Question 1

Which of the following best describes the difference between anabolic and catabolic pathways, as illustrated in the metabolic pathways diagram?

Accepted Answer

Anabolic pathways assemble small molecules into large ones, requiring energy, while catabolic pathways break down large molecules into smaller ones, releasing energy.

Question 2

In the context of cellular respiration, why is the stepwise oxidation of glucose in cells more advantageous than direct burning, as shown in the energy diagram?

Accepted Answer

Stepwise oxidation allows energy to be released gradually and captured in activated carrier molecules such as ATP and NADH.

Question 3

Which of the following statements about ATP is correct based on its role in metabolism?

Accepted Answer

ATP hydrolysis is highly exergonic due to charge repulsion, resonance stabilization, and increased entropy of the products.

Question 4

Which of the following best explains why ATP is considered the 'energy currency' of the cell?

Accepted Answer

ATP can transfer phosphate groups to compounds with lower free energy of hydrolysis, driving endergonic reactions.

Question 5

Which of the following is a direct result of the resonance stabilization of inorganic phosphate (Pi) after ATP hydrolysis?

Accepted Answer

The electrons in Pi are delocalized, making Pi more stable and lowering the free energy of the system.

Question 6

In the context of chemotrophic energy metabolism, what is the primary role of NAD+?

Accepted Answer

NAD+ serves as an electron carrier, accepting electrons and protons during oxidation reactions to form NADH.

Question 7

Which of the following best describes the fate of pyruvate in human muscle cells under anaerobic conditions?

Accepted Answer

Pyruvate is converted to lactate to regenerate NAD+ for glycolysis.

Question 8

Why do cancer cells often rely on glycolysis for ATP production even in the presence of oxygen, as shown in the Warburg effect diagram?

Accepted Answer

Glycolysis is much faster than oxidative phosphorylation, allowing rapid ATP production to support uncontrolled cell growth.

Question 9

Which of the following statements about fermentation is correct?

Accepted Answer

Fermentation allows glycolysis to continue by regenerating NAD+ in the absence of oxygen.

Question 10

A cell is exposed to a toxin that inhibits the electron transport chain. Which of the following outcomes is most likely?

Accepted Answer

The cell will increase its rate of glycolysis and fermentation to compensate for the loss of ATP production.

Question 11

Which of the following best explains why the hydrolysis of ATP is used to drive endergonic reactions in cells?

Accepted Answer

ATP hydrolysis is highly exergonic, providing the free energy needed to drive unfavorable reactions.

Question 12

Which of the following is a consequence of the increased entropy after ATP hydrolysis?

Accepted Answer

The reaction becomes more exergonic due to the increased disorder and solubility of the products.

Question 13

Which of the following best describes the role of oxygen in aerobic respiration?

Accepted Answer

Oxygen serves as the terminal electron acceptor, allowing for efficient ATP production.

Question 14

Which of the following is a real-life application of the ATP assay, as shown in the provided images?

Accepted Answer

Quantifying cellular energy levels by detecting ATP concentration, such as in bioluminescent reactions.

Question 15

Which of the following statements about the ATP/ADP system is correct?

Accepted Answer

ADP can be phosphorylated to ATP by compounds with higher free energy of hydrolysis, such as phosphoenolpyruvate (PEP).

Question 16

Which of the following best explains why obligate anaerobes cannot survive in the presence of oxygen?

Accepted Answer

Oxygen is toxic to their cellular machinery, and they lack the enzymes to detoxify reactive oxygen species.

Question 17

Which of the following is a correct statement about the energy yield of aerobic versus anaerobic respiration?

Accepted Answer

Anaerobic respiration yields about 2 ATP per glucose, while aerobic respiration can yield up to 38 ATP per glucose.

Question 18

Which of the following best describes the role of high-energy molecules such as GTP and creatine phosphate in cellular metabolism?

Accepted Answer

They store chemical energy that can be transferred to ADP to regenerate ATP.

Question 19

A mutation causes a cell to be unable to regenerate NAD+ from NADH. Which metabolic process would be most directly affected?

Accepted Answer

Glycolysis would slow or stop due to the lack of NAD+ as an electron acceptor.

Chemotrophic Energy Metabolism: Glycolysis and Fermentation – Study Notes

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