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

Which equation correctly represents the relationship between free energy, enthalpy, entropy, and temperature in a biological system?

Accepted Answer

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

Question 3

A reaction has $$\Delta G = -15$$ kcal/mol. What does this indicate about the reaction?

Accepted Answer

The reaction is spontaneous and can perform work.

Question 4

Which of the following is an example of energy coupling in cells?

Accepted Answer

The hydrolysis of ATP to ADP and $$P_i$$ powers the active transport of ions across a membrane.

Question 5

Why is ATP considered a high-energy molecule?

Accepted Answer

Because the repulsion between the negatively charged phosphate groups creates high potential energy.

Question 6

Which statement about enzymes is FALSE?

Accepted Answer

Enzymes change the overall $$\Delta G of a $$reaction.

Question 7

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 8

Which of the following best explains why cells never reach metabolic equilibrium?

Accepted Answer

Cells constantly allow materials to flow in and out, preventing equilibrium.

Question 9

Which of the following is a real-life example of the second law of thermodynamics in biological systems?

Accepted Answer

A bear eating fish and converting chemical energy to kinetic energy and heat.

Question 10

Which of the following statements about feedback inhibition is correct?

Accepted Answer

Feedback inhibition prevents the cell from wasting resources by shutting down a pathway when the end product is abundant.

Question 11

Which of the following would most likely increase the rate of an enzyme-catalyzed reaction that is currently saturated with substrate?

Accepted Answer

Adding more enzyme to the reaction mixture.

Question 12

Which of the following best describes the role of cofactors in enzyme activity?

Accepted Answer

Cofactors are nonprotein helpers that are required for some enzymes to function properly.

Question 13

A cell is performing active transport of sodium ions across its membrane. Which molecule is directly providing the energy for this process?

Accepted Answer

ATP

Question 14

Which of the following is true about the effect of temperature on enzyme activity?

Accepted Answer

Each enzyme has an optimal temperature, above which the enzyme denatures and activity decreases.

Question 15

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

Accepted Answer

Cellular respiration in animals

Question 16

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

Accepted Answer

ATP is regenerated from ADP and $$P_i$$ using energy from catabolic (exergonic) reactions.

Question 17

Which of the following best explains why adding heat is not a useful way to speed up reactions in cells?

Accepted Answer

Heat can denature proteins and speed up all reactions, not just those needed by the cell.

Question 18

Which of the following is a correct statement about noncompetitive enzyme inhibitors?

Accepted Answer

They bind to a site other than the active site, causing a conformational change that reduces enzyme activity.

Question 19

Which of the following is an example of allosteric regulation?

Accepted Answer

A molecule binds to a regulatory site on an enzyme, stabilizing its active form.

Question 20

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.

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

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