Chapter 6 Test File Questions

1.

The sum total of all the chemical reactions in a living structure is called its:

Explanation
Metabolism refers to the sum total of all the chemical reactions that occur within a living structure. It includes processes such as the conversion of food into energy, the synthesis of molecules, and the breakdown of waste products. Metabolism is essential for maintaining the life and functioning of an organism, as it provides the necessary energy and building blocks for growth, repair, and reproduction.

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2.

Water held back by a dam represents what kind of energy?

Explanation
When water is held back by a dam, it possesses potential energy. This is because the water is at a higher position and has the potential to do work or generate power. The potential energy is stored in the water due to its position relative to the ground. When the dam is opened or the water is released, this potential energy can be converted into other forms such as kinetic energy or electrical energy.

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3.

What can never be created or destroyed?

Explanation
Energy is a fundamental concept in physics, based on the principle of conservation of energy. It states that energy cannot be created or destroyed, but it can only be transferred or transformed from one form to another. This principle holds true in all natural processes, where the total amount of energy remains constant. Therefore, energy is something that cannot be created or destroyed, making it the correct answer to the question.

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4.

Which of the following represents potential energy?

A.

A. Chemical bonds
B.

B. Concentration gradient
C.

C. Electric charge imbalance
D.

D. Both a and b
E.

E. All of the above

Correct Answer
E. E. All of the above

Explanation
Potential energy is the energy that an object possesses due to its position or condition. In this case, all of the options listed represent different forms of potential energy. Chemical bonds store potential energy because breaking them releases energy, while forming them requires energy. A concentration gradient represents potential energy because it can drive the movement of substances from an area of high concentration to an area of low concentration. An electric charge imbalance represents potential energy because it can be used to do work or create an electric current. Therefore, all of the options listed represent potential energy.

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5.

The first law of thermodynamics states that the total energy in the universe is

Correct Answer
constant

Explanation
The first law of thermodynamics, also known as the law of conservation of energy, states that energy cannot be created or destroyed in an isolated system. It can only be transferred or transformed from one form to another. Therefore, the total energy in the universe remains constant over time. This principle is fundamental in understanding various energy transformations and the behavior of systems in thermodynamics.

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6.

In any system, the total energy includes usable and unusable energy. The unusable energy is a measure of the disorder of the system and is referred to as

Correct Answer
enthropy

Explanation
Entropy is a measure of the disorder or randomness in a system. In any system, there is both usable and unusable energy. The unusable energy, or entropy, increases as the disorder of the system increases. This means that as the system becomes more disordered, the amount of usable energy decreases. Therefore, entropy is a measure of the unusable energy or disorder in a system.

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7.

A change in free energy is related to a change in

A.

Temperature
B.

Enthropy
C.

Both

Correct Answer
C. Both

Explanation
A change in free energy is related to a change in temperature and entropy. Temperature affects free energy through the equation ΔG = ΔH - TΔS, where ΔG is the change in free energy, ΔH is the change in enthalpy, T is the temperature in Kelvin, and ΔS is the change in entropy. As temperature increases, the free energy change becomes more influenced by entropy. Therefore, both temperature and entropy play a role in determining the change in free energy.

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8.

If G of a chemical reaction is negative and the change in entropy is positive, you can conclude that the reaction is

Correct Answer
exergonic.

Explanation
If the ΔG (change in Gibbs free energy) of a chemical reaction is negative, it indicates that the reaction is spontaneous and can occur without the input of external energy. Additionally, if the change in entropy is positive, it implies that the system becomes more disordered during the reaction. Therefore, when both ΔG is negative and the change in entropy is positive, it can be concluded that the reaction is exergonic, meaning it releases energy.

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9.

The standard free energy change for the hydrolysis of ATP to ADP + Pi is –7.3 kcal/mol. From this information one can conclude that the reaction is

Correct Answer
exergonic.

Explanation
The standard free energy change for a reaction indicates whether the reaction is exergonic or endergonic. A negative value for the standard free energy change indicates that the reaction is exergonic, meaning it releases energy. In this case, the standard free energy change for the hydrolysis of ATP to ADP + Pi is -7.3 kcal/mol, which is a negative value. Therefore, one can conclude that the reaction is exergonic.

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10.

Chemical equilibrium is a state in which G =

Correct Answer
0

Explanation
Chemical equilibrium is a state in which the Gibbs free energy change (ΔG) is zero. This means that the forward and reverse reactions are occurring at the same rate, resulting in a balance between the reactants and products. At equilibrium, there is no net change in the concentrations of the reactants and products, and the system is considered stable. A ΔG value of zero indicates that the system is at equilibrium and there is no driving force for the reaction to proceed in either direction.

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11.

When ADP gains a phosphate to form ATP, energy is

Correct Answer
consumed

Explanation
When ADP gains a phosphate to form ATP, energy is consumed. This is because the process of phosphorylation, where a phosphate group is added to ADP to form ATP, requires energy input. The energy is derived from various sources such as the breakdown of glucose during cellular respiration or the absorption of light during photosynthesis. ATP serves as the primary energy currency in cells and is used to fuel various cellular processes, including muscle contraction, active transport, and synthesis of macromolecules.

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12.

If the enzyme phosphohexosisomerase is added to a 0.3 M solution of fructose 6-phosphate, and the reaction is allowed to proceed to equilibrium, the final concentrations are 0.2 M glucose 6-phosphate and 0.1 M fructose 6-phosphate. These data give an equilibrium constant of 2. What is the equilibrium constant if the initial concentration of fructose 6-phosphate is 3 M?

Correct Answer
2

Explanation
The equilibrium constant is a measure of the ratio of products to reactants at equilibrium. In this case, the reaction is converting fructose 6-phosphate into glucose 6-phosphate. The initial concentration of fructose 6-phosphate is 3 M, and at equilibrium, the concentration of fructose 6-phosphate is 0.1 M. This means that the reaction has consumed 2.9 M of fructose 6-phosphate. The concentration of glucose 6-phosphate at equilibrium is 0.2 M. Therefore, the ratio of products to reactants at equilibrium is 0.2/2.9, which simplifies to 2/29. Thus, the equilibrium constant is 2/29.

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