Question 1

Which of the following best describes the First Law of Thermodynamics as it applies to biological systems?

Accepted Answer

Energy is transformed from one form to another, but the total amount remains constant.

Question 2

A diver climbs up a platform and then jumps into the water. Which energy transformations occur during this process?

Accepted Answer

Kinetic energy is converted to potential energy while climbing, and potential energy is converted to kinetic energy while diving.

Question 3

Which of the following bonds has the highest potential energy according to the diagram of C-H, N-H, and O-H bonds?

Accepted Answer

C-H bond

Question 4

Which statement about exergonic and endergonic reactions is correct?

Accepted Answer

Exergonic reactions release energy and have $$\Delta G \u003c 0.$$

Question 5

During exercise, your body heats up. Which energy transformation is primarily responsible for this increase in temperature?

Accepted Answer

Kinetic energy is converted to thermal energy.

Question 6

Which of the following best explains energetic coupling in cells?

Accepted Answer

It allows endergonic reactions to proceed by using the energy released from exergonic reactions.

Question 7

In a redox reaction, what happens when a molecule is reduced?

Accepted Answer

It gains electrons and often gains potential energy.

Question 8

ATP hydrolysis releases energy that can be used to drive endergonic reactions. What is the standard free energy change ($$\Delta G) $$for ATP hydrolysis?

Accepted Answer

$$\Delta G = -7.3$$ kcal/mol

Question 9

Which of the following is NOT a way that enzymes lower the activation energy of a reaction?

Accepted Answer

Increasing the free energy change ($$\Delta G) of $$the reaction.

Question 10

A scientist is studying an enzyme that works best at pH 2. What is most likely true about this enzyme?

Accepted Answer

It is likely from a human stomach cell.

Question 11

Which of the following best describes competitive inhibition of an enzyme?

Accepted Answer

A molecule binds to the active site, preventing the substrate from binding.

Question 12

What is the main purpose of feedback inhibition in a metabolic pathway?

Accepted Answer

To prevent the accumulation of unnecessary products by inhibiting an early enzyme in the pathway.

Question 13

Which of the following statements about enzyme regulation is correct?

Accepted Answer

Phosphorylation can either activate or inactivate an enzyme.

Question 14

A metabolic pathway is regulated by feedback inhibition. If the final product accumulates, what will happen to the activity of the first enzyme in the pathway?

Accepted Answer

The activity of the first enzyme will decrease.

Question 15

Which of the following best explains why enzymes are necessary for life?

Accepted Answer

They allow reactions to occur at rates fast enough to sustain life.

Question 16

Which of the following is an example of energetic coupling in a cell?

Accepted Answer

The use of ATP hydrolysis to drive the synthesis of glucose from CO$$_2$$ and H$$_2O.$$

Question 17

Which of the following statements about redox reactions is correct?

Accepted Answer

Oxidation is the loss of electrons, and reduction is the gain of electrons.

Question 18

Which of the following factors does NOT affect enzyme activity?

Accepted Answer

The color of the enzyme

Question 19

A mutation causes an enzyme's active site to change shape. Which of the following is the most likely result?

Accepted Answer

The enzyme will no longer bind its substrate effectively.

Question 20

Which of the following best describes the effect of an enzyme on the activation energy ($$E_a) $$and the free energy change ($$\Delta G) of a $$reaction?

Accepted Answer

An enzyme lowers $$E_a$$ but does not change $$\Delta G.$$

Energy and Enzymes: Foundations of Cellular Metabolism

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