Question 1

Which of the following types of reactions would decrease the entropy within a cell?
A) anabolic reactions
B) hydrolysis
C) digestion
D) catabolic reactions

Accepted Answer

Anabolic reactions build larger molecules from smaller ones, so they would decrease the entropy within a cell. Hydrolysis and digestion involve breaking down larger molecules into smaller ones, which would increase entropy. Catabolic reactions also break down molecules, but they usually release energy and increase entropy in the process.

Question 2

Which of the following is an example of potential rather than kinetic energy?
A) Water rushing over Niagara Falls.
B) Light flashes emitted by a firefly.
C) A molecule of glucose.
D) A crawling beetle foraging for food.

Accepted Answer

Kinetic energy is energy of motion while potential energy is stored energy. Water rushing over Niagara Falls, light flashes emitted by a firefly, and a crawling beetle foraging for food are all examples of kinetic energy because they all involve motion. However, a molecule of glucose represents potential energy because it has stored energy that can be released through chemical reactions.

Question 3

Which of the following statements about anabolic pathways is true?
A) They are usually spontaneous chemical reactions.
B) They consume energy to build up polymers from monomers.
C) They release energy by degrading polymers to monomers.
D) They decrease the entropy of the organism and its environment.

Accepted Answer

Anabolic pathways consume energy to build up polymers from monomers. This is in contrast to catabolic pathways, which release energy by degrading polymers to monomers. Anabolic pathways also typically require enzymes to catalyze the reaction and are not usually spontaneous. They may increase the order or decrease the entropy of the organism and its environment.

Question 4

Which of the following statements describes the first law of thermodynamics?
A) Energy cannot be created or destroyed.
B) The entropy of the universe is decreasing.
C) The entropy of the universe is constant.
D) Energy cannot be transferred or transformed.

Accepted Answer

The first law of thermodynamics, also known as the law of conservation of energy, states that energy cannot be created or destroyed, only transferred or transformed from one form to another.

Question 5

Which of the following statements is true for a system at chemical equilibrium?
A) The system consumes energy at a steady rate.
B) The system releases energy at a steady rate.
C) The kinetic energy of the system is zero.
D) The system can do no work.

Accepted Answer

At chemical equilibrium, the forward and reverse reactions occur at equal rates, so there is no net change in the system. Therefore, the system cannot do work. In addition, the kinetic energy of the particles in the system is not necessarily zero, as they are still in motion, and there is no consumption or release of energy at a steady rate.

Question 6

Chemical equilibrium is relatively rare in living cells because metabolic pathways are interconnected. Which of the following statements describes an example of a reaction that may be at chemical equilibrium in a cell?
A) An exergonic reaction in which the free energy at equilibrium is higher than the energy content of the reaction at any point away from equilibrium.
B) An exergonic reaction in which the entropy change in the cell is precisely balanced by an opposite entropy change in the cell's surroundings.
C) A chemical reaction in which neither the reactants nor the products are being produced or consumed in any metabolic pathway at that time in the cell.
D) An endergonic reaction in an active metabolic pathway where the energy for that reaction is supplied only by heat from the environment.

Accepted Answer

Chemical equilibrium is a state in which the forward and reverse reactions occur at equal rates, meaning that the concentrations of reactants and products remain constant over time. In a living cell, metabolic pathways are interconnected, so reactions are continuously being catalyzed in different directions. This prevents many reactions from reaching equilibrium. However, there may be some reactions in the cell that are not being actively produced or consumed by any metabolic pathway at a given time, allowing them to reach equilibrium. In this scenario, neither the reactants nor the products are being preferentially produced or consumed, so the concentrations of both remain constant. Thus, option C is the correct choice.

Question 7

A decrease in entropy is associated with which type of reaction?
A) dehydration
B) catabolic
C) depolymerisation
D) hydrolysis

Accepted Answer

A decrease in entropy is associated with a reaction that decreases the number of available microstates or arrangements of molecules. Dehydration reactions involve the removal of a molecule of water, which can decrease the number of available microstates and lead to a decrease in entropy.

Question 8

Which of the following terms most precisely describes the cellular process of breaking down large molecules into smaller ones?
A) catabolism (catabolic pathways)
B) metabolism
C) anabolism (anabolic pathways)
D) dehydration

Accepted Answer

Catabolism specifically refers to the process of breaking down large molecules into smaller ones, while metabolism encompasses all chemical processes in an organism. Anabolism refers to the process of building larger molecules from smaller ones, and dehydration refers specifically to the removal of water molecules.

