Question 1

Which of the following best describes the second law of thermodynamics as it applies to biological systems?

Accepted Answer

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

Question 2

A scientist measures the change in free energy ($$\Delta G) $$for a chemical reaction in a cell and finds $$\Delta G = -12$$ kcal/mol. What does this indicate about the reaction?

Accepted Answer

The reaction is exergonic and can occur spontaneously.

Question 3

Which of the following is an example of a catabolic pathway?

Accepted Answer

Breakdown of glucose during cellular respiration.

Question 4

A metabolic pathway in a cell involves several steps, each catalyzed by a different enzyme. What is the main advantage of this organization?

Accepted Answer

It enables precise regulation and control of the pathway.

Question 5

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

Accepted Answer

ATP couples exergonic and endergonic reactions by providing energy through hydrolysis.

Question 6

A reaction has $$\Delta H = -20 kJ/$$mol, $$\Delta S = +0.05 kJ/($$mol\cdot K), and occurs at $$T = 300 K. $$Calculate $$\Delta G$$ and determine if the reaction is spontaneous.

Accepted Answer

$$\Delta G = -5 kJ/$$mol; the reaction is spontaneous.

Question 7

Which of the following statements about energy in biological systems is correct?

Accepted Answer

Chemical energy is a form of potential energy stored in molecular bonds.

Question 8

During cellular respiration, glucose is broken down and energy is released. Which law of thermodynamics does this process illustrate, and why?

Accepted Answer

Second law, because the process increases the entropy of the universe.

Question 9

Which of the following best explains why living organisms are considered open systems?

Accepted Answer

They absorb energy and matter from their surroundings and release waste products.

Question 10

A cell needs to drive an endergonic reaction with $$\Delta G = +8$$ kcal/mol. Which of the following strategies would allow the cell to accomplish this?

Accepted Answer

Couple the reaction to two ATP hydrolysis events, providing a total $$\Delta G = -14.6$$ kcal/mol.

Question 11

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

Accepted Answer

Exergonic reactions have a negative $$\Delta G$$ and can occur spontaneously.

Question 12

Which of the following real-life scenarios best illustrates the first law of thermodynamics?

Accepted Answer

A plant converting sunlight into chemical energy during photosynthesis.

Question 13

If a reaction in a cell has $$\Delta G = 0$$, what does this imply about the reaction?

Accepted Answer

The reaction is at equilibrium and no net work can be done.

Question 14

Which of the following is NOT a function of ATP in the cell?

Accepted Answer

Acting as a long-term energy storage molecule.

Question 15

A researcher adds an enzyme to a reaction and observes that the reaction rate increases. What is the most likely explanation for this observation?

Accepted Answer

The enzyme lowers the activation energy required for the reaction.

Question 16

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

Accepted Answer

Catabolic pathways release energy, which can be used to drive anabolic pathways.

Question 17

A cell is performing active transport to move ions against their concentration gradient. Which type of work is this, and what molecule typically provides the energy?

Accepted Answer

Transport work; ATP

Question 18

Which of the following statements about entropy is correct?

Accepted Answer

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

Question 19

In the ATP cycle, which process is responsible for regenerating ATP from ADP and inorganic phosphate ($$P_i$$)?

Accepted Answer

An exergonic reaction such as cellular respiration.

Question 20

A patient is diagnosed with a metabolic disorder that prevents the breakdown of glucose. Which type of metabolic pathway is most directly affected?

Accepted Answer

Catabolic pathway

Chapter 8: An Introduction to Metabolism – Study Notes

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