Question 1

Which of the following best describes the role of ATP in cellular metabolism?

Accepted Answer

ATP provides energy for endergonic reactions by transferring a phosphate group to other molecules.

Question 2

According to the second law of thermodynamics, which of the following statements is true?

Accepted Answer

Every energy transfer or transformation increases the entropy of the universe.

Question 3

A chemical reaction has a $$\Delta G of$$ $$-7.3$$ kcal/mol. Which of the following is true about this reaction?

Accepted Answer

It is exergonic and will proceed spontaneously.

Question 4

Which of the following best explains why enzymes are highly specific for their substrates?

Accepted Answer

The active site of an enzyme forms many weak interactions with specific chemical groups of the substrate.

Question 5

Which of the following is an example of energy coupling in cells?

Accepted Answer

Using the energy released from ATP hydrolysis to drive the synthesis of glutamine from glutamic acid and ammonia.

Question 6

A scientist measures the change in free energy ($$\Delta G) $$for a reaction and finds it to be positive. What does this indicate about the reaction?

Accepted Answer

The reaction is endergonic and requires an input of energy.

Question 7

Which of the following best describes the effect of an enzyme on the activation energy ($$E_a) of a $$reaction?

Accepted Answer

Enzymes lower the activation energy, allowing reactions to proceed faster.

Question 8

Which of the following scenarios illustrates the first law of thermodynamics?

Accepted Answer

A plant converts light energy into chemical energy during photosynthesis.

Question 9

If the temperature of a system increases, what is the most likely effect on the entropy ($$S) of $$the system?

Accepted Answer

Entropy will increase because molecular motion becomes more random.

Question 10

Which of the following is true about catabolic pathways?

Accepted Answer

They release energy by breaking down complex molecules into simpler compounds.

Question 11

A reaction has $$\Delta H = -10$$ kcal/mol, $$T = 298 K$$, and $$\Delta S = -0.02$$ kcal/(mol\cdot K). What is $$\Delta G$$ for this reaction?

Accepted Answer

$$\Delta G = -10 - (298 	imes -0.02) = -4.04$$ kcal/mol

Question 12

Which of the following best explains why ATP hydrolysis is highly exergonic?

Accepted Answer

The products (ADP and Pi) have lower free energy than ATP due to relief of repulsion between phosphate groups.

Question 13

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

Accepted Answer

Covalently bonding to the substrate to form a permanent complex.

Question 14

Which of the following statements about enzyme activity is correct?

Accepted Answer

Each enzyme has an optimal temperature and pH at which it functions best.

Question 15

Which of the following best describes the difference between competitive and noncompetitive enzyme inhibitors?

Accepted Answer

Competitive inhibitors bind to the active site, while noncompetitive inhibitors bind to a different site on the enzyme.

Question 16

Which of the following is an example of feedback inhibition in metabolic pathways?

Accepted Answer

The end product of a pathway inhibits an enzyme that acts early in the pathway.

Question 17

Which of the following statements about the localization of enzymes within a cell is true?

Accepted Answer

Enzymes are often organized into complexes or located in specific organelles to increase metabolic efficiency.

Question 18

Which of the following best describes the relationship between free energy ($$\Delta G$$), enthalpy ($$\Delta H$$), entropy ($$\Delta S$$), and temperature ($$T$$)?

Accepted Answer

$$\Delta G = \Delta H - T\Delta S$$

Question 19

Which of the following is a correct statement about spontaneous reactions?

Accepted Answer

Spontaneous reactions have a negative $$\Delta G$$ and can occur without energy input.

Chapter 6: An Introduction to Metabolism – Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards