Question 1

Which of the following best describes the difference between an open system and a closed system in biological contexts?

Accepted Answer

An open system exchanges both energy and matter with its surroundings, while a closed system exchanges neither.

Question 2

Which of the following reactions is most oxidized, based on the progression from methane to carbon dioxide?

Accepted Answer

Carbon dioxide $$\left( \mathrm{CO_2$} \right)$$

Question 3

In the context of cellular energy, why do cells maintain a high ATP/ADP ratio rather than allowing the reaction $$\mathrm{ATP} \rightleftharpoons \mathrm{ADP} + \mathrm{H_2O} to $$reach equilibrium?

Accepted Answer

Because a high ATP/ADP ratio ensures a steady supply of free energy for endergonic reactions.

Question 4

Which of the following best explains why fatty acids are considered a dense form of energy storage?

Accepted Answer

Fatty acids contain a high proportion of reduced carbon atoms, which release more energy upon oxidation.

Question 5

A reaction has $$\Delta G^\circ' \u003c 0. $$Which of the following statements is true under standard conditions?

Accepted Answer

The reaction will proceed spontaneously to the right.

Question 6

Which of the following is an example of mechanical work in cells?

Accepted Answer

Muscle contraction during exercise

Question 7

Which of the following best describes the relationship between free energy change ($$\Delta G$$), enthalpy change ($$\Delta H$$), and entropy change ($$\Delta S) at $$constant temperature?

Accepted Answer

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

Question 8

Which of the following statements about the oxidation state of carbon is correct?

Accepted Answer

As carbon is oxidized, it loses electrons and releases energy.

Question 9

In the context of the energy cycle between phototrophs and chemotrophs, which of the following is true?

Accepted Answer

Chemotrophs use organic compounds produced by phototrophs for energy.

Question 10

A cell is placed in a situation where the ATP/ADP ratio drops to 1:1. What is the most likely consequence?

Accepted Answer

The cell will be unable to drive endergonic reactions efficiently.

Question 11

Which of the following best describes the steady state of ATP and ADP in a living cell?

Accepted Answer

ATP is maintained at a much higher concentration than ADP at steady state.

Question 12

Which of the following is an example of concentration work in cells?

Accepted Answer

Active transport of ions against a gradient

Question 13

If a reaction has $$K_{eq} = 1$$, what can be said about $$\Delta G^\circ'$$?

Accepted Answer

$$\Delta G^\circ' is $$zero

Question 14

Which of the following best explains why the oxidation of glucose releases energy?

Accepted Answer

Glucose contains more reduced carbon atoms, which release energy when oxidized to carbon dioxide.

Question 15

Which of the following is true about the equilibrium constant ($$K_{eq}) $$and the direction of a chemical reaction?

Accepted Answer

If $$K_{eq} \u003e 1$$, products predominate at equilibrium.

Question 16

Which of the following best describes the role of entropy ($$\Delta S) in $$determining the spontaneity of a reaction?

Accepted Answer

A positive $$\Delta S$$ can contribute to a negative $$\Delta G$$, making a reaction spontaneous.

Question 17

Which of the following is an example of electrical work in cells?

Accepted Answer

Generation of a membrane potential in mitochondria

Question 18

Which of the following statements about the conversion of glucose-6-phosphate to fructose-6-phosphate is correct?

Accepted Answer

It is an isomerization reaction involving the rearrangement of a carbonyl group.

Question 19

Which of the following best explains why cells do not allow ATP hydrolysis to reach equilibrium?

Accepted Answer

Equilibrium would deplete ATP, preventing the cell from performing necessary work.

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

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