Q: In a red blood cell, the actual concentrations of glucose-6-phosphate and fructose-6-phosphate are 83 µM and 14 µM, respectively. If the standard free energy change ($$\Delta G^\circ) $$for the reaction is $$+410$$ cal/mol, which equation would you use to calculate the actual free energy change ($$\Delta G) $$under these conditions?

$$\Delta G = \Delta G^\circ + RT \ln \frac{[\text{fructose-6-phosphate}]}{[\text{glucose-6-phosphate}]}$$

Question 1

Which of the following best describes the role of free energy change ($$\Delta G) in $$determining whether a cellular reaction will occur spontaneously?

Accepted Answer

$$\Delta G$$ must be negative for a reaction to be spontaneous.

Question 2

A cell is actively importing glucose against its concentration gradient. Which category of cellular work does this process exemplify?

Accepted Answer

Concentration work

Question 3

Which equation correctly relates 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 4

During photosynthesis, plants convert carbon dioxide and water into glucose and oxygen using sunlight. This process is an example of:

Accepted Answer

Synthetic work

Question 5

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

Accepted Answer

The total amount of energy in the universe remains constant.

Question 6

A nerve cell maintains a membrane potential by pumping Na$$^+$$ ions out and K$$^+$$ ions in. What type of cellular work is this?

Accepted Answer

Electrical work

Question 7

Which of the following is true regarding entropy ($$\Delta S) in $$biological systems?

Accepted Answer

Entropy may increase, decrease, or remain the same in biological systems.

Question 8

If a reaction in a cell has $$\Delta H \u003e 0$$ and $$\Delta S \u003e 0$$, under what condition will it be spontaneous?

Accepted Answer

At high temperatures

Question 9

Which formula allows you to calculate the equilibrium constant ($$K_{eq}) $$from the standard free energy change ($$\Delta G^\circ$$)?

Accepted Answer

$$\Delta G^\circ = -RT \ln K_{eq}$$

Question 10

A cell maintains a steady state far from equilibrium. What does this imply about the cell’s metabolic reactions?

Accepted Answer

Reactions are continuously driven and net work is performed.

Question 11

Which of the following is NOT one of the six categories of cellular events that require energy?

Accepted Answer

Transport of genetic information

Question 12

In a red blood cell, the actual concentrations of glucose-6-phosphate and fructose-6-phosphate are 83 µM and 14 µM, respectively. If the standard free energy change ($$\Delta G^\circ) $$for the reaction is $$+410$$ cal/mol, which equation would you use to calculate the actual free energy change ($$\Delta G) $$under these conditions?

Accepted Answer

$$\Delta G = \Delta G^\circ + RT \ln \frac{[	ext{fructose-6-phosphate}]}{[	ext{glucose-6-phosphate}]}$$

Question 13

Which statement best explains why no biological process is 100% efficient?

Accepted Answer

Some energy is always lost as heat to the environment.

Question 14

Which of the following is an example of an exergonic reaction in cells?

Accepted Answer

Oxidation of glucose to carbon dioxide and water

Question 15

What is the significance of the equilibrium constant ($$K_{eq}) in $$cellular reactions?

Accepted Answer

It indicates the ratio of product to reactant concentrations at equilibrium.

Question 16

Which of the following best describes the difference between endothermic and endergonic reactions?

Accepted Answer

Endothermic reactions absorb heat; endergonic reactions absorb free energy.

Question 17

Which of the following is a real-life example of bioluminescence in cell biology research?

Accepted Answer

Use of green fluorescent protein (GFP) to visualize cellular processes

Question 18

If a reaction has $$\Delta G^\circ = 0$$, what does this indicate about the reaction under standard conditions?

Accepted Answer

The reaction is at equilibrium.

Question 19

Why is it important for cells to remain in a steady state rather than reach equilibrium?

Accepted Answer

At equilibrium, there is no net flow of matter and the cell would be dead.

Question 20

Which of the following best describes the relationship between $$\Delta G^\circ$$ and $$K_{eq}$$?

Accepted Answer

$$\Delta G^\circ is $$negative when $$K_{eq} \u003e 1$$

Bioenergetics: The Flow of Energy in the Cell – Study Notes

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