IIN Nutrition Science 3 — Questions and Answers
Question 1: Which macronutrient provides 9 calories per gram?
- Protein
- Carbohydrate
- Fat (Correct answer)
- Alcohol
Correct answer: Fat
Dietary fat is the most energy-dense macronutrient, providing 9 kcal per gram compared to 4 kcal/g for protein and carbohydrate.
Question 2: What is the role of secretory IgA (sIgA) in gut health?
- It digests dietary fiber into short-chain fatty acids
- It is the primary antibody defending mucosal surfaces from pathogens (Correct answer)
- It transports fat-soluble vitamins across the gut wall
- It regulates gastric acid secretion
Correct answer: It is the primary antibody defending mucosal surfaces from pathogens
Secretory IgA is the dominant immunoglobulin in the gut lumen and protects mucosal surfaces by neutralizing pathogens and toxins.
Question 3: Which mineral deficiency is most commonly associated with goiter (enlarged thyroid gland)?
- Iron
- Calcium
- Iodine (Correct answer)
- Zinc
Correct answer: Iodine
Iodine is essential for thyroid hormone synthesis; deficiency causes the thyroid gland to enlarge in an attempt to capture more iodine from the blood.
Question 4: Short-chain fatty acids (SCFAs) like butyrate, propionate, and acetate are produced when gut bacteria ferment:
- Saturated fats
- Dietary fiber and resistant starch (Correct answer)
- Dietary proteins
- Simple sugars like sucrose
Correct answer: Dietary fiber and resistant starch
Gut microbiota ferment indigestible dietary fiber and resistant starch to produce SCFAs, which nourish colonocytes and support gut health.
Question 5: According to IIN's 'Plate' approach, which component should make up the largest portion of a healthy meal?
- Lean animal proteins
- Whole grains and starches
- Non-starchy vegetables (Correct answer)
- Healthy fats and oils
Correct answer: Non-starchy vegetables
IIN emphasizes filling half or more of the plate with non-starchy vegetables to maximize micronutrient and fiber intake.
Question 6: Which form of iron is more bioavailable and is found in animal foods?
- Non-heme iron
- Ferrous sulfate iron
- Heme iron (Correct answer)
- Ferric iron
Correct answer: Heme iron
Heme iron, found in hemoglobin and myoglobin in meat and fish, is absorbed at a rate of 15–35%, far higher than non-heme iron from plant sources.
Question 7: What is the main difference between soluble and insoluble dietary fiber?
- Soluble fiber is only found in animal foods; insoluble is plant-based
- Soluble fiber dissolves in water and forms a gel; insoluble fiber adds bulk and speeds transit (Correct answer)
- Insoluble fiber lowers cholesterol; soluble fiber prevents constipation
- Soluble fiber is digested by human enzymes; insoluble is not
Correct answer: Soluble fiber dissolves in water and forms a gel; insoluble fiber adds bulk and speeds transit
Soluble fiber (e.g., pectin, beta-glucan) dissolves in water to form a viscous gel that slows digestion and lowers cholesterol, while insoluble fiber (e.g., cellulose) adds stool bulk.
IIN Nutrition Science 3
Which macronutrient provides 9 calories per gram?