Question 1

Which of the following 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 reaction has $$\Delta H = -50 kJ/$$mol and $$\Delta S = +0.1 kJ/($$mol\cdot K)$$. At T = 298$ K, what is the value of $$\Delta G$ and is the reaction spontaneous?

Accepted Answer

$$\Delta G = -20.2 kJ/$$mol; the reaction is spontaneous

Question 3

Which type of biological work is illustrated by the active transport of ions across a membrane to create a charge gradient?

Accepted Answer

Electrical work

Question 4

If a chemical reaction in a cell has $$\Delta G' = +5 kJ/$$mol, what does this indicate about the reaction under cellular conditions?

Accepted Answer

The reaction is nonspontaneous and requires energy input.

Question 5

Which equation correctly relates free energy change to enthalpy and entropy?

Accepted Answer

$$\Delta G = \Delta H - T\Delta S$$

Question 6

A cell maintains a high concentration of glucose inside compared to outside. What type of work is this an example of?

Accepted Answer

Concentration work

Question 7

Given the reaction $$A \rightleftharpoons B$$, if $$[A] = 16.4$$ mmol and $$[B] = 67.8$$ mmol at equilibrium, what is the equilibrium constant $$K_{eq}$$?

Accepted Answer

$$K_{eq} = 4.13$$

Question 8

Which of the following statements about entropy ($$S) is $$correct?

Accepted Answer

Entropy is a measure of disorder or randomness in a system.

Question 9

The oxidation of glucose is an example of which type of reaction?

Accepted Answer

Exergonic and exothermic

Question 10

Which formula allows you to calculate the standard free energy change ($$\Delta G^\circ') $$for a reaction?

Accepted Answer

$$\Delta G^\circ' = -RT \ln K_{eq}$$

Question 11

If a reaction has $$\Delta H \u003e 0$$ and $$\Delta S \u003c 0$$, what can you conclude about $$\Delta G$$ and the spontaneity of the reaction at all temperatures?

Accepted Answer

$$\Delta G$$ will always be positive; the reaction is never spontaneous.

Question 12

Why do cells couple exergonic and endergonic reactions?

Accepted Answer

To use the energy released from exergonic reactions to drive endergonic reactions.

Question 13

Which of the following best explains why cells maintain a steady state rather than equilibrium?

Accepted Answer

A steady state allows cells to continuously perform work and sustain life.

Question 14

A reaction has $$\Delta G^\circ' = -10 kJ/$$mol. What does this indicate about the reaction under standard conditions?

Accepted Answer

The reaction is spontaneous under standard conditions.

Question 15

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

Accepted Answer

Thermodynamic work

Question 16

If $$\Delta G = 0$$ for a reaction, what does this mean about the reaction?

Accepted Answer

The reaction is at equilibrium.

Question 17

Which of the following best describes the role of ATP in cellular metabolism?

Accepted Answer

ATP couples exergonic and endergonic reactions by providing free energy.

Question 18

A reaction in a cell has $$[reactant] = 150$$ mmol and $$[product] = 10$$ mmol. If $$K_{eq} = 4.13$$, what can you say about the direction of the reaction?

Accepted Answer

The reaction will proceed in the reverse direction to reach equilibrium.

Question 19

Which of the following is true about oxidation-reduction (redox) reactions in biological systems?

Accepted Answer

Oxidation involves the loss of electrons, and reduction involves the gain of electrons.

Bioenergetics and Thermodynamics in Cell Biology

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