Question 1

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

Accepted Answer

Kinetic energy is the energy of motion, such as ions moving across a membrane, while potential energy is stored due to position or structure, such as a concentration gradient.

Question 2

A cell maintains a high concentration of potassium ions ($$K^+) $$inside and a low concentration outside. What type of energy does this concentration gradient represent?

Accepted Answer

Potential energy, because the gradient can be used to do work.

Question 3

Which statement best summarizes the First Law of Thermodynamics as it applies to living cells?

Accepted Answer

Energy can be transformed from one form to another, but the total amount of energy remains constant.

Question 4

According to the Second Law of Thermodynamics, what happens to the entropy of a system during energy transformations?

Accepted Answer

Entropy increases, making the system more disordered.

Question 5

Which of the following equations correctly represents Gibbs Free Energy?

Accepted Answer

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

Question 6

A reaction has $$\Delta H = -10$$ kcal/mol and $$\Delta S = +0.02$$ kcal/(mol·K)$$. At T = 300$ K, what is $$\Delta G$ for the reaction?

Accepted Answer

$$\Delta G = -10.6$$ kcal/mol

Question 7

Which of the following best explains why bonds with longer bond lengths have greater potential (chemical) energy?

Accepted Answer

Longer bonds are weaker and less stable, so they store more potential energy.

Question 8

Which of the following changes would increase the potential chemical energy of a molecule?

Accepted Answer

Increasing the number of bonds in the molecule.

Question 9

Which of the following statements about exergonic reactions is FALSE?

Accepted Answer

The products have higher enthalpy than the reactants.

Question 10

A protein is broken down into amino acids in a cell. Which of the following best describes this process?

Accepted Answer

It is an exergonic reaction because it increases entropy and releases energy.

Question 11

Which of the following scenarios represents an endergonic reaction?

Accepted Answer

Synthesis of glucose-6-phosphate from glucose and $$P_i$$ ($$\Delta G = +3.3$$ kcal/mol)

Question 12

Which of the following factors does NOT increase the potential chemical energy of a molecule?

Accepted Answer

Increasing the difference in electronegativity between bonded atoms.

Question 13

Which of the following best describes the relationship between bond length and electronegativity difference?

Accepted Answer

Bond length decreases as electronegativity difference increases.

Question 14

Which of the following molecules would have the highest potential chemical energy in its bonds?

Accepted Answer

A molecule with many single bonds and a long, unbranched carbon chain.

Question 15

Which of the following is TRUE about the energy changes in an endergonic reaction?

Accepted Answer

The products have higher enthalpy and lower entropy than the reactants.

Question 16

Which of the following best explains why energy is released when bonds break during a chemical reaction?

Accepted Answer

The formation of new, more stable bonds releases more energy than is required to break the original bonds.

Question 17

A reaction has $$\Delta H = +5$$ kcal/mol and $$\Delta S = +0.03$$ kcal/(mol·K). At $$T = 300 K$$, is this reaction exergonic or endergonic?

Accepted Answer

Endergonic, because $$\Delta G is $$positive.

Question 18

Which of the following statements about entropy is correct?

Accepted Answer

Entropy is a measure of the number of possible states a system can take on.

Question 19

Which of the following best describes the effect of temperature on Gibbs free energy?

Accepted Answer

Increasing temperature increases the impact of entropy ($$\Delta S) on$$ $$\Delta G.$$

Question 20

Which of the following is a real-life example of the Second Law of Thermodynamics?

Accepted Answer

A living cell converting glucose to ATP, with some energy lost as heat.

Energy and Metabolism: Foundations of Biological Thermodynamics

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