Q: Which of the following equations correctly represents the change in free energy ($$\Delta G) $$for a chemical reaction?

$$\Delta G = (\text{free energy of products}) - (\text{free energy of reactants})$$

Question 1

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

Accepted Answer

Anabolic pathways build complex molecules from simpler ones, requiring energy input, while catabolic pathways break down complex molecules into simpler ones, releasing energy.

Question 2

A grizzly bear catches a fish and eats it before running away. Which sequence best describes the energy transformations that occur in this scenario?

Accepted Answer

Chemical energy in the fish is converted to kinetic energy as the bear runs, and some is lost as heat (thermal energy).

Question 3

Which statement correctly applies the second law of thermodynamics to biological systems?

Accepted Answer

Every energy transformation in cells increases the entropy of the universe, often by releasing heat.

Question 4

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

Accepted Answer

$$\Delta G = (	ext{free energy of products}) - (	ext{free energy of reactants})$$

Question 5

Cellular respiration is the process by which glucose ($$\mathrm{C_6H_{12}O_6$}) $$and oxygen ($$\mathrm{O_2$}) $$are converted to carbon dioxide ($$\mathrm{CO_2$}) $$and water ($$\mathrm{H_2O}$$), releasing energy. Which of the following best describes this process?

Accepted Answer

It is a spontaneous, exergonic reaction.

Question 6

Which of the following statements about ATP is correct?

Accepted Answer

ATP releases energy when one of its phosphate groups is removed by hydrolysis.

Question 7

How does ATP couple exergonic and endergonic reactions in cells?

Accepted Answer

ATP hydrolysis releases energy (exergonic), which is used to drive endergonic reactions.

Question 8

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

Accepted Answer

Enzymes undergo an induced fit, slightly changing shape to optimally bind specific substrates.

Question 9

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

Accepted Answer

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

Question 10

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 as more substrate is added. What is the most likely explanation?

Accepted Answer

All enzyme active sites are saturated with substrate, so the reaction rate cannot increase further.

Question 11

Which of the following best describes the effect of temperature on enzyme activity?

Accepted Answer

Enzyme activity is highest at an optimal temperature, but decreases at temperatures above this due to denaturation.

Question 12

Which of the following statements about enzyme cofactors is correct?

Accepted Answer

Cofactors are non-protein helpers; coenzymes are organic cofactors, often derived from vitamins.

Question 13

A competitive inhibitor affects an enzyme-catalyzed reaction by:

Accepted Answer

Competing with the substrate for binding at the enzyme's active site.

Question 14

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

Accepted Answer

A product of the pathway binds to an enzyme early in the pathway, decreasing its activity.

Question 15

Which of the following best explains why cells are considered open systems in terms of thermodynamics?

Accepted Answer

Cells constantly exchange energy and matter with their surroundings, preventing equilibrium.

Question 16

Which of the following is true regarding the effect of pH on enzyme activity?

Accepted Answer

Each enzyme has an optimal pH at which its activity is highest.

Question 17

Which of the following best describes an exergonic reaction?

Accepted Answer

A reaction that releases energy and has $$\Delta G \u003c 0.$$

Question 18

Which of the following is a real-life example of a noncompetitive inhibitor?

Accepted Answer

A heavy metal ion binding to a site other than the active site, altering enzyme shape and function.

Question 19

Which of the following statements about the role of enzymes in metabolic pathways is correct?

Accepted Answer

Each step in a metabolic pathway is catalyzed by a specific enzyme.

Question 20

Which of the following best explains why the diffusion of a substance across a membrane is consistent with the second law of thermodynamics?

Accepted Answer

Diffusion increases the entropy (disorder) of the system as molecules spread out.

Chapter 8: An Introduction to Metabolism – Study Guide and Lecture Outline

Guida di studio - Domande di pratica

Study guide - Flashcard