Clinical Nutritionist CCN Macronutrients and Metabolism 2

Question 1

Which lipoprotein is responsible for transporting cholesterol from peripheral tissues back to the liver?

Accepted Answer

HDL

Answer

High-density lipoprotein (HDL) mediates reverse cholesterol transport, carrying excess cholesterol from tissues to the liver for excretion.

Question 2

What is the primary fuel source for the brain under normal fed conditions?

Accepted Answer

Glucose

Answer

The brain relies almost exclusively on glucose for energy under normal conditions because fatty acids cannot cross the blood-brain barrier efficiently.

Question 3

During beta-oxidation of a 16-carbon saturated fatty acid, how many acetyl-CoA molecules are produced?

Accepted Answer

8

Answer

Each round of beta-oxidation cleaves a 2-carbon acetyl-CoA unit, so a 16-carbon fatty acid yields 8 acetyl-CoA molecules.

Question 4

Which enzyme is the rate-limiting step of fatty acid synthesis?

Accepted Answer

Acetyl-CoA carboxylase

Answer

Acetyl-CoA carboxylase catalyzes the carboxylation of acetyl-CoA to malonyl-CoA, the committed and rate-limiting step in fatty acid synthesis.

Question 5

What is the thermic effect of food (TEF) for dietary protein compared to carbohydrates and fat?

Accepted Answer

20-30% for protein vs 5-10% for carbs and 0-3% for fat

Answer

Protein has the highest thermic effect (20-30%), meaning it requires the most energy to digest, absorb, and metabolize compared to other macronutrients.

Clinical Nutritionist CCN Practice Test

Clinical Nutritionist CCN Practice Test

Clinical Nutritionist CCN Macronutrients and Metabolism 2