Question 1

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

Accepted Answer

Anabolic pathways synthesize cellular components and require energy, while catabolic pathways break down cellular components and release energy.

Question 2

Which molecule is considered the primary energy currency of the cell, and what is the main reason its hydrolysis is highly exergonic?

Accepted Answer

ATP; due to charge repulsion between adjacent phosphate groups.

Question 3

During glycolysis, which enzyme catalyzes the phosphorylation of glucose, and what is the significance of this reaction?

Accepted Answer

Hexokinase; it traps glucose inside the cell.

Question 4

What is the net ATP yield from glycolysis per molecule of glucose under anaerobic conditions?

Accepted Answer

$$2$$

Question 5

Which coenzyme is most commonly involved in energy metabolism as an electron acceptor, and what is the reaction it undergoes during glycolysis?

Accepted Answer

NAD^+; $$\mathrm{NAD}^+ + 2[H] \rightarrow \mathrm{NADH} + \mathrm{H}^+$$

Question 6

In the absence of oxygen, what is the fate of pyruvate in human muscle cells, and why is this process important?

Accepted Answer

It is converted to lactate; this regenerates $$\mathrm{NAD}^+$$ for glycolysis to continue.

Question 7

Which enzyme deficiency leads to hemolytic anemia due to impaired glycolysis in red blood cells, and what is the underlying reason?

Accepted Answer

Pyruvate kinase deficiency; red blood cells cannot generate sufficient ATP.

Question 8

The Warburg effect describes a phenomenon in cancer cells where energy is produced primarily by which process, even in the presence of oxygen?

Accepted Answer

Glycolysis followed by lactic acid fermentation in the cytosol

Question 9

Which step in glycolysis is considered the 'commitment' step, and what regulates the enzyme responsible for this reaction?

Accepted Answer

Phosphorylation of fructose 6-phosphate to fructose 1,6-bisphosphate by phosphofructokinase; regulated by ATP, ADP, and AMP levels.

Question 10

Which of the following best explains why biological oxidation reactions are highly exergonic?

Accepted Answer

They involve the removal of electrons and protons from oxidizable compounds, releasing energy.

Question 11

What is the overall chemical equation for the complete aerobic oxidation of glucose?

Accepted Answer

$$\mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 6\mathrm{O}_2 \rightarrow 6\mathrm{CO}_2 + 6\mathrm{H}_2\mathrm{O}$$

Question 12

Which glycolytic enzyme catalyzes the formation of ATP via substrate-level phosphorylation, and what is the substrate for this reaction?

Accepted Answer

Phosphoglycerate kinase; 1,3-bisphosphoglycerate

Question 13

Which of the following statements about NAD^+ is correct?

Accepted Answer

It serves as an electron acceptor and is reduced to NADH during glycolysis.

Question 14

Why is the hydrolysis of ATP to ADP and $$\mathrm{P}_i$$ considered highly exergonic?

Accepted Answer

Because of charge repulsion, resonance stabilization of products, and increased entropy.

Question 15

Which metabolic pathway is responsible for the breakdown of glucose to pyruvate, and what is the location of this process in the cell?

Accepted Answer

Glycolysis; cytoplasm

Question 16

A patient presents with muscle fatigue during intense exercise. Laboratory tests show elevated lactate levels. Which metabolic process is most likely responsible for this finding?

Accepted Answer

Anaerobic glycolysis followed by lactic acid fermentation

Question 17

Which of the following is a function of kinases in glycolysis?

Accepted Answer

Transfer phosphate groups to or from ATP

Question 18

Which glycolytic intermediate contains a high-energy acyl phosphate bond, and what is its significance?

Accepted Answer

1,3-bisphosphoglycerate; it drives substrate-level phosphorylation of ADP to ATP

Question 19

Which enzyme catalyzes the conversion of 2-phosphoglycerate to phosphoenolpyruvate (PEP), and what is the importance of PEP in glycolysis?

Accepted Answer

Enolase; PEP contains a high-energy phosphate linkage used to generate ATP

Cellular Energy Metabolism: Glycolysis, Fermentation, and ATP in Cell Biology

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