Question 9

Which of the following statements is true of metabolism in its entirety in all organisms?
A) Metabolism depends on a constant supply of energy from food.
B) Metabolism uses all of an organism's resources.
C) Metabolism consists of all the energy transformation reactions in an organism.
D) Metabolism manages the increase of entropy in an organism.

Accepted Answer

Metabolism consists of all the energy transformation reactions in an organism. It includes anabolism (the buildup of molecules) and catabolism (the breakdown of molecules) as well as all the other biochemical reactions that occur within an organism. While energy from food is certainly important for metabolism, it is not the only aspect of it. Additionally, metabolism does not necessarily use all of an organism's resources, and although it does manage entropy, that is not the primary definition of metabolism.

Question 10

Why do hydrolysis reactions occur more readily in solution than dehydration reactions?
A) Hydrolysis reactions increase G, or Gibbs free energy of the system.
B) Hydrolysis reactions are endergonic and increase entropy of the system.
C) Hydrolysis reactions are exergonic and decrease entropy of the system.
D) Hydrolysis reactions are exergonic and increase entropy of the system.

Accepted Answer

Hydrolysis reactions involve the addition of water molecules to break down molecules into smaller components, resulting in an increase in entropy of the system. This makes hydrolysis reactions exergonic and more energetically favorable in solution. In contrast, dehydration reactions involve the removal of water molecules to link smaller molecules together, resulting in a decrease in entropy of the system. This makes dehydration reactions endergonic and less energetically favorable in solution.

Question 11

Which of the following statements is true for all exergonic reactions?
A) The products have more total energy than the reactants.
B) The reaction proceeds with a net release of free energy.
C) The reaction goes only in a forward direction: all reactants will be converted to products, but no products will be converted to reactants.
D) A net input of energy from the surroundings is required for the reactions to proceed.

Accepted Answer

Exergonic reactions are those that release energy, usually in the form of heat or light. This means that the products have less total energy than the reactants, and the reaction proceeds with a net release of free energy. Unlike endergonic reactions, exergonic reactions do not require a net input of energy from the surroundings to proceed. While some exergonic reactions may be reversible, many do proceed only in the forward direction.

Question 12

A chemical reaction that has a positive ΔG is best described as ________.
A) endergonic
B) enthalpic
C) spontaneous
D) exergonic

Accepted Answer

A positive ΔG means the reaction requires input of energy to proceed, which is characteristic of endergonic reactions.

Question 13

The mathematical expression for the change in free energy of a system is ΔG = ΔH - TΔS. Which of the following statements is correct?
A) ΔS is the change in enthalpy, a measure of randomness.
B) ΔH is the change in entropy, the energy available to do work.
C) ΔG is the change in free energy.
D) T is the temperature in degrees Celsius.

Accepted Answer

ΔG is the change in free energy, which is a measure of the energy available to do useful work. ΔH is the change in enthalpy (not entropy), which is a measure of the total heat content of a system. ΔS is the change in entropy, which is a measure of the randomness or disorder of the system. T is the temperature in Kelvin, not degrees Celsius.

Question 14

Most cells cannot harness heat to perform work because ________.
A) heat is not a form of energy
B) temperature is usually uniform throughout a cell
C) heat can never be used to do work
D) heat must remain constant during work

Accepted Answer

Temperature is usually uniform throughout a cell, so there is no temperature gradient that can be harnessed to perform work. Heat is a form of energy, but it cannot be used to do work unless there is a difference in temperature that can be exploited. Heat does not need to remain constant during work, but there must be a difference in heat energy between two points.

Question 15

Which of the following statements is consistent with the second law of thermodynamics?
A) A gain of free energy in a system is always associated with conversion of energy from one form to another.
B) A constant input of energy is required to maintain the high level of cellular organisation.
C) Without an input of energy, the entropy of an organism would tend to decrease over time.
D) Every energy transformation performed by an organism decreases the entropy of the universe.

Accepted Answer

The second law of thermodynamics states that entropy (the degree of disorder in a system) tends to increase over time, unless energy is added to the system. Option B is consistent with this law because it states that a constant input of energy is necessary to maintain the high level of organisation in cells, which represents a decrease in entropy. The other options do not accurately reflect the second law. Option A is incorrect as free energy can also be lost during conversion. Option C is incorrect as without an input of energy, the entropy would tend to increase in an organism rather than decrease. Option D is incorrect as every energy transformation increases the entropy of the universe.

