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 $$\Delta G of$$ $$-20 kJ/$$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 hydrolysis of ATP is often coupled to endergonic reactions in cells?

Accepted Answer

ATP hydrolysis releases free energy that can drive non-spontaneous reactions.

Question 4

According to the Second Law of Thermodynamics, what happens to the entropy of a closed system over time?

Accepted Answer

Entropy increases as the system becomes more disordered.

Question 5

Which of the following reactions is most likely to be exergonic?

Accepted Answer

The hydrolysis of sucrose into glucose and fructose.

Question 6

Enzymes speed up chemical reactions by:

Accepted Answer

Lowering the activation energy ($$E_A) $$required for the reaction.

Question 7

Which of the following best describes the relationship between exergonic and endergonic reactions in metabolism?

Accepted Answer

Endergonic reactions are driven by the energy released from exergonic reactions.

Question 8

A reaction has a positive $$\Delta G. $$Which of the following statements is true?

Accepted Answer

The reaction is non-spontaneous and requires energy input.

Question 9

Which of the following is an example of an oxidation reaction?

Accepted Answer

A molecule loses electrons during a redox reaction.

Question 10

In a biological system, what is the main consequence of energy being converted to heat during metabolic reactions?

Accepted Answer

The heat increases the entropy of the system and is considered lost energy.

Question 11

Which of the following best describes the role of high-energy electrons in cellular metabolism?

Accepted Answer

They are a way of transferring energy from one molecule to another.

Question 12

If a reaction has a high activation energy ($$E_A$$), what is the most likely effect on the rate of the reaction at room temperature?

Accepted Answer

The reaction will proceed slowly or not at all.

Question 13

Which of the following is true about enzymes and the thermodynamics of a reaction?

Accepted Answer

Enzymes lower the activation energy but do not affect $$\Delta G.$$

Question 14

A cell needs to synthesize a complex molecule from simpler precursors. Which of the following statements is most accurate?

Accepted Answer

This process is likely endergonic and requires energy input.

Question 15

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

Accepted Answer

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

Question 16

Which of the following best describes the fate of energy that is 'lost' as heat during metabolic reactions?

Accepted Answer

It increases the entropy of the surroundings and cannot be used to do work.

Question 17

In the context of redox reactions, which statement is correct?

Accepted Answer

The oxidizing agent gains electrons and is reduced.

Question 18

Which of the following scenarios best illustrates the Second Law of Thermodynamics in a biological context?

Accepted Answer

A cell uses energy from ATP hydrolysis to decrease its internal entropy while increasing the entropy of its surroundings.

Question 19

Which of the following is a correct statement about the coupling of exergonic and endergonic reactions in metabolism?

Accepted Answer

Endergonic reactions are powered by the energy released from exergonic reactions.

Question 20

Which of the following best explains why enzymes are essential for life?

Accepted Answer

They lower the activation energy, allowing reactions to occur at biological temperatures.

Energy, Thermodynamics, and Chemical Reactions in Biology

Study Guide - Practice Questions