Question 1

Which statement best describes the difference between anabolic and catabolic pathways in cellular 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

According to the first law of thermodynamics, which of the following is true regarding energy in biological systems?

Accepted Answer

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

Question 3

A scientist calculates the change in free energy ($\Delta G$) for a reaction using the equation $\Delta G = \Delta H - T\Delta S$. If $\Delta H = -100$ kJ/mol, $T = 300$ K, and $\Delta S = 0.2$ kJ/(mol·K), what is $\Delta G$?

Accepted Answer

$\Delta G = -160$ kJ/mol

Question 4

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

Accepted Answer

They continuously exchange energy and matter with their surroundings, preventing equilibrium and allowing ongoing metabolic work.

Question 5

Which of the following is NOT a form of energy relevant to biological systems?

Accepted Answer

Gravitational energy

Question 6

During ATP hydrolysis, which of the following occurs?

Accepted Answer

ATP is converted to ADP and a phosphate group, releasing energy that can be used to drive endergonic reactions.

Question 7

Which statement about enzymes is correct?

Accepted Answer

Enzymes lower the activation energy ($E_a$) of a reaction, speeding up the rate without changing the overall free energy change ($\Delta G$).

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 increase the effectiveness of the enzyme despite the presence of the inhibitor?

Accepted Answer

Increasing the concentration of the substrate.

Question 9

Which of the following best describes feedback inhibition in metabolic pathways?

Accepted Answer

The end product of a pathway inhibits an enzyme involved earlier in the pathway, preventing overproduction.

Question 10

Which scenario illustrates the second law of thermodynamics in a biological context?

Accepted Answer

A plant uses light energy to make organic molecules, releasing heat and increasing the entropy of its surroundings.

Question 11

Which of the following is true about the relationship between free energy ($G$), stability, and equilibrium in biological systems?

Accepted Answer

Systems with lower free energy ($G$) are more stable; equilibrium represents maximum stability.

Question 12

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

Accepted Answer

Hydrolysis of ATP to ADP and inorganic phosphate.

Question 13

A metabolic pathway in a cell consists of several steps, each catalyzed by a different enzyme. What is the advantage of this organization?

Accepted Answer

It enables precise regulation and control of each step, increasing efficiency and adaptability.

Question 14

Which of the following statements about enzyme regulation is correct?

Accepted Answer

Cooperativity occurs when substrate binding to one active site increases the activity at other active sites.

Question 15

Which factor is most likely to cause an enzyme to denature and lose its catalytic activity?

Accepted Answer

A significant increase in temperature above the enzyme's optimal range.

Question 16

Which of the following is a correct statement about the role of cofactors in enzyme activity?

Accepted Answer

Cofactors can be inorganic ions or organic molecules (coenzymes) that assist enzyme function.

Question 17

A cell is observed to have a high concentration of ADP and inorganic phosphate. What does this suggest about the cell's energy status?

Accepted Answer

The cell is likely in need of energy and will increase catabolic reactions to regenerate ATP.

Question 18

Which of the following best describes the induced fit model of enzyme-substrate interaction?

Accepted Answer

The enzyme changes shape slightly to better fit the substrate upon binding, enhancing catalysis.

Question 19

Which of the following would most likely decrease the rate of an enzyme-catalyzed reaction in a human cell?

Accepted Answer

Lowering the temperature below the enzyme's optimal range.

Chapter 8: An Introduction to Metabolism – Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards