Question 1

Living things are _____

Accepted Answer

Living things are considered an open system because they exchange energy and matter with their environment.

Question 2

I am performing a reaction, A → B, with Δ G ° ' = − 5000 kJ\mol. I start the reaction with 10 mM A and no B. After allowing the reaction to proceed for 24 hrs at room temperature and atmospheric pressure, I analyze a sample of the reaction mix to find I now have 8 mM A and 2 mM B. Which of the following conclusions should I make?

Accepted Answer

The negative ΔG°' indicates that the reaction is thermodynamically favorable, meaning it should proceed towards the formation of B. However, since there is still a significant amount of A left and only a small amount of B has formed, the reaction has not yet reached equilibrium. This suggests that given more time, more A could potentially convert to B until equilibrium is reached.

Question 3

By definition, a spontaneous reaction is one in which

Accepted Answer

A spontaneous reaction is one in which energy is released. This release of energy (often in the form of heat) drives the reaction forward without the need for continuous external energy input.

Question 4

A biological reaction with a significantly postive Δ G under cellular conditions may proceed in the forward direction because

Accepted Answer

Reactions with a positive ΔG (Gibbs free energy change) indicate that they are not spontaneous under standard conditions. However, cells can drive such reactions forward by coupling them to other reactions that release a larger amount of energy (negative ΔG), making the overall process energetically favorable. This is a common strategy in metabolic pathways.

Question 5

In general, catabolism

Accepted Answer

Catabolism involves the breakdown of complex molecules into simpler ones, releasing energy in the process.

Question 6

The production of larger molecules from smaller ones is called

Accepted Answer

The production of larger molecules from smaller ones is called anabolism. It is a constructive process by which organisms synthesize complex molecules from simpler ones, typically requiring energy.

Question 7

The standard state of a solution is taken as

Accepted Answer

The standard state of a solution is taken as 1 molar concentration, which is a way to standardize conditions for comparing the properties of solutions.

Question 8

Which of the following statements concerning the free energy change ( Δ G) is false ?

Accepted Answer

The rate of a reaction is not determined by the free energy change (ΔG) but rather by the activation energy and the temperature, among other factors. ΔG indicates the spontaneity of a reaction, not its rate.

Question 9

"Metabolism" refers to

Accepted Answer

Metabolism encompasses both anabolic processes (the production of larger molecules from smaller ones) and catabolic processes (the breakdown of larger molecules into smaller ones).

Question 10

I am performing a reaction, A → B, with Δ G ° ' = − 0.3 kJ\mol. I start the reaction with 10 mM A and no B. After allowing the reaction to proceed for 24 hrs at room temperature and atmospheric pressure, I analyze a sample of the reaction mix to find I now have 1 mM A and 9 mM B. Which of the following conclusions should I make?

Accepted Answer

The answer of I am performing a reaction, A →...

Question 11

Biochemists use a modified value for standard Δ G values because

Accepted Answer

The answer of Biochemists use a modified value for standard...

Question 12

In general, catabolism

Accepted Answer

Catabolism is an oxidative process that releases energy by breaking down complex molecules into simpler ones.

Question 13

Which best describes the Δ G for hydrolysis of creatine phosphate under cellular conditions in which the concentration of creatine phosphate, creatine, and phosphate all equal 1 mM at 25 ° C. The Δ G ° for the hydrolysis of creatine phosphate at 25 ° C is − 43 kJ\mol.

Accepted Answer

Under standard conditions, where all reactants and products are at 1 M concentration, ΔG equals ΔG°. Since the concentrations given are 1 mM, which is not standard, but equal for reactants and products, ΔG will still be approximately equal to ΔG°.

Question 14

Consider this rxn which has a Δ G ° = +0.4 kJ\mol.
A + B ↔ C + D
1 M A, 1 M B, 0.1 M C and 0.1 M D are added to a container at room temperature. Which of the following statements is true?

Accepted Answer

The reaction quotient Q = [C][D]/[A][B] = (0.1)(0.1)/(1)(1) = 0.01. Since ΔG° = +0.4 kJ/mol, the reaction is not at equilibrium. ΔG = ΔG° + RTlnQ. Given Q < 1, lnQ < 0, making ΔG < ΔG°. Since ΔG° is positive, ΔG is still positive but less than ΔG°.

