Question 1

Which of the following best describes an exergonic reaction in terms of free energy ($$\Delta G) $$and spontaneity?

Accepted Answer

It has a negative $$\Delta G$$ and is spontaneous.

Question 2

A patient is given a drug that acts as a noncompetitive inhibitor for a key metabolic enzyme. Which of the following best describes how this drug affects the enzyme?

Accepted Answer

It binds to a site other than the active site, changing the enzyme's shape and reducing activity.

Question 3

Which of the following is an example of an anabolic pathway?

Accepted Answer

Photosynthesis

Question 4

According to the first law of thermodynamics, which of the following statements is true?

Accepted Answer

Energy can be transferred and transformed, but not created or destroyed.

Question 5

A scientist measures the $$\Delta G$$ for the hydrolysis of ATP as $$-7.3$$ kcal/mol. What does this value indicate about the reaction?

Accepted Answer

The reaction is exergonic and releases energy.

Question 6

Which of the following best explains why enzymes are highly specific for their substrates?

Accepted Answer

The active site of an enzyme has a unique shape that fits only specific substrates.

Question 7

A metabolic pathway is regulated by feedback inhibition. Which of the following best describes this process?

Accepted Answer

The end product of the pathway inhibits an earlier enzyme, shutting down the pathway.

Question 8

Which of the following is NOT a function of enzymes in biological systems?

Accepted Answer

Changing the overall free energy change ($$\Delta G) of a $$reaction

Question 9

During the conversion of glutamic acid to glutamine, the reaction has a $$\Delta G = +3.4$$ kcal/mol. How does the cell make this reaction proceed?

Accepted Answer

By coupling it with the hydrolysis of ATP, which has a $$\Delta G = -7.3$$ kcal/mol

Question 10

Which of the following statements about the second law of thermodynamics is correct?

Accepted Answer

Every energy transfer or transformation increases the entropy of the universe.

Question 11

A cell is performing active transport of ions across its membrane. Which molecule is most directly providing the energy for this process?

Accepted Answer

ATP

Question 12

Which of the following best describes the role of cofactors in enzyme activity?

Accepted Answer

Cofactors are non-protein helpers that may be inorganic ions or organic molecules.

Question 13

A researcher finds that an enzyme works best at pH 2 and loses activity at pH 7. Where in the human body is this enzyme most likely to be found?

Accepted Answer

In the stomach

Question 14

Which of the following scenarios illustrates energy coupling in a cell?

Accepted Answer

The hydrolysis of ATP releases energy that is used to drive an endergonic reaction.

Question 15

Which of the following statements about the localization of enzymes in eukaryotic cells is correct?

Accepted Answer

Some enzymes are embedded in membranes or located within specific organelles.

Question 16

A mutation causes an enzyme to lose its ability to change shape when binding its substrate. Which property of enzyme function is most directly affected?

Accepted Answer

Induced fit

Question 17

Which of the following best explains why heat can denature enzymes?

Accepted Answer

Heat disrupts the three-dimensional structure of proteins, altering the active site.

Question 18

Which of the following is a correct example of a catabolic pathway?

Accepted Answer

Cellular respiration

Question 19

A cell is at equilibrium with respect to a particular metabolic reaction. What can be said about the free energy change ($$\Delta G) $$and the ability to do work?

Accepted Answer

$$\Delta G is $$zero and no work can be done by the reaction.

Question 20

Which of the following is a real-life example of feedback inhibition in human metabolism?

Accepted Answer

The end product isoleucine inhibits the first enzyme in its biosynthetic pathway.

Energy and Metabolism: Foundations of Biology Study Notes

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