Q: Which of the following equations correctly represents the net ATP yield from glycolysis alone per molecule of glucose?

$$2 \text{ ADP} + 2 \text{ P}_i + \text{Glucose} \rightarrow 2 \text{ ATP} + 2 \text{ Pyruvate}$$

Q: Which of the following equations represents the regeneration of NAD$$^+$$ during lactic acid fermentation?

$$\text{Pyruvate} + \text{NADH} \rightarrow \text{Lactate} + \text{NAD}^+$$

Question 1

Which of the following best explains why different tissues in the body use different metabolic fuels under various physiological conditions?

Accepted Answer

Tissue-specific function creates unique energetic and biosynthetic demands, leading to metabolic flexibility.

Question 2

During prolonged fasting, which fuel source becomes increasingly important for the brain, and why?

Accepted Answer

Ketone bodies, because they are synthesized by the liver and can be used by the brain when glucose is scarce.

Question 3

Which of the following equations correctly represents the net ATP yield from glycolysis alone per molecule of glucose?

Accepted Answer

$$2 	ext{ ADP} + 2 	ext{ P}_i + 	ext{Glucose} ightarrow 2 	ext{ ATP} + 2 	ext{ Pyruvate}$$

Question 4

Why does lactic acid fermentation allow glycolysis to continue in the absence of oxygen?

Accepted Answer

It regenerates NAD$$^+$$ from NADH, allowing glycolysis to continue producing ATP.

Question 5

Which of the following best describes the main metabolic fuel used by the heart under normal, fasted conditions in a healthy individual?

Accepted Answer

Fatty acids

Question 6

A sprinter is running at maximum effort and their muscles are rapidly consuming ATP. Which metabolic pathway is most active in their muscle cells under these conditions?

Accepted Answer

Lactic acid fermentation

Question 7

Which of the following statements about fermentation is correct?

Accepted Answer

Fermentation allows glycolysis to continue by regenerating NAD$$^+$$, but does not produce additional ATP beyond glycolysis.

Question 8

Which of the following best explains why lactate can be produced in muscle even when oxygen is present?

Accepted Answer

High ATP demand can exceed the rate of oxygen delivery, causing glycolysis to outpace oxidative phosphorylation.

Question 9

Which of the following is a correct summary of the fate of pyruvate under aerobic and anaerobic conditions?

Accepted Answer

Aerobic: Pyruvate is converted to acetyl-CoA and enters the citric acid cycle; Anaerobic: Pyruvate is converted to lactate or ethanol.

Question 10

A patient with a genetic defect that impairs the electron transport chain will most likely show which of the following metabolic consequences?

Accepted Answer

Increased reliance on glycolysis and fermentation for ATP production

Question 11

Which of the following equations represents the regeneration of NAD$$^+$$ during lactic acid fermentation?

Accepted Answer

$$	ext{Pyruvate} + 	ext{NADH} ightarrow 	ext{Lactate} + 	ext{NAD}^+$$

Question 12

Which of the following best describes the liver's role in metabolic coordination during fasting?

Accepted Answer

The liver synthesizes glucose and ketone bodies, releasing them to supply other tissues.

Question 13

Which of the following is NOT a constraint on organismal growth according to the study materials?

Accepted Answer

ATP as the only limiting factor

Question 14

In Hammond’s pig studies, what was the main finding regarding tissue composition and feeding schedules?

Accepted Answer

Pigs with different feeding schedules could reach similar final body weights but have different proportions of bone, muscle, and fat.

Question 15

Which of the following best explains why the heart is considered a metabolic specialist in sustained contraction?

Accepted Answer

It contains abundant mitochondria and can oxidize fatty acids, glucose, lactate, and ketones depending on supply and physiological state.

Question 16

Which of the following best describes metabolic flexibility?

Accepted Answer

The ability of tissues to switch between different fuel sources depending on physiological state and nutrient availability.

Question 17

Which of the following is a correct statement about the metabolic response of skeletal muscle during intense exercise?

Accepted Answer

Glycolysis increases, and lactic acid fermentation regenerates NAD$$^+ to $$allow continued ATP production.

Question 18

Which of the following best explains why ATP is considered a universal energy currency, but not a universal explanation for growth?

Accepted Answer

Growth depends on the interaction of fuel supply, metabolic capacity, and demand/regulation, not just ATP availability.

Question 19

Which of the following best describes the main metabolic challenge faced by the brain compared to other tissues?

Accepted Answer

The brain has a high, continuous ATP demand primarily for maintaining ion gradients and signaling.

Metabolic Flexibility and Tissue-Specific Fuel Use in Organismal Growth

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