Question 1

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

Accepted Answer

Catabolic reactions break down complex molecules to release energy, while anabolic reactions use energy to synthesize complex molecules from simpler ones.

Question 2

Which of the following is NOT considered a central pathway of energy metabolism in aerobic organisms?

Accepted Answer

Fatty acid synthesis

Question 3

Which statement about ATP is FALSE?

Accepted Answer

ATP hydrolysis is rapid and spontaneous under physiological conditions.

Question 4

Which of the following best explains why glycolysis and gluconeogenesis do not occur simultaneously in the same cell compartment?

Accepted Answer

Reciprocal regulation ensures that only one pathway is active at a time, preventing a futile cycle.

Question 5

Which of the following is a major role of NAD+ in metabolism?

Accepted Answer

It serves as a major oxidant, accepting electrons during catabolic reactions.

Question 6

A reaction has a standard free energy change $$\Delta G^\circ = +16.3\ \mathrm{kJ/mol}. $$What is the effect of coupling this reaction to ATP hydrolysis ($$\Delta G^\circ = -30.5\ \mathrm{kJ/mol}) in a $$metabolic pathway?

Accepted Answer

The overall reaction becomes exergonic and can proceed spontaneously.

Question 7

Which of the following best describes the function of a flux control coefficient (FCC) in metabolic control analysis?

Accepted Answer

It indicates the regulatory significance of an enzyme within a pathway.

Question 8

Which of the following is a correct statement about the regulation of energy metabolism?

Accepted Answer

The adenylyl energy charge, defined as $$\frac{[ATP]}{[ATP] + [ADP] + [AMP]}$$, is a key regulatory parameter.

Question 9

Which of the following is NOT a common type of chemical transformation found in living systems?

Accepted Answer

Electrophilic elimination

Question 10

Why is ATP, rather than other nucleoside triphosphates, the primary energy currency in cells?

Accepted Answer

ATP is the most abundant NTP in cells, making it the most available phosphate donor.

Question 11

A patient is found to have a mutation that reduces the activity of a single enzyme in a metabolic pathway. According to metabolic control analysis, what is the most likely effect on the overall flux through the pathway?

Accepted Answer

The flux will decrease, but the magnitude depends on the enzyme's flux control coefficient (FCC).

Question 12

Which of the following statements about NAD+ and NADP+ is TRUE?

Accepted Answer

NADP+ is primarily used as an electron donor in biosynthetic reactions.

Question 13

Which of the following is an example of substrate-level phosphorylation?

Accepted Answer

ATP synthesis from ADP and inorganic phosphate using energy released from the breakdown of phosphoenolpyruvate.

Question 14

Which of the following is a reason why metabolite concentrations are kept low in cells?

Accepted Answer

To avoid exceeding the solvent capacity of the cell.

Question 15

Which of the following best describes the role of allosteric effectors in the regulation of metabolic pathways?

Accepted Answer

They allow for rapid, reversible regulation of enzyme activity in response to cellular signals.

Question 16

Which of the following is an example of functional compartmentation in metabolism?

Accepted Answer

The grouping of sequentially acting enzymes to allow high local concentrations of intermediates.

Question 17

Which of the following statements about the oxidation of glucose in aerobic organisms is correct?

Accepted Answer

The overall reaction is $$C_6H_{12}O_6$ + 6O_2 \rightarrow 6CO_2 + 6H_2O$$ with $$\Delta G = -2870\ \mathrm{kJ/mol}.$$

Question 18

Which of the following is NOT a mechanism of metabolic control?

Accepted Answer

Direct hydrolysis of all metabolic intermediates

Question 19

Which of the following best describes the role of cyclic AMP (cAMP) in metabolic regulation?

Accepted Answer

It is a second messenger that transduces signals from hormones to intracellular targets.

Chemical Logic of Metabolism: An Overview of Metabolic Pathways and Regulation

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