Question 1

Which statement best describes the first law of thermodynamics as it applies to biological systems?

Accepted Answer

Energy can be transferred and transformed, but it cannot be created or destroyed.

Question 2

A bear eats a fish and uses the energy to run. According to the second law of thermodynamics, what happens to the energy during this process?

Accepted Answer

Some energy is lost as heat, increasing the entropy of the surroundings.

Question 3

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

Accepted Answer

$$\Delta G = G_{final} - G_{initial}$$

Question 4

Which of the following is true for a spontaneous reaction in a biological system?

Accepted Answer

$$\Delta G is $$negative and the reaction increases the stability of the system.

Question 5

Which scenario best illustrates energy coupling in a cell?

Accepted Answer

ATP hydrolysis releases energy that is used to drive an endergonic reaction.

Question 6

What is the primary function of enzymes in metabolic pathways?

Accepted Answer

Enzymes lower the activation energy barrier, speeding up reactions.

Question 7

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

Accepted Answer

Enzyme activity increases with temperature up to an optimal point, then decreases as the enzyme denatures.

Question 8

A metabolic pathway is regulated by feedback inhibition. Which statement best describes this process?

Accepted Answer

The end product of the pathway inhibits an enzyme early in the pathway, preventing overproduction.

Question 9

Which of the following is an example of an exergonic reaction in metabolism?

Accepted Answer

Cellular respiration converting glucose and oxygen to carbon dioxide and water.

Question 10

What is the role of cofactors in enzyme activity?

Accepted Answer

Cofactors are nonprotein molecules that help enzymes carry out difficult processes.

Question 11

Which of the following statements about ATP hydrolysis is correct?

Accepted Answer

ATP hydrolysis releases energy due to the chemical change to a state of lower free energy.

Question 12

Which type of enzyme inhibitor binds to the active site and prevents substrate binding?

Accepted Answer

Competitive inhibitor

Question 13

What is the effect of enzyme saturation on the rate of catalysis?

Accepted Answer

The rate of catalysis cannot increase unless more enzyme is added.

Question 14

Which of the following is a correct description of an anabolic pathway?

Accepted Answer

Anabolic pathways consume energy to build complex molecules from simpler ones.

Question 15

Which process is an example of energy transformation in biological systems?

Accepted Answer

Light energy from the sun is transformed into chemical energy in plants.

Question 16

Which equation represents the net free-energy change for the coupled reaction of glutamic acid conversion to glutamine, given $$\Delta G_{Glu} = +3.4$$ kcal/mol and $$\Delta G_{ATP} = -7.3$$ kcal/mol?

Accepted Answer

$$\Delta G_{net} = +3.4 + (-7.3) = -3.9$$ kcal/mol

Question 17

Which of the following best describes the role of allosteric regulation in enzyme activity?

Accepted Answer

Allosteric regulation can either inhibit or stimulate enzyme activity by binding to a site other than the active site.

Question 18

Why does the evolution of complex organisms not violate the second law of thermodynamics?

Accepted Answer

Entropy may decrease in a system, but the total entropy of the universe increases.

Question 19

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

Accepted Answer

Increasing the temperature of the reaction

Chapter 6: An Introduction to Metabolism – Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards