Question 1

By definition, a spontaneous reaction is one in which
A) energy is released.
B) energy is absorbed.
C) the energy change is zero.
D) the reaction happens quickly
E) energy is released and the reaction happens quickly

Accepted Answer

A spontaneous reaction is one in which the products have less free energy than the reactants, resulting in a release of energy. This energy can be in various forms such as heat, light, or sound. Therefore, option A is the correct choice.

Question 2

Which best describes the ΔG 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 ΔG° for the hydrolysis of creatine phosphate at 25°C is −43 kJ/mol.
A) ΔG < −43 kJ/mol
B) ΔG = −43 kJ/mol
C) −43 kJ/mol < ΔG ≤ 0 kJ/mol
D) ΔG > 0 kJ/mol

Accepted Answer

A

Question 3

Living things are _____
A) a closed system
B) an open system
C) an isolated system
D) none of these

Accepted Answer

Living things are open systems, meaning they exchange energy and matter with their environment. They take in nutrients and oxygen, and release waste products and carbon dioxide. This exchange allows for growth, reproduction, and the maintenance and repair of the organism.

Question 4

Consider this rxn which has a ΔG° = +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? A) [FAD] > [FADH₂] B) [FAD] < [FADH₂] C) [FAD] = [FADH₂] D) Cannot be determined from the information provided.

Accepted Answer

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

Question 5

An isolated system can exchange ______ with its surroundings
A) energy but not matter
B) matter but not energy
C) both matter and energy
D) neither matter nor energy

Accepted Answer

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

Question 6

In general, catabolism
A) releases energy.
B) absorbs energy.
C) neither absorbs nor releases energy.

Accepted Answer

Catabolism is the breakdown of complex molecules into simpler ones, which releases energy.

Question 7

Consider this rxn which has a ΔG° = +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?
A) ΔG < 0 (i.e., it's negative)
B) ΔG = 0
C) ΔG > 0 (i.e., it's positive)
D) Cannot be determined from the information provided.

Accepted Answer

The reaction quotient Q = [C][D]/[A][B] = (0.1)(0.1)/(1)(1) = 0.01. Since ΔG° is positive, the reaction is not spontaneous under standard conditions. However, because Q < K (where K is the equilibrium constant), the reaction will proceed forward to reach equilibrium, making ΔG negative.

Question 8

Consider this rxn which has a ΔG° = +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?
A) The reaction will proceed in the forward direction to reach equilibrium.
B) The reaction will proceed in the backward direction to reach equilibrium.
C) The reaction will not proceed in either direction; it is already at equilibrium.
D) Cannot be determined from the information provided.

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 9

A biological reaction with a significantly postive ΔG under cellular conditions may proceed in the forward direction because
A) The cell will change the concentrations of the substrates and products so that the reaction can occur
B) The cell will raise the temperature, thereby affecting the overall thermodynamics of the reaction
C) the reaction can be coupled to a reaction with a more significant negative ΔG
D) reactions with positive ΔG values always proceed in the forward direction
E) None of these

Accepted Answer

A reaction with a significantly positive ΔG can still proceed in the forward direction if it is coupled with a reaction that has a more significant negative ΔG. This occurs through a process known as coupling, which allows the energy released from the negative ΔG reaction to drive the positive ΔG reaction forward. Therefore, option C is the best choice. Option A is not always true since the cell may not always have the ability to change the concentrations of substrates and products. Option B is incorrect because raising temperature affects the rate of the reaction and not its thermodynamics. Option D is incorrect because some reactions with positive ΔG values may not proceed in the forward direction.

Question 10

I am performing a reaction, A → B, with ΔG°' = −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?
A) The reaction has reached equilibrium.
B) I should come back again later; equilibrium has not yet been reached.
C) The formation of B from A is thermodynamically unfavorable, so I should find another starting material to make B.
D) I must've screwed up; there's no way I could get that result with that ΔG°'

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 11

Biochemists use a modified value for standard ΔG values because
A) all reagents are not at a 1 molar concentration.
B) the pH in living systems is seldom, if ever, near 0.
C) the concentration of water is not at 1 molar concentration.
D) the reagents are not one molar and the pH = 7.
E) All of these justify why biochemists use a special ΔG value.

