NFS EXAM ONE 2026 COMPLETE REVIEW –
COMBINED QUIZZES TEST BANK WITH
VERIFIED ANSWERS & DETAILED SOLUTIONS |
PASS-FOCUSED STUDY GUIDE
1. Which lipoprotein particle is assembled in the liver and delivers endogenous triglycerides
to peripheral tissues?
• A. Chylomicron
• B. HDL
• C. VLDL (Very Low-Density Lipoprotein)
• D. IDL
RATIONALE: VLDL is synthesized in the liver and exports endogenous triglycerides
(from de novo lipogenesis and re-esterified FFAs) to peripheral tissues. Lipoprotein lipase (LPL)
on capillary endothelium hydrolyzes VLDL-TG, releasing fatty acids for uptake. Remnant VLDL
becomes IDL, then LDL.
2. The biological value (BV) of a protein measures:
• A. The rate at which a protein is digested in the small intestine
• B. The total amino acid content per gram of protein
• C. The proportion of absorbed nitrogen retained in the body for growth and
maintenance
• D. The digestibility of a protein corrected for amino acid score
RATIONALE: BV = (Nitrogen retained ÷ Nitrogen absorbed) × 100. It reflects how
efficiently absorbed protein nitrogen is utilized for tissue synthesis. Egg has BV ~100, whey
~104 (>100 reflects methodological differences), soy ~74, wheat ~54. BV does not account for
digestibility — PDCAAS and DIAAS are more complete measures.
3. Which enzyme catalyzes the rate-limiting step of the urea cycle in the mitochondria?
• A. Ornithine transcarbamylase
• B. Arginase
• C. Carbamoyl phosphate synthetase I (CPS-I)
, • D. Argininosuccinate synthetase
RATIONALE: CPS-I catalyzes the first committed step of the urea cycle: NH₃ + CO₂ + 2
ATP → carbamoyl phosphate. It is activated allosterically by N-acetylglutamate (NAG), which is
synthesized when amino acid catabolism increases. CPS-I deficiency causes severe neonatal
hyperammonemia.
4. A patient consuming a diet chronically high in raw egg whites develops which deficiency?
• A. Thiamine deficiency
• B. Riboflavin deficiency
• C. Biotin deficiency
• D. Niacin deficiency
RATIONALE: Raw egg whites contain avidin, a glycoprotein that binds biotin with
extremely high affinity (Kd ~10⁻¹⁵ M), preventing intestinal absorption. Cooking denatures
avidin, eliminating this effect. Biotin deficiency causes alopecia, dermatitis, neurological
symptoms, and conjunctivitis.
5. The primary form in which dietary fat is absorbed across the intestinal brush border is:
• A. Intact triglycerides via receptor-mediated endocytosis
• B. Free fatty acids only after complete triglyceride hydrolysis
• C. Free fatty acids and 2-monoglycerides diffusing from mixed micelles
• D. Chylomicrons formed in the intestinal lumen before absorption
RATIONALE: Pancreatic lipase (with colipase) cleaves triglycerides at sn-1 and sn-3
positions, releasing 2 free fatty acids and one 2-monoglyceride. These products are incorporated
into mixed micelles with bile salts and diffuse passively across the brush border. Inside
enterocytes, triglycerides are re-synthesized via the monoacylglycerol pathway.
6. Vitamin K2 (menaquinones) differs from vitamin K1 (phylloquinone) in that:
• A. Vitamin K2 is exclusively found in plant-based foods
, • B. Vitamin K2 is produced by gut bacteria and found in fermented foods; it may
have stronger extrahepatic (bone, vascular) effects
• C. Vitamin K2 cannot support blood coagulation
• D. Vitamin K2 is water-soluble and does not require fat for absorption
RATIONALE: Vitamin K2 (MK-4 to MK-13) is found in fermented foods (natto, cheese)
and produced by gut bacteria. Research suggests MK-7 (long-chain) has greater bioavailability
and half-life than K1. K2 may preferentially activate matrix Gla protein (MGP) — an inhibitor of
vascular calcification — and osteocalcin for bone mineralization.