Question 15

Consider this rxn which has a Δ G ° = +0.4 kJ\mol.
A + B ↔ C + D
1 M A, 1 M B, 0.1 M C and 0.1 M D are added to a container at room temperature. Which of the following statements is true?

Accepted Answer

Given the positive ΔG° value, the reaction is not spontaneously favorable in the forward direction under standard conditions. However, the reaction quotient Q (which is [C][D]/[A][B] in this case) is lower than the equilibrium constant K (since ΔG° is positive, K < 1), indicating the reaction will proceed in the forward direction to reach equilibrium.

Question 16

Which of the following is not true concerning standard states?

Accepted Answer

The standard state for pure liquids is not 1M; it is the pure liquid under its own pressure (usually 1 atmosphere). For solutes in solution, the standard state is 1M, which is correctly stated in option D.

Question 17

An isolated system can exchange ______ with its surroundings

Accepted Answer

An isolated system cannot exchange either energy or matter with its surroundings, by definition.

Question 18

Which of the following statements apply to anabolism?

Accepted Answer

Anabolism is a constructive metabolic process where simpler substances are combined to form more complex molecules. It proceeds in stages, requires energy (usually in the form of ATP), and often involves reducing agents to add electrons, facilitating the synthesis of complex molecules.

Question 19

Consider this rxn which has a Δ G ° = +0.4 kJ\mol. Succinate + FAD ↔ fumarate + FADH₂ 1 mM of each compound are mixed & the reaction is allowed to come to equilibrium. Which statement is correct about the resulting concentration of FAD at equilibrium?

Accepted Answer

The positive ΔG° indicates that the reaction is not spontaneous in the forward direction under standard conditions, suggesting that at equilibrium, the concentration of reactants (including FAD) will be greater than the concentration of products (including FADH2).

Question 20

The standard state usually used in biochemistry ( Δ G ° ') includes

Accepted Answer

The answer of The standard state usually used in biochemistry...

Quiz 15: The Importance of Energy Changes and Electron Transfer in Metabolism

Living things are _____

By definition, a spontaneous reaction is one in which

A biological reaction with a significantly postive Δ G under cellular conditions may proceed in the forward direction because

In general, catabolism

The production of larger molecules from smaller ones is called

The standard state of a solution is taken as

Which of the following statements concerning the free energy change ( Δ G) is false ?

"Metabolism" refers to

Biochemists use a modified value for standard Δ G values because

In general, catabolism

Which best describes the Δ G for hydrolysis of creatine phosphate under cellular conditions in which the concentration of creatine phosphate, creatine, and phosphate all equal 1 mM at 25 ° C. The Δ G ° for the hydrolysis of creatine phosphate at 25 ° C is − 43 kJ\mol.

Consider this rxn which has a Δ G ° = +0.4 kJ\mol. A + B ↔ C + D 1 M A, 1 M B, 0.1 M C and 0.1 M D are added to a container at room temperature. Which of the following statements is true?

Consider this rxn which has a Δ G ° = +0.4 kJ\mol. A + B ↔ C + D 1 M A, 1 M B, 0.1 M C and 0.1 M D are added to a container at room temperature. Which of the following statements is true?

Which of the following is not true concerning standard states?

An isolated system can exchange ______ with its surroundings

Which of the following statements apply to anabolism?

Consider this rxn which has a Δ G ° = +0.4 kJ\mol. Succinate + FAD ↔ fumarate + FADH2 1 mM of each compound are mixed & the reaction is allowed to come to equilibrium. Which statement is correct about the resulting concentration of FAD at equilibrium?

The standard state usually used in biochemistry ( Δ G ° ') includes

Consider this rxn which has a Δ G ° = +0.4 kJ\mol. Succinate + FAD ↔ fumarate + FADH₂ 1 mM of each compound are mixed & the reaction is allowed to come to equilibrium. Which statement is correct about the resulting concentration of FAD at equilibrium?