Accepted Answer

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

Question 12

Which of the following statements concerning the free energy change (ΔG) is false?
A) The energy change for a reaction depends only on the initial and final states, and is independent of the path taken.
B) The overall energy change for a reaction could be calculated by summing the energy changes for a series of separate reactions that could convert the reactants to the products.
C) The rate of a reaction can be determined from the energy change.
D) The energy change is a function of the concentrations of the products and reactants at start.
E) All of the answers are true

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 13

I am performing a reaction, A → B, with ΔG°' = −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?
A) The reaction has reached equilibrium.
B) I should come back again later; equilibrium has not yet been reached.
C) The formation of B from A is thermodynamically unfavorable, so I should find another starting material to make B.
D) I must've screwed up; there's no way I could get that result with that ΔG°'

Accepted Answer

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

Question 14

Which of the following statements apply to anabolism?
A) proceeds in stages
B) requires energy
C) requires reducing agents
D) all of these

Accepted Answer

Anabolism involves the synthesis of complex molecules from simple ones, and this process usually proceeds in stages. It requires energy in the form of ATP, and also requires reducing agents such as NADPH. Therefore, all of the statements A, B, and C apply to anabolism.

Question 15

The standard state usually used in biochemistry (ΔG°') includes A) all concentrations at 1 M. B) all concentrations at 1 M, except for [H⁺], which is 10−⁷ M. C) same as a), but at 25° C. D) same as b), but at 25° C. E) None of the answers

Accepted Answer

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

Question 16

Which of the following is not true concerning standard states?
A) For pure liquids, the standard state is 1M
B) For pure solids, the standard state is the pure solid itself
C) For gases, the standard state is 1 atmosphere
D) For solutes, the standard state is 1M
E) All of the answers are true

Accepted Answer

For pure liquids, the standard state is the pure liquid itself, not necessarily 1M.

Question 17

In general, catabolism
A) is an oxidative process that releases energy
B) is a reductive process that releases energy
C) is an oxidative process that requires energy
D) is a reductive process that requires energy
E) none of these

Accepted Answer

Catabolism involves the breakdown of molecules, and typically involves oxidation reactions that release energy. This energy is then used by the cell for various processes such as ATP synthesis.

Question 18

"Metabolism" refers to
A) the breakdown of larger molecules into smaller ones.
B) the production of larger molecules from smaller ones.
C) both of these
D) none of these

Accepted Answer

Metabolism refers to both the breakdown of larger molecules into smaller ones (catabolism) and the production of larger molecules from smaller ones (anabolism).

Question 19

The standard state of a solution is taken as
A) 1 atmosphere of pressure.
B) the pure solute.
C) 1 molar concentration.
D) 1 % by weight
E) none of the above.

Accepted Answer

The standard state of a solution is taken as 1 molar concentration. This is because molarity is a measure of the number of moles of solute per liter of solution, and is a way to standardize the concentration of a solution. 1 atmosphere of pressure (A) is the standard state for gases, while the pure solute (B) is not a standard state for a solution as it represents a non-existent scenario in most cases. 1% by weight (D) is a measure of the concentration of a solution but is not a standard state.

Question 20

The production of larger molecules from smaller ones is called
A) metabolism.
B) catabolism.
C) anabolism.
D) none of these

Accepted Answer

Anabolism is the process of building larger molecules from smaller ones, while catabolism is the process of breaking down larger molecules into smaller ones. Metabolism refers to all chemical reactions that occur in an organism, including both anabolism and catabolism. Therefore, choice C is the best answer as it specifically refers to the production of larger molecules from smaller ones.

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

By definition, a spontaneous reaction is one in which

Which best describes the ΔG 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 ΔG° for the hydrolysis of creatine phosphate at 25°C is −43 kJ/mol.

Living things are _____

Consider this rxn which has a ΔG° = +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?

An isolated system can exchange ______ with its surroundings

In general, catabolism

Consider this rxn which has a ΔG° = +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 ΔG° = +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?

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

Biochemists use a modified value for standard ΔG values because

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

Which of the following statements apply to anabolism?

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

Which of the following is not true concerning standard states?

In general, catabolism

"Metabolism" refers to

The standard state of a solution is taken as

The production of larger molecules from smaller ones is called

Consider this rxn which has a ΔG° = +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?