Q: Which of the following equations correctly represents the change in free energy for a chemical reaction?

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

Question 1

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

Accepted Answer

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

Question 2

A chemical reaction has a $$\Delta G of$$ $$-30 kJ/$$mol. Which of the following is true about this reaction?

Accepted Answer

The reaction is exergonic and will occur spontaneously.

Question 3

Which of the following best explains why the conversion of glucose to carbon dioxide and water in cellular respiration increases entropy?

Accepted Answer

The process releases energy and increases the randomness of the system.

Question 4

According to the Second Law of Thermodynamics, what happens to the energy that is 'lost' during a chemical reaction in a cell?

Accepted Answer

It is released as heat, increasing the entropy of the surroundings.

Question 5

Which of the following equations correctly represents the change in free energy for a chemical reaction?

Accepted Answer

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

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 scientist mixes two reactants in a test tube and observes that the temperature increases and the products have less free energy than the reactants. Which type of reaction has occurred?

Accepted Answer

Exergonic reaction

Question 8

Which of the following is an example of an endergonic reaction in living cells?

Accepted Answer

Formation of peptide bonds during protein synthesis

Question 9

If a reaction has a high activation energy ($$E_A$$), what is the most likely effect of adding an enzyme specific to that reaction?

Accepted Answer

The reaction will proceed faster because the activation energy is lowered.

Question 10

Which of the following statements about ATP is correct?

Accepted Answer

ATP contains high-energy covalent bonds between its phosphate groups.

Question 11

During a coupled reaction, the hydrolysis of ATP ($$\Delta G = -30.5 kJ/$$mol) is used to drive an endergonic reaction with $$\Delta G = +20 kJ/$$mol. What is the net $$\Delta G$$ for the coupled process?

Accepted Answer

$$\Delta G = -10.5 kJ/$$mol

Question 12

Which of the following best describes an oxidation-reduction (redox) reaction?

Accepted Answer

A reaction in which one molecule loses electrons and another gains electrons.

Question 13

In a redox reaction, which molecule acts as the oxidizing agent?

Accepted Answer

The molecule that gains electrons.

Question 14

Which of the following scenarios best illustrates the concept of entropy as described by the Second Law of Thermodynamics?

Accepted Answer

A crystal of salt dissolving in water, increasing the randomness of the ions.

Question 15

Which of the following statements about exergonic and endergonic reactions is correct?

Accepted Answer

Exergonic reactions are spontaneous, while endergonic reactions are not.

Question 16

A reaction in a cell has a positive $$\Delta G. $$Which of the following is most likely to occur?

Accepted Answer

The reaction will require an input of energy to proceed.

Question 17

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

Accepted Answer

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

Question 18

Which of the following is a real-life example of energy coupling in cells?

Accepted Answer

The use of ATP hydrolysis to drive the active transport of ions across a membrane.

Question 19

If a reaction has a $$\Delta G of$$ $$+8.1 kJ/$$mol, which of the following statements is true?

Accepted Answer

The reaction is endergonic and requires energy input.

Question 20

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

Accepted Answer

Catabolic pathways release energy that can be used to drive anabolic pathways.

Energy, Thermodynamics, and Chemical Reactions in Biology

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