Question 1

Which of the following best describes the role of ATP in cellular metabolism?

Accepted Answer

ATP acts as a universal energy coupler, transferring phosphate groups to and from molecules to drive endergonic reactions.

Question 2

Which equation correctly represents the hydrolysis of ATP, and what is the associated free energy change?

Accepted Answer

$$\mathrm{$$ATP^{4-}$$ + H_2O \rightarrow $$ADP^{3-}$$ + P_i$$^{2-}$$ + H^+}$$; $$\Delta G^\circ' = -7.3$$ kcal/mol

Question 3

During glycolysis, how many net ATP molecules are produced per molecule of glucose?

Accepted Answer

2

Question 4

Which of the following statements about fermentation is correct?

Accepted Answer

Fermentation occurs in the absence of oxygen and regenerates NAD+ by oxidizing NADH, allowing glycolysis to continue.

Question 5

Which enzyme is responsible for the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate in glycolysis, and how is it regulated?

Accepted Answer

Phosphofructokinase-1 (PFK-1), which is allosterically activated by AMP and fructose-2,6-bisphosphate.

Question 6

Which of the following best explains why glycolysis can proceed under anaerobic conditions?

Accepted Answer

NAD+ is regenerated by fermentation, allowing glycolysis to continue producing ATP.

Question 7

Which metabolic pathway is primarily responsible for synthesizing glucose from pyruvate, and what is a key difference from glycolysis?

Accepted Answer

Gluconeogenesis; it bypasses the three most exergonic reactions of glycolysis using energy input from ATP and GTP.

Question 8

A patient with a genetic deficiency in triose phosphate isomerase would most likely experience which of the following?

Accepted Answer

Reduced efficiency of glycolysis due to impaired interconversion of glyceraldehyde-3-phosphate and dihydroxyacetone phosphate.

Question 9

Which of the following is a correct classification of metabolic pathways?

Accepted Answer

Anabolic pathways build complex molecules from simpler ones and require energy input.

Question 10

Which molecule acts as an important allosteric regulator of both glycolysis and gluconeogenesis, and how is its concentration controlled?

Accepted Answer

Fructose-2,6-bisphosphate (F2,6BP); its concentration is controlled by the bifunctional enzyme PFK-2/F2,6BPase.

Question 11

Which of the following best describes the fate of pyruvate under aerobic conditions in most cells?

Accepted Answer

Pyruvate is converted to acetyl CoA, which enters the citric acid cycle for further oxidation.

Question 12

Which of the following sugars can enter glycolysis after conversion to an intermediate, and what is the intermediate?

Accepted Answer

Galactose; it is converted to glucose-6-phosphate.

Question 13

Which of the following is a plausible consequence of increased cAMP levels in a liver cell?

Accepted Answer

Activation of protein kinase, leading to phosphorylation of PFK-2/F2,6BPase and decreased glycolysis.

Question 14

Which of the following best explains why most of the energy from glucose remains in fermentation end-products?

Accepted Answer

Fermentation does not fully oxidize glucose; only partial oxidation occurs, leaving most energy in lactate or ethanol.

Question 15

Which of the following is a correct statement about the regulation of glycolysis and gluconeogenesis?

Accepted Answer

They are regulated by modifying the activity of enzymes unique to each pathway, often through allosteric effectors such as ATP, AMP, and citrate.

Question 16

A muscle cell is rapidly contracting and has high levels of AMP. Which effect would this have on glycolysis?

Accepted Answer

AMP would activate phosphofructokinase-1 (PFK-1), increasing the rate of glycolysis.

Question 17

Which of the following is a multi-step process that integrates both glycolysis and fermentation in yeast cells?

Accepted Answer

Glucose is converted to pyruvate via glycolysis, then pyruvate is converted to ethanol and CO$$_2$$ via fermentation.

Question 18

Which of the following best describes the role of phosphoenolpyruvate (PEP) in glycolysis?

Accepted Answer

PEP donates a phosphate group to ADP, forming ATP and pyruvate in the final step of glycolysis.

Question 19

Which of the following is a real-world example of glycolytic regulation relevant to cancer biology?

Accepted Answer

Several glycolytic enzymes play regulatory roles in cancer cell migration and gene expression.

Chemotropic Energy Metabolism: Glycolysis and Fermentation – Study Notes

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