Question 1

Which of the following best describes a chemoheterotroph, according to the classification flowchart for energy and carbon acquisition?

Accepted Answer

An organism that obtains both energy and carbon from organic compounds.

Question 2

Which metabolic pathway is characterized by the assembly of small molecules into larger ones, and what is the energy implication of this process?

Accepted Answer

Anabolic pathway; energy is required.

Question 3

In the context of cellular energy, which of the following is an example of potential energy?

Accepted Answer

A ball at the top of a ramp before it rolls down.

Question 4

Which of the following equations correctly relates Gibbs free energy change ($$\Delta G$$), enthalpy change ($$\Delta H$$), and entropy change ($$\Delta S) at $$temperature $$T$$?

Accepted Answer

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

Question 5

A reaction has $$\Delta H = -100 kJ/$$mol and $$\Delta S = -0.2 kJ/($$mol·K). At $$T = 300 K$$, what is $$\Delta G$$ and is the reaction spontaneous?

Accepted Answer

$$\Delta G = -40 kJ/$$mol; spontaneous

Question 6

Which of the following statements about the first law of thermodynamics is correct in the context of cellular metabolism?

Accepted Answer

Energy is transformed from one form to another, but the total energy remains constant.

Question 7

Which process is an example of an exergonic reaction in biological systems?

Accepted Answer

ATP hydrolysis to ADP and inorganic phosphate

Question 8

Why do cells require enzymes for many exergonic reactions?

Accepted Answer

Because enzymes lower the activation energy ($$E_a$$), allowing reactions to proceed at physiologically relevant rates.

Question 9

Which of the following best explains why living organisms do not violate the second law of thermodynamics?

Accepted Answer

They maintain internal order by increasing the entropy of their surroundings.

Question 10

During the oxidation of glucose in cellular respiration, which of the following statements is true?

Accepted Answer

The process is exergonic and releases energy that can be captured as ATP.

Question 11

Which of the following is a real-life example of coupling an endergonic reaction to an exergonic one in cells?

Accepted Answer

ATP hydrolysis powering the active transport of Na$$^+$$ and K$$^+$$ ions across the plasma membrane

Question 12

Which of the following best describes the difference between exergonic and exothermic reactions?

Accepted Answer

Exergonic reactions have $$\Delta G \u003c 0$$, while exothermic reactions have $$\Delta H \u003c 0.$$

Question 13

A cell maintains a high concentration of K$$^+$$ ions inside and Na$$^+$$ ions outside. What type of work is this an example of?

Accepted Answer

Concentration work

Question 14

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

Accepted Answer

Synthesis of macromolecules

Question 15

Which of the following best describes the role of entropy ($$\Delta S) in $$protein folding?

Accepted Answer

Protein folding decreases the entropy of the protein but increases the entropy of the surrounding water.

Question 16

Which of the following is a correct statement about the flow of energy and matter in the biosphere?

Accepted Answer

Energy flows unidirectionally, while matter cycles between phototrophs and chemotrophs.

Question 17

Which of the following best explains why equilibrium is not desirable for living cells?

Accepted Answer

Equilibrium means no net energy or matter flow, which is incompatible with life.

Question 18

Which of the following is true about the efficiency of biological energy conversion, such as glucose metabolism?

Accepted Answer

It is approximately 38% efficient, with the rest lost as heat.

Question 19

Which of the following is a correct interpretation of the melting of an ice cube at room temperature in terms of $$\Delta H$$, $$\Delta S$$, and $$\Delta G$$?

Accepted Answer

$$\Delta H is $$positive, $$\Delta S is $$positive, $$\Delta G is $$negative

Question 20

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

Accepted Answer

ATP is used to couple exergonic and endergonic reactions, providing energy for cellular work.

Bioenergetics: The Flow of Energy in the Cell (Sections 5.1 & 5.2) – Study Notes

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