BS Bachelor of Science: Science of Nutrition 2 — Questions and Answers
Question 1: Which enzyme is responsible for the initial digestion of starch in the mouth?
- Pepsin
- Salivary amylase (Correct answer)
- Lipase
- Sucrase
Correct answer: Salivary amylase
Salivary amylase (ptyalin) begins carbohydrate digestion in the oral cavity by cleaving alpha-1,4-glycosidic bonds in starch.
Question 2: The thermic effect of food (TEF) accounts for approximately what percentage of total daily energy expenditure?
- 1-3%
- 5-10% (Correct answer)
- 15-20%
- 25-30%
Correct answer: 5-10%
TEF typically represents about 5-10% of total energy expenditure and reflects the energy cost of digesting, absorbing, and metabolizing nutrients.
Question 3: Which lipoprotein is primarily responsible for transporting cholesterol from peripheral tissues back to the liver?
- Chylomicrons
- VLDL
- LDL
- HDL (Correct answer)
Correct answer: HDL
HDL (high-density lipoprotein) performs reverse cholesterol transport, collecting excess cholesterol from peripheral tissues and returning it to the liver.
Question 4: Iron absorption is significantly enhanced by which co-factor consumed in the same meal?
- Calcium
- Vitamin C (Correct answer)
- Phytate
- Oxalate
Correct answer: Vitamin C
Vitamin C (ascorbic acid) reduces ferric iron (Fe³⁺) to ferrous iron (Fe²⁺), which is more readily absorbed by intestinal enterocytes.
Question 5: Which amino acids are classified as conditionally essential during periods of physiological stress or illness?
- Leucine and isoleucine
- Glutamine and arginine (Correct answer)
- Methionine and lysine
- Phenylalanine and threonine
Correct answer: Glutamine and arginine
Glutamine and arginine become conditionally essential during critical illness or surgery because endogenous synthesis cannot meet the body's elevated demands.
Question 6: The glycemic index (GI) of a food is measured relative to which reference food?
- White bread
- Brown rice
- Pure glucose or white bread (Correct answer)
- Sucrose solution
Correct answer: Pure glucose or white bread
GI is standardized using either pure glucose (GI=100) or white bread (GI=100) as the reference, with glucose being the international standard.
Question 7: Which fatty acid is the precursor for most pro-inflammatory eicosanoids in the human body?
- Alpha-linolenic acid (ALA)
- Eicosapentaenoic acid (EPA)
- Arachidonic acid (AA) (Correct answer)
- Docosahexaenoic acid (DHA)
Correct answer: Arachidonic acid (AA)
Arachidonic acid, an omega-6 fatty acid, is the primary precursor for series-2 prostaglandins and series-4 leukotrienes, which are generally pro-inflammatory.
BS Bachelor of Science: Science of Nutrition 2
Which enzyme is responsible for the initial digestion of starch in the mouth?