Clinical Nutritionist CCN Macronutrients and Metabolism

Question 1

Which metabolic pathway converts pyruvate to acetyl-CoA, linking glycolysis to the citric acid cycle?

Accepted Answer

Pyruvate dehydrogenase reaction

Answer

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?

Accepted Answer

30-32 ATP

Answer

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?

Accepted Answer

Glucagon

Answer

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:

Accepted Answer

1.0

Answer

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?

Accepted Answer

Leucine, isoleucine, valine, lysine, methionine, phenylalanine, threonine, tryptophan, histidine

Answer

Nine amino acids are essential for adults and must be obtained from diet because the body cannot synthesize them in adequate amounts.

Clinical Nutritionist CCN Practice Test