Question 1

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

Accepted Answer

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

Question 2

A cell is synthesizing a protein from amino acids. Which type of metabolic pathway is primarily involved, and what is the energy requirement?

Accepted Answer

Anabolic pathway; energy is consumed

Question 3

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

Accepted Answer

The total amount of energy in a closed system remains constant; energy can be transferred or transformed but not created or destroyed.

Question 4

A diver climbs up a platform, converting the kinetic energy of muscle movement into potential energy. Which law of thermodynamics is illustrated when some of this energy is lost as heat?

Accepted Answer

Second law of thermodynamics

Question 5

Which of the following equations correctly represents the hydrolysis of ATP?

Accepted Answer

$ \mathrm{ATP} + \mathrm{H}_2\mathrm{O} \rightarrow \mathrm{ADP} + \mathrm{P}_i $

Question 6

Which of the following best explains why ATP is considered the main energy currency in cells?

Accepted Answer

ATP hydrolysis releases a large amount of free energy that can be coupled to endergonic reactions.

Question 7

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

Accepted Answer

Exergonic reactions are spontaneous and release free energy; endergonic reactions are non-spontaneous and require an input of free energy.

Question 8

A scientist is studying a metabolic pathway in which the product of the final step inhibits the enzyme that catalyzes the first step. What is this regulatory mechanism called?

Accepted Answer

Feedback inhibition

Question 9

Which of the following best describes the role of enzymes in biological reactions?

Accepted Answer

Enzymes lower the activation energy ($ E_A $) required for a reaction to proceed.

Question 10

Which of the following is an example of a redox reaction in cellular metabolism?

Accepted Answer

$ \mathrm{XH}_2 + \mathrm{NAD}^+ \rightarrow \mathrm{X} + \mathrm{NADH} + \mathrm{H}^+ $

Question 11

A patient is given a drug that acts as a noncompetitive inhibitor of an essential enzyme. What is the most likely effect of this drug on the enzyme's activity?

Accepted Answer

It will bind to a site other than the active site, causing a conformational change that reduces enzyme activity regardless of substrate concentration.

Question 12

Which of the following statements about enzyme specificity is correct?

Accepted Answer

Enzymes are generally highly specific due to the unique shape and chemical environment of their active sites.

Question 13

Which of the following best explains why metabolism in living organisms is never at equilibrium?

Accepted Answer

Cells are open systems, constantly exchanging energy and matter with their environment, preventing equilibrium.

Question 14

A researcher observes that an enzyme-catalyzed reaction proceeds much faster at pH 7 than at pH 3 or pH 11. What is the most likely explanation?

Accepted Answer

The enzyme has an optimal pH near 7, and extremes of pH denature the enzyme or alter its active site.

Question 15

Which of the following is a correct statement about the ATP cycle in a working muscle cell?

Accepted Answer

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

Question 16

Which of the following is an example of a coenzyme required for enzyme function?

Accepted Answer

NAD+

Question 17

A metabolic pathway is regulated by feedback inhibition. What would happen if the final product of the pathway is removed from the cell?

Accepted Answer

The pathway would speed up because the inhibition is relieved and the first enzyme is active again.

Question 18

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

Accepted Answer

Enzyme activity is highest at an optimal temperature, usually close to human body temperature, and decreases at temperatures above or below this optimum.

Question 19

Which of the following statements about redox reactions in metabolism is correct?

Accepted Answer

Oxidation is the loss of electrons, and reduction is the gain of electrons; both occur simultaneously.

Chapter 8: Energy and Metabolism – Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards