactants}$$

Question 10

Which statement best explains how enzymes lower the activation energy of a reaction?

Accepted Answer

Enzymes provide an alternative pathway with a lower activation energy

Question 11

A patient is diagnosed with a metabolic disorder due to a missing co-factor. Which of the following is most likely affected?

Accepted Answer

The enzyme cannot form a functional holoenzyme

Question 12

Which of the following is NOT a function of the active site of an enzyme?

Accepted Answer

Binding the co-factor

Question 13

A scientist observes that the rate of a reaction increases dramatically in the presence of an enzyme. What is the most likely explanation?

Accepted Answer

The enzyme lowers the activation energy required for the reaction

Question 14

Which of the following best describes a conformational change in an enzyme?

Accepted Answer

A change in the enzyme's shape upon substrate binding, facilitating catalysis

Question 15

In a multi-step metabolic pathway, an enzyme requires a co-factor to function. If the co-factor is absent, what is the most likely outcome?

Accepted Answer

The enzyme will be inactive and the reaction will not proceed

Question 16

Which of the following is true regarding the difference between an apoenzyme and a holoenzyme?

Accepted Answer

Holoenzyme consists of the apoenzyme plus its co-factor

Question 17

A reaction catalyzed by an enzyme is shown to have a lower activation energy than the same reaction without the enzyme. Which equation best represents the activation energy ($$E_a) $$for the catalyzed reaction?

Accepted Answer

$$E_a$$^{enzyme}$$ \u003c E_a$$^{uncatalyzed}$$

Question 18

Which of the following scenarios best illustrates the concept of substrate specificity in enzymes?

Accepted Answer

An enzyme binds only a specific substrate at its active site

Question 19

If the overall energy released during a reaction is $$-50 kJ/$$mol, what does this indicate about the reaction?

Accepted Answer

The reaction is exergonic

Question 20

Which of the following best describes the relationship between substrate, active site, and product in an enzyme-catalyzed reaction?

Accepted Answer

The substrate binds to the active site, undergoes a conformational change, and is converted to product

Enzymes: Structure, Function, and Catalysis

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