Question 1

Which of the following best describes the relationship between the equilibrium constant ($$K_{eq}) $$and the direction of a chemical reaction?

Accepted Answer

A reaction with $$K_{eq} = 1$$ has equal concentrations of products and reactants at equilibrium.

Question 2

Given the reaction $$G6P \rightleftharpoons F6P$$ with $$K_{eq} = 0.5$$, and cellular concentrations $$[G6P] = 10\ \mu M$$ and $$[F6P] = 1\ \mu M$$, what is the direction of the reaction and why?

Accepted Answer

The reaction proceeds toward F6P because the product/reactant ratio is less than $$K_{eq}.$$

Question 3

Which equation correctly relates the standard free energy change ($$\Delta G^\circ') to $$the equilibrium constant ($$K'_{eq}$$)?

Accepted Answer

$$\Delta G^\circ' = -RT \ln K'_{eq}$$

Question 4

If $$\Delta G'$$ for a reaction is negative under cellular conditions, what does this indicate about the reaction?

Accepted Answer

The reaction is thermodynamically favorable and will proceed spontaneously as written.

Question 5

For the reaction $$aA + bB \rightarrow cC + dD$$, which formula gives the actual free energy change ($$\Delta G) $$under non-standard conditions?

Accepted Answer

$$\Delta G = -RT \ln K_{eq} + RT \ln \frac{[C]^c_{pr}[D]^d_{pr}}{[A]^a_{pr}[B]^b_{pr}}$$

Question 6

A red blood cell has $$[G6P] = 83\ \mu M$$ and $$[F6P] = 14\ \mu M. $$Given $$K_{eq} = 0.5$$ and $$\Delta G^\circ' = +410$$ cal/mol, what is $$\Delta G'$$ for the reaction $$G6P \rightarrow F6P$$? Use $$RT = 592$$ cal/mol.

Accepted Answer

$$\Delta G' = +410 + 592 \ln(0.169) = -644$$ cal/mol

Question 7

Which statement best explains why $$\Delta G^\circ' is $$not always a valid measure of reaction spontaneity in cells?

Accepted Answer

$$\Delta G^\circ'$$ does not account for actual cellular concentrations of reactants and products.

Question 8

In the jumping bean analogy for bioenergetics, what does the movement of beans from compartment 1 to compartment 2 represent?

Accepted Answer

The tendency of a system to move toward equilibrium, increasing entropy.

Question 9

Which of the following is true about a reaction with $$\Delta G = 0$$?

Accepted Answer

The reaction is at equilibrium under the conditions for which $$\Delta G$$ was calculated.

Question 10

A reaction has $$\Delta G^\circ' = -1000$$ cal/mol. What can you conclude about $$K'_{eq}$$?

Accepted Answer

$$K'_{eq} \u003e 1$$

Question 11

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

Accepted Answer

An increase in entropy contributes to a negative $$\Delta G$$, favoring spontaneity.

Question 12

Which of the following scenarios would result in a positive $$\Delta G$$ for a reaction?

Accepted Answer

The product/reactant ratio is much greater than $$K_{eq}.$$

Question 13

Which of the following is the correct interpretation of $$\Delta G^\circ' \u003c 0$$ for a reaction?

Accepted Answer

The reaction will proceed spontaneously to the right under standard conditions.

Question 14

If a reaction in a cell has $$\Delta G' \u003e 0$$, what must be true for the reaction to proceed?

Accepted Answer

Energy must be supplied to drive the reaction.

Question 15

Which of the following best explains why cells maintain concentrations of reactants and products far from equilibrium?

Accepted Answer

To maximize the amount of work that can be done by metabolic reactions.

Question 16

In the context of bioenergetics, what does the ability to do work depend on?

Accepted Answer

The difference in free energy ($$\Delta G) $$between reactants and products.

Bioenergetics: The Flow of Energy in the Cell

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