7. Which fatty acid is the primary precursor to arachidonic acid via elongation and
desaturation?
• A. Alpha-linolenic acid (18:3 ω-3)
• B. Linoleic acid (18:2 ω-6)
• C. Eicosapentaenoic acid (20:5 ω-3)
• D. Palmitoleic acid (16:1 ω-7)
RATIONALE: Linoleic acid (LA, 18:2 ω-6) is elongated to dihomo-gamma-linolenic
acid (DGLA, 20:3 ω-6) and then desaturated by Δ5-desaturase to arachidonic acid (AA, 20:4 ω-
6). AA is a precursor to pro-inflammatory eicosanoids (PGE2, LTB4). Competing ω-3 fatty acids
reduce AA-derived eicosanoid synthesis.
8. The condition xerophthalmia progresses in which order?
• A. Bitot's spots → Night blindness → Corneal ulceration → Keratomalacia
• B. Night blindness → Conjunctival xerosis → Bitot's spots → Corneal xerosis →
Corneal ulceration → Keratomalacia
• C. Keratomalacia → Corneal ulceration → Bitot's spots → Night blindness
• D. Corneal xerosis → Night blindness → Bitot's spots → Corneal ulceration
RATIONALE: WHO stages xerophthalmia (vitamin A deficiency eye disease) as: XN
(night blindness) → X1A (conjunctival xerosis) → X1B (Bitot's spots) → X2 (corneal xerosis)
→ X3A (corneal ulceration <1/3 cornea) → X3B (keratomalacia ≥1/3 cornea) → XS (corneal
, scar) → XF (xerophthalmic fundus). Early stages are reversible; keratomalacia causes permanent
blindness.
9. Osteomalacia in adults and rickets in children are caused by which fundamental
biochemical defect?
• A. Insufficient dietary calcium with normal vitamin D status
• B. Impaired mineralization of osteoid matrix due to deficient calcitriol-mediated
calcium and phosphate availability
• C. Excess parathyroid hormone causing bone resorption
• D. Vitamin K deficiency impairing osteocalcin carboxylation
RATIONALE: Rickets/osteomalacia result from inadequate calcium-phosphate product
for hydroxyapatite deposition into osteoid. This occurs with vitamin D deficiency (impaired
intestinal Ca/P absorption), vitamin D-resistant rickets (VDR mutations), or dietary
calcium/phosphate deficiency. Unmineralized osteoid matrix causes soft, deformable bone.
10. The limiting amino acid in maize (corn) is:
• A. Leucine
• B. Valine
• C. Lysine (and tryptophan)
• D. Threonine
RATIONALE: Maize is deficient in lysine and tryptophan (which can be converted to
niacin). Populations dependent on maize without nixtamalization (alkali processing that releases
niacin) or dietary complementation develop pellagra (niacin deficiency). Opaque-2 maize and
Quality Protein Maize (QPM) were biofortified to increase lysine content.
11. Glycine is classified as a non-essential amino acid but becomes conditionally essential in
which situation?
• A. During any low-protein diet
COMBINED QUIZZES TEST BANK WITH
VERIFIED ANSWERS & DETAILED SOLUTIONS |
PASS-FOCUSED STUDY GUIDE
1. Which lipoprotein particle is assembled in the liver and delivers endogenous triglycerides
to peripheral tissues?
• A. Chylomicron
• B. HDL
• C. VLDL (Very Low-Density Lipoprotein)
• D. IDL
RATIONALE: VLDL is synthesized in the liver and exports endogenous triglycerides
(from de novo lipogenesis and re-esterified FFAs) to peripheral tissues. Lipoprotein lipase (LPL)
on capillary endothelium hydrolyzes VLDL-TG, releasing fatty acids for uptake. Remnant VLDL
becomes IDL, then LDL.
