Question 1

Which of the following best describes the difference between catabolic and anabolic pathways in cellular metabolism?

Accepted Answer

Catabolic pathways break down molecules to release energy, while anabolic pathways use energy to build complex molecules from simpler ones.

Question 2

Which of the following is an example of chemical work performed by a cell?

Accepted Answer

Synthesizing a protein from amino acids.

Question 3

A chemical reaction has a $$\Delta G of$$ $$-15 kJ/$$mol. Which of the following statements is true about this reaction?

Accepted Answer

The reaction is exergonic and spontaneous.

Question 4

Which of the following best explains how ATP hydrolysis powers endergonic reactions in cells?

Accepted Answer

ATP hydrolysis releases energy that is used to phosphorylate a reactant, making the overall coupled reaction exergonic.

Question 5

Which of the following equations correctly represents the hydrolysis of ATP?

Accepted Answer

$$\mathrm{ATP} + \mathrm{H}_2\mathrm{O} \rightarrow \mathrm{ADP} + \mathrm{P}_i$$

Question 6

If a cell is placed in an environment where $$\Delta G = 0$$ for all its chemical reactions, what would happen?

Accepted Answer

The cell would be unable to do work and would eventually die.

Question 7

Which of the following best describes the role of enzymes in biological systems?

Accepted Answer

Enzymes lower the activation energy ($$E_a) $$required for a reaction to proceed.

Question 8

A scientist increases the temperature of an enzyme-catalyzed reaction. Which of the following is most likely to occur if the temperature exceeds the enzyme's optimal range?

Accepted Answer

The enzyme will denature, causing the reaction rate to decrease.

Question 9

Which of the following statements about enzyme specificity is correct?

Accepted Answer

Enzymes are specific because their active sites fit only certain substrates.

Question 10

Which of the following best describes the effect of a competitive inhibitor on an enzyme-catalyzed reaction?

Accepted Answer

It binds to the enzyme's active site, blocking substrate binding.

Question 11

Which of the following is NOT a type of energy relevant to biological systems?

Accepted Answer

Nuclear energy

Question 12

Which of the following statements about the relationship between $$\Delta G$$ and stability is correct?

Accepted Answer

Systems with a low $$\Delta G$$ are more stable than those with a high $$\Delta G.$$

Question 13

During photosynthesis, plants convert water and carbon dioxide into glucose. This process is an example of which type of reaction?

Accepted Answer

Endergonic reaction

Question 14

Which of the following best explains why enzymes are not used up during the reactions they catalyze?

Accepted Answer

Enzymes are regenerated after each reaction and can catalyze multiple cycles.

Question 15

A cell needs to drive an endergonic reaction with $$\Delta G = +10 kJ/$$mol. If ATP hydrolysis provides $$-30 kJ/$$mol, what is the net $$\Delta G$$ for the coupled reaction?

Accepted Answer

$$-20 kJ/$$mol

Question 16

Which of the following factors does NOT directly affect enzyme activity?

Accepted Answer

Atmospheric pressure

Question 17

Which of the following best describes the effect of increasing substrate concentration on the rate of an enzyme-catalyzed reaction, assuming enzyme concentration is constant?

Accepted Answer

The reaction rate will increase and then level off when the enzyme becomes saturated.

Question 18

Which of the following is a real-world example of mechanical work performed by a cell?

Accepted Answer

Contracting muscle fibers to produce movement.

Question 19

Which of the following statements about equilibrium in a chemical reaction is correct?

Accepted Answer

At equilibrium, the forward and reverse reaction rates are equal.

M7-Metabolism, Energy, and Enzymes: Foundations of Cellular Processes

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