Question 1

Which of the following best describes the difference between potential energy and kinetic energy in biological systems?

Accepted Answer

Potential energy is stored due to an object's position or structure, such as in chemical bonds, while kinetic energy is associated with the movement of objects or molecules.

Question 2

A diver standing on a diving board has more potential energy than after jumping into the water. What law of thermodynamics explains that the total energy before and after the dive remains the same?

Accepted Answer

The first law of thermodynamics

Question 3

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

Accepted Answer

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

Question 4

A reaction has a $$ \Delta G  of$$ $$ -5.6 $$ kcal/mol. Which of the following statements is most likely true?

Accepted Answer

The reaction is exergonic and can occur spontaneously.

Question 5

ATP hydrolysis releases energy that can be used to drive endergonic reactions in cells. Which of the following best explains why ATP hydrolysis is so exergonic?

Accepted Answer

The free energy of the bond between phosphate groups in ATP is much higher than the energy of the O-H bond that forms after hydrolysis.

Question 6

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

Accepted Answer

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

Question 7

A certain enzyme works best at pH 2. What would most likely happen to the enzyme's activity if the pH is increased to 8?

Accepted Answer

The enzyme would denature, losing its functional shape and activity.

Question 8

Which of the following is an example of allosteric regulation of an enzyme?

Accepted Answer

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

Question 9

In a metabolic pathway, the end product inhibits an enzyme that acts early in the pathway. This is an example of:

Accepted Answer

Feedback inhibition

Question 10

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

Accepted Answer

Every energy transfer increases the entropy (disorder) of the universe.

Question 11

A reaction in a cell has a $$ \Delta G  of$$ $$ +3.4 $$ kcal/mol. Which of the following is true about this reaction?

Accepted Answer

It is endergonic and requires an input of energy.

Question 12

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

Accepted Answer

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

Question 13

Which of the following scenarios best illustrates the coupling of exergonic and endergonic reactions in a cell?

Accepted Answer

The hydrolysis of ATP releases energy that is used to drive the synthesis of glucose from carbon dioxide and water.

Question 14

Which of the following is NOT a way that enzymes lower the activation energy of a reaction?

Accepted Answer

Increasing the $$ \Delta G  of $$the reaction.

Question 15

A patient is diagnosed with a genetic disorder that causes a key metabolic enzyme to be nonfunctional. Which of the following is the most likely consequence?

Accepted Answer

The pathway will be blocked at the step catalyzed by the nonfunctional enzyme, leading to accumulation of the substrate.

Question 16

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

Accepted Answer

It binds to the active site, preventing the substrate from binding.

Question 17

If the hydrolysis of ATP to ADP and $$ P_i $$ has a $$ \Delta G  of$$ $$ -7.3 $$ kcal/mol, what is the maximum $$ \Delta G  of an $$endergonic reaction that can be powered by the hydrolysis of one mole of ATP?

Accepted Answer

$$ +7.3 $$ kcal/mol

Question 18

Which of the following is a real-life example of the conversion of potential energy to kinetic energy?

Accepted Answer

A stretched bowstring being released to launch an arrow.

Question 19

Which of the following statements about denaturation of enzymes is correct?

Accepted Answer

Denaturation involves the loss of quaternary, tertiary, and secondary structure, leading to loss of function.

Energy, Enzymes, and an Introduction to Metabolism

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