Question 1

Which of the following best describes the first law of thermodynamics as it applies to living organisms?

Accepted Answer

Energy is transferred and transformed, but the total amount remains constant.

Question 2

A bear eats a fish, but only a portion of the energy from the fish is available for the bear to use. According to the second law of thermodynamics, what happens to the rest of the energy?

Accepted Answer

It is converted into heat and increases the entropy of the universe.

Question 3

Which equation is used to calculate the change in free energy ($$\Delta G) of a $$chemical reaction?

Accepted Answer

$$\Delta G = G_{products} - G_{reactants}$$

Question 4

A chemical reaction in a cell has a $$\Delta G of$$ $$-123 kJ/$$mol. What does this indicate about the reaction?

Accepted Answer

The reaction is spontaneous and releases energy.

Question 5

Which of the following is an example of potential energy in biological systems?

Accepted Answer

The energy stored in the chemical bonds of glucose.

Question 6

Why do spontaneous chemical reactions tend to increase entropy?

Accepted Answer

Because they release energy and increase disorder in the environment.

Question 7

Which statement best explains why not all energy from food is available for cellular work?

Accepted Answer

Some energy is lost as heat, increasing the entropy of the universe.

Question 8

If a reaction has a positive $$\Delta G$$, what can be concluded about the reaction?

Accepted Answer

It is nonspontaneous and requires energy input.

Question 9

Which of the following best describes an open system in biology?

Accepted Answer

A system that exchanges both energy and matter with its surroundings.

Question 10

Which of the following substances is commonly used by living organisms as a source of chemical potential energy?

Accepted Answer

Glucose ($$C_6H_{12}O_6$)

Question 11

Which process in cells is an example of energy coupling?

Accepted Answer

Using ATP hydrolysis to drive an endergonic reaction.

Question 12

A scientist measures the free energy change of a reaction and finds $$\Delta G = 0. $$What does this mean?

Accepted Answer

The reaction is at equilibrium.

Question 13

Which of the following best explains why metabolic pathways are composed of many different reactions?

Accepted Answer

To allow for the controlled release and use of energy.

Question 14

Which of the following is true about ATP hydrolysis in cells?

Accepted Answer

It releases free energy that can be used to do cellular work.

Question 15

Which of the following reactions is most likely to occur spontaneously?

Accepted Answer

A reaction with $$\Delta G = -50 kJ/$$mol

Question 16

Which statement best describes the role of entropy in biological systems?

Accepted Answer

Entropy measures the disorder or randomness in a system.

Question 17

A cell needs to perform an endergonic reaction. Which strategy will it most likely use?

Accepted Answer

Couple the reaction with ATP hydrolysis to provide the necessary energy.

Question 18

Which of the following is a correct statement about exergonic and endergonic reactions?

Accepted Answer

Exergonic reactions release energy; endergonic reactions require energy input.

Question 19

Which of the following best explains why cells must regulate spontaneous chemical reactions?

Accepted Answer

To prevent the loss of all energy as heat and ensure energy is harnessed for cellular work.

Question 20

A metabolic pathway involves several reactions, some exergonic and some endergonic. What is the overall effect of coupling these reactions?

Accepted Answer

It allows the cell to drive endergonic reactions using energy released from exergonic reactions.

Energy, Thermodynamics, and Chemical Reactions in Biology

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