ISSA Macronutrients & Micronutrients Essentials 3 — Questions and Answers
Question 1: The thermic effect of food (TEF) is highest for which macronutrient?
- Carbohydrates
- Fats
- Protein (Correct answer)
- Alcohol
Correct answer: Protein
Protein has the highest TEF at approximately 20–30%, compared to carbohydrates (5–10%) and fats (0–3%), because protein metabolism requires more energy.
Question 2: Scurvy results from a deficiency of which vitamin due to its role in collagen synthesis?
- Vitamin A
- Vitamin C (Correct answer)
- Vitamin E
- Vitamin K
Correct answer: Vitamin C
Vitamin C (ascorbic acid) is required for hydroxylation of proline and lysine residues in collagen, and its deficiency causes scurvy.
Question 3: Which type of dietary fiber is most effective at lowering LDL cholesterol by binding bile acids in the gut?
- Insoluble fiber
- Soluble fiber (Correct answer)
- Resistant starch
- Cellulose
Correct answer: Soluble fiber
Soluble fiber (e.g., beta-glucan, pectin) forms a viscous gel in the intestine that traps bile acids, increasing their fecal excretion and reducing LDL cholesterol.
Question 4: An athlete following a ketogenic diet would be relying primarily on which metabolic substrate for energy during rest and low-intensity exercise?
- Glucose from glycogen
- Ketone bodies derived from fat oxidation (Correct answer)
- Branched-chain amino acids
- Lactate from anaerobic glycolysis
Correct answer: Ketone bodies derived from fat oxidation
During ketosis, the liver produces ketone bodies (acetoacetate, beta-hydroxybutyrate) from fatty acid oxidation, which become the primary fuel when carbohydrate intake is severely restricted.
Question 5: Iron absorption from plant-based (non-heme) sources is significantly enhanced by consuming which nutrient simultaneously?
- Calcium
- Vitamin C (Correct answer)
- Phytates
- Tannins
Correct answer: Vitamin C
Vitamin C reduces ferric iron (Fe³⁺) to ferrous iron (Fe²⁺), the form that is more readily absorbed by intestinal enterocytes, enhancing non-heme iron absorption.
Question 6: Which amino acid is considered conditionally essential because demand exceeds synthesis during illness, injury, or intense training?
- Valine
- Lysine
- Glutamine (Correct answer)
- Methionine
Correct answer: Glutamine
Glutamine is normally synthesized endogenously but becomes conditionally essential under physiological stress when consumption exceeds the body's production capacity.
Question 7: Which lipoprotein is responsible for transporting dietary fat from the intestinal cells to peripheral tissues?
- VLDL
- LDL
- HDL
- Chylomicrons (Correct answer)
Correct answer: Chylomicrons
Chylomicrons are assembled in intestinal enterocytes and transport dietary triglycerides and fat-soluble vitamins via the lymphatic system to peripheral tissues.
ISSA Macronutrients & Micronutrients Essentials 3
The thermic effect of food (TEF) is highest for which macronutrient?