Q: Cellular respiration has the following standard values: $$\Delta H = -686$$ kcal/mol, $$\Delta S = +0.18$$ kcal/mol·K, $$T = 298 K. $$What is the value of $$\Delta G$$ for this reaction?

$$ \Delta G = -686 - (298 \times 0.18) = -739.64 \text{ kcal/mol} $$

Question 1

Which of the following best describes a catabolic pathway in cellular metabolism?

Accepted Answer

A pathway that releases energy by breaking down complex molecules into simpler compounds, such as cellular respiration.

Question 2

Which of the following statements about the first law of thermodynamics is correct?

Accepted Answer

Energy can be transferred and transformed, but it cannot be created or destroyed.

Question 3

A student places a ball on a high shelf. Which type of energy transformation is primarily involved in this scenario?

Accepted Answer

Conversion of chemical energy to potential energy.

Question 4

Which equation correctly represents the Gibbs free energy change for a reaction?

Accepted Answer

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

Question 5

Cellular respiration has the following standard values: $$\Delta H = -686$$ kcal/mol, $$\Delta S = +0.18$$ kcal/mol·K, $$T = 298 K. $$What is the value of $$\Delta G$$ for this reaction?

Accepted Answer

$$ \Delta G = -686 - (298 	imes 0.18) = -739.64 	ext{ kcal/mol} $$

Question 6

Which of the following is true about exergonic and endergonic reactions?

Accepted Answer

Exergonic reactions have a negative $$\Delta G$$ and are spontaneous.

Question 7

Which of the following best explains why ATP hydrolysis releases energy?

Accepted Answer

The energy is released due to the chemical change to a state of lower free energy, not from the phosphate bonds themselves.

Question 8

A cell uses the sodium-potassium pump to move sodium ions out and potassium ions in, both against their concentration gradients. Which statement best describes the energetics of this process?

Accepted Answer

It is an endergonic process coupled to the exergonic hydrolysis of ATP.

Question 9

Which of the following is an example of energy coupling in cells?

Accepted Answer

The use of ATP hydrolysis to drive the synthesis of glutamine from glutamic acid and ammonia.

Question 10

Which of the following statements about the second law of thermodynamics is correct?

Accepted Answer

Every energy transfer or transformation increases the entropy of the universe.

Question 11

Why does the evolution of complex organisms not violate the second law of thermodynamics?

Accepted Answer

Because entropy may decrease in a system, but the total entropy of the universe increases.

Question 12

Which of the following is NOT a form of kinetic energy?

Accepted Answer

Chemical energy

Question 13

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

Accepted Answer

Each step in a metabolic pathway is catalyzed by a specific enzyme, lowering the activation energy.

Question 14

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

Accepted Answer

The synthesis of proteins from amino acids.

Question 15

Which of the following statements about free energy and stability is correct?

Accepted Answer

A spontaneous change decreases the free energy of the system, making it more stable.

Question 16

Which of the following is true regarding the relationship between entropy and biological order?

Accepted Answer

Cells create order locally, but overall increase the entropy of the universe.

Question 17

Which of the following is a correct interpretation of a positive $$\Delta G$$ for a chemical reaction?

Accepted Answer

The reaction is endergonic and requires energy input.

Question 18

Which of the following is an example of chemical work powered by ATP in cells?

Accepted Answer

The synthesis of glutamine from glutamic acid and ammonia.

Question 19

Which of the following best describes the difference between open and isolated systems in thermodynamics?

Accepted Answer

Open systems can exchange both energy and matter with their surroundings, while isolated systems cannot exchange either.

Energy, Metabolism, and Thermodynamics in Biological Systems

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