Question 1

Which of the following best describes the difference between anabolic and catabolic pathways in 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 scientist measures the change in free energy ($$\Delta G) $$for a chemical reaction in a cell and finds $$\Delta G = -15 kJ/$$mol. What does this indicate about the reaction?

Accepted Answer

The reaction is spontaneous and can perform work as it proceeds toward equilibrium.

Question 3

Which equation correctly relates the change in free energy ($$\Delta G) to $$enthalpy ($$\Delta H$$), entropy ($$\Delta S$$), and temperature ($$T$$)?

Accepted Answer

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

Question 4

Which of the following is an example of energy transformation in a biological system that illustrates the first law of thermodynamics?

Accepted Answer

A plant using sunlight to synthesize glucose from carbon dioxide and water.

Question 5

Why is ATP hydrolysis considered to be highly exergonic?

Accepted Answer

Because the repulsion between negatively charged phosphate groups in ATP is relieved when a phosphate is removed, releasing free energy.

Question 6

A cell couples the hydrolysis of ATP ($$\Delta G = -30.5 kJ/$$mol) to an endergonic reaction with $$\Delta G = +20 kJ/$$mol. What is the overall $$\Delta G$$ for the coupled reaction, and is it spontaneous?

Accepted Answer

$$\Delta G = -10.5 kJ/$$mol; the reaction is spontaneous.

Question 7

Which of the following statements about enzymes is TRUE?

Accepted Answer

Enzymes speed up reactions by lowering the activation energy ($$E_a) $$without being consumed in the process.

Question 8

A patient is given a drug that acts as a competitive inhibitor for a key metabolic enzyme. Which of the following would most likely reduce the drug's inhibitory effect?

Accepted Answer

Increasing the concentration of the enzyme's substrate.

Question 9

Which of the following best explains why living cells are considered open systems?

Accepted Answer

They exchange both energy and matter with their surroundings, preventing equilibrium and allowing continuous work.

Question 10

A metabolic pathway is regulated by feedback inhibition. Which of the following best describes this process?

Accepted Answer

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

Question 11

Which of the following is a correct statement about the second law of thermodynamics as it applies to living organisms?

Accepted Answer

Every energy transfer or transformation in living organisms increases the entropy of the universe.

Question 12

Which of the following scenarios best illustrates the concept of energy coupling in cells?

Accepted Answer

A cell uses the energy released from ATP hydrolysis to drive the active transport of sodium ions against their concentration gradient.

Question 13

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

Accepted Answer

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

Question 14

A researcher finds that an enzyme works best at pH 2 and loses activity at higher pH values. Where is this enzyme most likely to be found in the human body?

Accepted Answer

In the stomach.

Question 15

Which of the following best describes noncompetitive inhibition of an enzyme?

Accepted Answer

The inhibitor binds to a site other than the active site, causing a conformational change that reduces enzyme activity.

Question 16

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

Accepted Answer

A termite digesting plant material and releasing heat to the environment.

Question 17

Which of the following statements about the regeneration of ATP in cells is correct?

Accepted Answer

ATP is regenerated from ADP and inorganic phosphate using energy from catabolic (exergonic) reactions.

Question 18

A mutation causes an enzyme to lose its ability to bind its cofactor. What is the most likely consequence?

Accepted Answer

The enzyme will lose catalytic activity because many enzymes require cofactors to function.

Question 19

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

Accepted Answer

The active site of an enzyme has a unique shape that fits only specific substrate molecules.

Chapter 8: An Introduction to Metabolism – Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards