Clinical Nutritionist CCN Macronutrients and Metabolism 1 — Questions and Answers
Question 1: Which metabolic pathway converts pyruvate to acetyl-CoA, linking glycolysis to the citric acid cycle?
- Pyruvate dehydrogenase reaction (Correct answer)
- Beta-oxidation
- Transamination
- Gluconeogenesis
Correct answer: Pyruvate dehydrogenase reaction
The pyruvate dehydrogenase complex irreversibly converts pyruvate to acetyl-CoA, bridging glycolysis and the TCA cycle.
Question 2: How many ATP molecules are theoretically produced from the complete oxidation of one molecule of glucose?
- 30-32 ATP (Correct answer)
- 2 ATP
- 18 ATP
- 38 ATP
Correct answer: 30-32 ATP
Complete oxidation of glucose yields approximately 30-32 ATP via glycolysis, the TCA cycle, and oxidative phosphorylation.
Question 3: Which hormone primarily stimulates lipolysis in adipose tissue during fasting?
- Glucagon (Correct answer)
- Insulin
- Leptin
- Ghrelin
Correct answer: Glucagon
Glucagon activates hormone-sensitive lipase in adipocytes, promoting the breakdown of stored triglycerides during fasting.
Question 4: The respiratory quotient (RQ) for carbohydrate oxidation is:
- 1.0 (Correct answer)
- 0.7
- 0.85
- 1.2
Correct answer: 1.0
Carbohydrate oxidation produces equal moles of CO2 and O2 consumed, giving an RQ of 1.0.
Question 5: Which amino acids are considered essential and cannot be synthesized by the human body?
- Leucine, isoleucine, valine, lysine, methionine, phenylalanine, threonine, tryptophan, histidine (Correct answer)
- Glutamine, alanine, serine, glycine, proline
- Arginine, tyrosine, cysteine, taurine
- Aspartate, glutamate, asparagine, glutamine
Correct answer: Leucine, isoleucine, valine, lysine, methionine, phenylalanine, threonine, tryptophan, histidine
Nine amino acids are essential for adults and must be obtained from diet because the body cannot synthesize them in adequate amounts.
Question 6: Which process converts excess dietary protein into glucose for energy during prolonged fasting?
- Gluconeogenesis (Correct answer)
- Glycogenolysis
- Lipogenesis
- Ketogenesis
Correct answer: Gluconeogenesis
Gluconeogenesis synthesizes glucose from glucogenic amino acids, lactate, and glycerol when carbohydrate intake is insufficient.
Clinical Nutritionist CCN Macronutrients and Metabolism 1
Which metabolic pathway converts pyruvate to acetyl-CoA, linking glycolysis to the citric acid cycle?