Q: A reaction has $\Delta H = -20$ kJ/mol and $\Delta S = 0.05$ kJ/(mol\cdot K). At $T = 300$ K, what is $\Delta G$ for the reaction?

$\Delta G = -20 - (300 \times 0.05) = -35$ kJ/mol

Question 1

Which statement best describes the First Law of Thermodynamics as it applies to biological systems?

Accepted Answer

Energy cannot be created or destroyed, only transformed from one form to another.

Question 2

A cell performs an endergonic reaction by coupling it to the hydrolysis of ATP. Which equation correctly represents the change in free energy ($\Delta G$) for the coupled reaction?

Accepted Answer

$\Delta G_{coupled} = \Delta G_{endergonic} + \Delta G_{ATP hydrolysis}$

Question 3

Which of the following best explains why only reactions with a negative $\Delta G$ are spontaneous?

Accepted Answer

A negative $\Delta G$ indicates that the reaction releases free energy, making it energetically favorable.

Question 4

Given the equation for free energy change $\Delta G = \Delta H - T \Delta S$, which scenario will most likely result in a spontaneous reaction?

Accepted Answer

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

Question 5

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

Accepted Answer

Synthesis of proteins from amino acids.

Question 6

A metabolic pathway is regulated by feedback inhibition. Which statement best describes this process?

Accepted Answer

The end product of the pathway inhibits an enzyme involved early in the pathway.

Question 7

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

Accepted Answer

Enzymes lower the activation energy barrier, increasing the rate of reaction.

Question 8

Which process in the cell is an example of energy coupling using ATP?

Accepted Answer

Active transport of ions across a membrane.

Question 9

A reaction has $\Delta H = -20$ kJ/mol and $\Delta S = 0.05$ kJ/(mol\cdot K). At $T = 300$ K, what is $\Delta G$ for the reaction?

Accepted Answer

$\Delta G = -20 - (300 	imes 0.05) = -35$ kJ/mol

Question 10

Which of the following statements about ATP is correct?

Accepted Answer

ATP is a universal energy carrier that provides energy for cellular work by hydrolysis to ADP and phosphate.

Question 11

Which of the following would increase the rate of an enzyme-catalyzed reaction?

Accepted Answer

Increasing substrate concentration up to the point of enzyme saturation.

Question 12

Which of the following is true regarding the Second Law of Thermodynamics in biological systems?

Accepted Answer

Every energy transformation increases the entropy of the universe.

Question 13

Which of the following reactions is most likely to be spontaneous at room temperature?

Accepted Answer

$\Delta H = -10$ kJ/mol, $\Delta S = +0.1$ kJ/(mol\cdot K)

Question 14

During glycolysis, glucose is broken down into pyruvate. This process is best described as:

Accepted Answer

A catabolic pathway that releases energy.

Question 15

Which of the following best explains why enzymes do not alter the $\Delta G$ of a reaction?

Accepted Answer

Enzymes only lower the activation energy, not the overall energy change.

Question 16

A cell needs to synthesize a large molecule from smaller precursors. Which process is most likely involved?

Accepted Answer

Anabolic pathway requiring energy input.

Question 17

Which of the following is a correct statement about metabolic equilibrium?

Accepted Answer

A cell at metabolic equilibrium is dead because no work can be performed.

Question 18

Which of the following is NOT a way that cells use ATP?

Accepted Answer

As a direct source of genetic information.

Question 19

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

Accepted Answer

It binds to a site other than the active site, reducing the maximum reaction rate.

Metabolism, Thermodynamics, and Enzyme Function in General Biology

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