Question 1

Which of the following best describes the difference between kinetic and potential energy in biological systems?

Accepted Answer

Kinetic energy is the energy of motion, such as thermal energy, while potential energy is stored in the position or configuration of molecules, such as chemical energy in bonds.

Question 2

According to the first law of thermodynamics, which of the following statements is correct?

Accepted Answer

Energy is conserved; it cannot be created or destroyed, only transferred or transformed.

Question 3

A chemical reaction has a negative $$\Delta G. $$What does this indicate about the reaction?

Accepted Answer

The reaction is exergonic and will proceed spontaneously.

Question 4

Which equation correctly represents the standard free-energy change for a reaction?

Accepted Answer

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

Question 5

In the context of redox reactions, what does it mean if a molecule is reduced?

Accepted Answer

It has gained electrons, often accompanied by protons (H+).

Question 6

Which of the following best explains why ATP has a high potential energy?

Accepted Answer

It contains three phosphate groups with clustered negative charges that repel each other.

Question 7

What is the primary role of enzymes in biological systems?

Accepted Answer

They lower the activation energy required for reactions to proceed.

Question 8

A scientist increases the temperature and concentration of reactants in a chemical reaction. What is the most likely effect on the reaction rate?

Accepted Answer

The reaction rate will increase.

Question 9

Which of the following statements about enzyme saturation kinetics is correct?

Accepted Answer

At high substrate concentrations, the reaction rate plateaus because all enzyme active sites are occupied.

Question 10

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

Accepted Answer

The final product of the pathway binds to an enzyme early in the pathway, inhibiting its activity.

Question 11

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

Accepted Answer

Phosphorylation can either activate or deactivate enzymes by changing their shape.

Question 12

A competitive inhibitor affects an enzyme by:

Accepted Answer

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

Question 13

Which of the following is true about the relationship between exergonic and endergonic reactions in cells?

Accepted Answer

Exergonic reactions can drive endergonic reactions through energetic coupling.

Question 14

Which of the following best explains why enzymes are specific for particular reactions?

Accepted Answer

Enzymes have active sites with unique shapes that fit only specific substrates.

Question 15

Which of the following is NOT a way that enzymes can be regulated?

Accepted Answer

Changing the DNA sequence of the enzyme after it is made

Question 16

A mutation causes an enzyme to lose its optimal pH. What is the most likely consequence?

Accepted Answer

The enzyme's activity will decrease at its original optimal pH.

Question 17

Which of the following statements about metabolic pathways is correct?

Accepted Answer

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

Question 18

Which of the following is a correct description of the role of NAD+ in cellular metabolism?

Accepted Answer

NAD+ accepts electrons and a proton to become NADH, acting as an electron carrier.

Question 19

A researcher observes that a reaction has $$\Delta H  0. $$What can be concluded about $$\Delta G at $$any temperature?

Accepted Answer

$$\Delta G$$ will always be negative.

Question 20

Which of the following best describes the process of retro-evolution in metabolic pathway evolution?

Accepted Answer

Enzymes evolve to produce more of a substrate as it becomes depleted, leading to the formation of new steps in a pathway.

Chapter 8: Energy and Enzymes—An Introduction to Metabolism

Guida di studio - Domande di pratica

Study guide - Flashcard