Question 16

Living organisms increase in complexity as they grow, resulting in a decrease in the entropy of an organism. How does this relate to the second law of thermodynamics?
A) Living organisms do not obey the second law of thermodynamics, which states that the entropy of an organism increases with each energy transformation.
B) The decrease in entropy is associated with growth of an organism. As a consequence of growth, organisms cause a greater increase in entropy in their environment than the decrease in entropy associated with their increased complexity.
C) As a consequence of growth, the decrease in entropy of the organism is associated with a corresponding decrease in the entropy of the universe.
D) Living organisms are able to transform chemical energy into entropy.

Accepted Answer

The second law of thermodynamics states that the total entropy of a closed system will always increase over time. However, living organisms are open systems that are able to increase in complexity (a decrease in entropy) by taking in energy and matter from their environment. However, in the process of growth and metabolism, organisms create a greater increase in entropy in their environment than the decrease in entropy associated with their increased complexity. Therefore, the decrease in entropy in an organism is offset by an increase in the total entropy of the system including the organism and its environment. This interpretation of the second law is sometimes called the entropy principle or the maximum entropy production principle.

Question 17

Which of the following statements is a logical consequence of the second law of thermodynamics?
A) If the entropy of a system increases, there must be a corresponding decrease in the entropy of the universe.
B) If the entropy of a system decreases, there must be a corresponding decrease in the entropy of the universe.
C) If there is an increase in the energy of a system, there must be a corresponding decrease in the energy of the rest of the universe.
D) Each chemical reaction in an organism must increase the total entropy of the universe.

Accepted Answer

The answer of Which of the following statements is a...

Question 18

Which of the following statements about the evolution of life on Earth, from simple prokaryote-like cells to multicellular eukaryotic organisms, is true?
A) By resulting in such diversity and complexity of life, it is an exception to the second law of thermodynamics.
B) It has occurred in accordance with the laws of thermodynamics and resulted in a substantial increase in the entropy of the planet.
C) It has occurred in accordance with the laws of thermodynamics and resulted in a substantial increase in the total energy in the universe.
D) It has occurred in accordance with the laws of thermodynamics and resulted in a substantial decrease in the entropy of the planet.

Accepted Answer

The answer of Which of the following statements about the...

Question 19

Which of the following statements is an important consequence of the first law of thermodynamics for a living organism?
A) The energy content of an organism is constant.
B) An organism ultimately must obtain all of the necessary energy for life from its environment.
C) The entropy of an organism decreases with time as the organism grows in complexity.
D) Organisms grow by converting energy into organic matter.

Accepted Answer

The answer of Which of the following statements is an...

Question 20

The relationship between catabolism and anabolism is most similar to the relationship between which of the following pairs of terms?
A) exergonic; spontaneous
B) exergonic; endergonic
C) free energy; entropy
D) work; free energy

Accepted Answer

Catabolism and anabolism are both involved in metabolic pathways, with catabolism breaking down molecules and releasing energy, while anabolism builds molecules and requires energy. This is similar to the relationship between exergonic reactions (releases energy) and endergonic reactions (require energy).

Quiz 8: An Introduction to Metabolism

Which of the following types of reactions would decrease the entropy within a cell?

Which of the following is an example of potential rather than kinetic energy?

Which of the following statements about anabolic pathways is true?

Which of the following statements describes the first law of thermodynamics?

Which of the following statements is true for a system at chemical equilibrium?

Chemical equilibrium is relatively rare in living cells because metabolic pathways are interconnected. Which of the following statements describes an example of a reaction that may be at chemical equilibrium in a cell?

A decrease in entropy is associated with which type of reaction?

Which of the following terms most precisely describes the cellular process of breaking down large molecules into smaller ones?

Which of the following statements is true of metabolism in its entirety in all organisms?

Why do hydrolysis reactions occur more readily in solution than dehydration reactions?

Which of the following statements is true for all exergonic reactions?

A chemical reaction that has a positive ΔG is best described as ________.

The mathematical expression for the change in free energy of a system is ΔG = ΔH - TΔS. Which of the following statements is correct?

Most cells cannot harness heat to perform work because ________.

Which of the following statements is consistent with the second law of thermodynamics?

Living organisms increase in complexity as they grow, resulting in a decrease in the entropy of an organism. How does this relate to the second law of thermodynamics?

Which of the following statements is a logical consequence of the second law of thermodynamics?

Which of the following statements about the evolution of life on Earth, from simple prokaryote-like cells to multicellular eukaryotic organisms, is true?

Which of the following statements is an important consequence of the first law of thermodynamics for a living organism?

The relationship between catabolism and anabolism is most similar to the relationship between which of the following pairs of terms?