Question 1

Which of the following best describes the Second Law of Thermodynamics as it applies to biological systems?

Accepted Answer

Entropy of the universe is increasing, meaning the capacity of a system to do work is always decreasing.

Question 2

A reaction has a negative $$\Delta G. $$Which of the following statements is TRUE about this reaction?

Accepted Answer

The reaction is exergonic and releases free energy.

Question 3

Which equation correctly relates enthalpy, free energy, entropy, and temperature in a biological system?

Accepted Answer

$$H = G + TS$$

Question 4

During ATP hydrolysis, which of the following changes occurs?

Accepted Answer

$$\Delta G is $$negative and $$\Delta S is $$positive.

Question 5

Which of the following is NOT a type of biological work?

Accepted Answer

Photosynthetic

Question 6

Why is the change in energy ($$\Delta H or$$ $$\Delta G) $$more relevant than the absolute energy in biological reactions?

Accepted Answer

Change in energy determines the direction and spontaneity of reactions.

Question 7

Which of the following best explains why enzymes are necessary for life?

Accepted Answer

They lower the activation energy, allowing reactions to occur at biologically relevant rates.

Question 8

A patient is given a drug that binds reversibly to the active site of an enzyme, preventing substrate binding. What type of inhibition is this?

Accepted Answer

Competitive inhibition

Question 9

Which of the following statements about enzyme-catalyzed reactions is CORRECT?

Accepted Answer

Enzymes speed up both the forward and reverse reactions.

Question 10

Which of the following is an example of feedback inhibition?

Accepted Answer

A product of a metabolic pathway inhibits the first enzyme in the pathway.

Question 11

Which of the following best describes the induced fit model of enzyme-substrate interaction?

Accepted Answer

The substrate induces a conformational change in the enzyme, optimizing binding and catalysis.

Question 12

A mutation causes an enzyme to lose its ability to bind its substrate. Which property is most likely affected?

Accepted Answer

The enzyme's active site conformation

Question 13

Which of the following is true about the Michaelis-Menten constant ($$K_m$$)?

Accepted Answer

$$K_m is $$the substrate concentration at which the reaction rate is half-maximal.

Question 14

Which of the following is a real-life example of irreversible enzyme inhibition?

Accepted Answer

Aspirin binding to prostaglandin synthetase

Question 15

Which of the following best explains why heat and extreme pH can denature proteins?

Accepted Answer

They disrupt hydrogen bonds, ionic bonds, and hydrophobic interactions stabilizing the protein's structure.

Question 16

Which of the following is NOT a method of enzyme regulation?

Accepted Answer

Substrate hydrolysis

Question 17

A patient with a genetic disorder lacks a functional enzyme required for a metabolic pathway. Which of the following is a likely consequence?

Accepted Answer

The substrate for the missing enzyme will accumulate.

Question 18

Which of the following statements about the effect of enzymes on activation energy and $$\Delta G is $$correct?

Accepted Answer

Enzymes lower the activation energy but do not change the $$\Delta G.$$

Question 19

Which of the following is an example of allosteric regulation?

Accepted Answer

A molecule binds to a site other than the active site, changing enzyme activity.

Bioenergetics and Enzyme Catalysis in Cell Biology

Study Guide - Practice Questions