Question 1

Which of the following best describes the difference between catabolic and anabolic pathways in cellular metabolism?

Accepted Answer

Catabolic pathways release energy by breaking down complex molecules, while anabolic pathways consume energy to build complex molecules.

Question 2

Which equation correctly represents the change in free energy ($$\Delta G) $$for a chemical reaction?

Accepted Answer

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

Question 3

Why is an organism considered an open system?

Accepted Answer

It exchanges both energy and matter with its surroundings.

Question 4

Which statement best summarizes the second law of thermodynamics as it applies to biological systems?

Accepted Answer

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

Question 5

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

Accepted Answer

It is an exergonic reaction and occurs spontaneously.

Question 6

Which of the following best describes how ATP powers cellular work?

Accepted Answer

ATP hydrolysis is coupled to endergonic reactions, often by phosphorylation of a reactant.

Question 7

Which of the following is NOT a way that enzymes lower the activation energy ($$E_A) of a $$reaction?

Accepted Answer

Supplying heat to the reaction.

Question 8

Which of the following statements about enzyme specificity is correct?

Accepted Answer

Enzyme specificity results from the complementary fit between the enzyme's active site and the substrate.

Question 9

A competitive inhibitor decreases the rate of an enzyme-catalyzed reaction by:

Accepted Answer

Competing with the substrate for binding at the active site.

Question 10

Which of the following best explains why increasing substrate concentration can overcome competitive inhibition but not noncompetitive inhibition?

Accepted Answer

Competitive inhibitors bind to the active site, so more substrate can outcompete them; noncompetitive inhibitors bind elsewhere and change enzyme shape.

Question 11

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

Accepted Answer

The end product of a pathway binds to an enzyme early in the pathway, decreasing its activity.

Question 12

Which of the following best describes the induced-fit model of enzyme function?

Accepted Answer

The enzyme changes shape slightly to fit more snugly around the substrate upon binding.

Question 13

Which of the following environmental factors can affect enzyme activity?

Accepted Answer

Both temperature and pH, as well as cofactors and inhibitors.

Question 14

Which of the following statements about the ATP cycle is correct?

Accepted Answer

ATP is regenerated from ADP and inorganic phosphate using energy from catabolic reactions.

Question 15

Which of the following is true about the relationship between free energy, stability, and equilibrium?

Accepted Answer

A spontaneous process moves a system toward equilibrium, decreasing free energy and increasing stability.

Question 16

Which of the following is a correct description of an allosteric enzyme?

Accepted Answer

An enzyme whose activity can be regulated by the binding of a molecule at a site other than the active site.

Question 17

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

Accepted Answer

The repulsion between the negatively charged phosphate groups is relieved when ATP is hydrolyzed.

Question 18

Which of the following is an example of cooperativity in enzyme regulation?

Accepted Answer

The binding of one oxygen molecule to hemoglobin increases the affinity for additional oxygen molecules.

Question 19

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

Accepted Answer

Exergonic reactions have a negative $$\Delta G$$ and release energy.

Question 20

A scientist is studying an enzyme-catalyzed reaction. She increases the substrate concentration and observes that the reaction rate increases, but then levels off even with further increases in substrate. What is the most likely explanation?

Accepted Answer

The enzyme is saturated; all active sites are occupied.

Chapter 8: An Introduction to Metabolism – General Biology Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard