Question 1

Which of the following statements 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 molecules and release energy.

Question 2

Which of the following is the correct balanced equation for the complete aerobic oxidation of glucose?

Accepted Answer

$$C_6H_{12}O_6$ + 6O_2 \rightarrow 6CO_2 + 6H_2O$$

Question 3

During glycolysis, which step is responsible for the direct generation of NADH?

Accepted Answer

Oxidation of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate

Question 4

Which of the following best explains why ATP hydrolysis is highly exergonic?

Accepted Answer

ATP hydrolysis results in increased entropy and resonance stabilization of the products.

Question 5

A patient is injected with fluorodeoxyglucose (FDG) for a PET scan. Which tissue would show the highest FDG accumulation and why?

Accepted Answer

Tumor tissue, because it has high hexokinase activity and rapidly consumes glucose.

Question 6

Which enzyme is responsible for the irreversible phosphorylation of glucose in the first step of glycolysis?

Accepted Answer

Hexokinase

Question 7

In the absence of oxygen, what is the fate of pyruvate in human muscle cells?

Accepted Answer

It is reduced to lactate by lactate dehydrogenase.

Question 8

Which of the following statements about NAD+/NADH is correct?

Accepted Answer

NAD+ acts as an electron acceptor during glycolysis, forming NADH.

Question 9

Which of the following is a key regulatory enzyme unique to gluconeogenesis?

Accepted Answer

Fructose-1,6-bisphosphatase

Question 10

Cancer cells often display aerobic glycolysis. What is the primary reason for this metabolic adaptation?

Accepted Answer

To produce carbon skeletons for biosynthesis needed for rapid proliferation.

Question 11

Which of the following equations represents the net reaction for alcoholic fermentation?

Accepted Answer

$$C_6H_{12}O_6$ + 2ADP + 2P_i + 2H^+ \rightarrow 2C_2H_5OH + 2CO_2 + 2ATP$$

Question 12

Which of the following best describes the role of phosphofructokinase-1 (PFK-1) in glycolysis?

Accepted Answer

It is the main regulatory enzyme, catalyzing the phosphorylation of fructose-6-phosphate to fructose-1,6-bisphosphate.

Question 13

Which of the following statements about the energetics of glycolysis is correct?

Accepted Answer

Glycolysis produces a net gain of 2 ATP per glucose molecule.

Question 14

Which of the following is true regarding the regulation of glycolysis and gluconeogenesis?

Accepted Answer

Glycolysis is activated by AMP, while gluconeogenesis is activated by acetyl-CoA.

Question 15

Which of the following metabolic classifications describes an organism that uses light as an energy source and CO$$_2 as a $$carbon source?

Accepted Answer

Photoautotroph

Question 16

Which of the following is a reason why biosynthetic anabolic pathways cannot be simple reversals of catabolic pathways?

Accepted Answer

Anabolic pathways require different enzymes to bypass highly exergonic steps.

Question 17

Which of the following is the main electron carrier in catabolic reactions?

Accepted Answer

NAD+/NADH

Question 18

During strenuous exercise, muscle cells produce lactate. What happens to this lactate after it is transported to the liver?

Accepted Answer

It is converted back to glucose via gluconeogenesis.

Question 19

Which of the following best explains why fermentation yields less ATP per glucose than aerobic respiration?

Accepted Answer

Fermentation does not fully oxidize glucose, leaving most energy in lactate or ethanol.

Cellular Metabolism and Energetics: Key Concepts and Pathways

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