2. The biological value (BV) of a protein measures:
• A. The rate at which a protein is digested in the small intestine
• B. The total amino acid content per gram of protein
• C. The proportion of absorbed nitrogen retained in the body for growth and
maintenance
• D. The digestibility of a protein corrected for amino acid score
RATIONALE: BV = (Nitrogen retained ÷ Nitrogen absorbed) × 100. It reflects how
efficiently absorbed protein nitrogen is utilized for tissue synthesis. Egg has BV ~100, whey
~104 (>100 reflects methodological differences), soy ~74, wheat ~54. BV does not account for
digestibility — PDCAAS and DIAAS are more complete measures.
3. Which enzyme catalyzes the rate-limiting step of the urea cycle in the mitochondria?
• A. Ornithine transcarbamylase
• B. Arginase
• C. Carbamoyl phosphate synthetase I (CPS-I)
, • D. Argininosuccinate synthetase
RATIONALE: CPS-I catalyzes the first committed step of the urea cycle: NH₃ + CO₂ + 2
ATP → carbamoyl phosphate. It is activated allosterically by N-acetylglutamate (NAG), which is
synthesized when amino acid catabolism increases. CPS-I deficiency causes severe neonatal
hyperammonemia.
4. A patient consuming a diet chronically high in raw egg whites develops which deficiency?
• A. Thiamine deficiency
• B. Riboflavin deficiency
• C. Biotin deficiency
• D. Niacin deficiency
RATIONALE: Raw egg whites contain avidin, a glycoprotein that binds biotin with
extremely high affinity (Kd ~10⁻¹⁵ M), preventing intestinal absorption. Cooking denatures
avidin, eliminating this effect. Biotin deficiency causes alopecia, dermatitis, neurological
symptoms, and conjunctivitis.
5. The primary form in which dietary fat is absorbed across the intestinal brush border is:
• A. Intact triglycerides via receptor-mediated endocytosis
• B. Free fatty acids only after complete triglyceride hydrolysis
• C. Free fatty acids and 2-monoglycerides diffusing from mixed micelles
• D. Chylomicrons formed in the intestinal lumen before absorption
RATIONALE: Pancreatic lipase (with colipase) cleaves triglycerides at sn-1 and sn-3
positions, releasing 2 free fatty acids and one 2-monoglyceride. These products are incorporated
into mixed micelles with bile salts and diffuse passively across the brush border. Inside
enterocytes, triglycerides are re-synthesized via the monoacylglycerol pathway.
6. Vitamin K2 (menaquinones) differs from vitamin K1 (phylloquinone) in that:
• A. Vitamin K2 is exclusively found in plant-based foods
, • B. Vitamin K2 is produced by gut bacteria and found in fermented foods; it may
have stronger extrahepatic (bone, vascular) effects
• C. Vitamin K2 cannot support blood coagulation
• D. Vitamin K2 is water-soluble and does not require fat for absorption
RATIONALE: Vitamin K2 (MK-4 to MK-13) is found in fermented foods (natto, cheese)
and produced by gut bacteria. Research suggests MK-7 (long-chain) has greater bioavailability
and half-life than K1. K2 may preferentially activate matrix Gla protein (MGP) — an inhibitor of
vascular calcification — and osteocalcin for bone mineralization.
7. Which fatty acid is the primary precursor to arachidonic acid via elongation and
desaturation?
• A. Alpha-linolenic acid (18:3 ω-3)
• B. Linoleic acid (18:2 ω-6)
• C. Eicosapentaenoic acid (20:5 ω-3)
• D. Palmitoleic acid (16:1 ω-7)
RATIONALE: Linoleic acid (LA, 18:2 ω-6) is elongated to dihomo-gamma-linolenic
acid (DGLA, 20:3 ω-6) and then desaturated by Δ5-desaturase to arachidonic acid (AA, 20:4 ω-
6). AA is a precursor to pro-inflammatory eicosanoids (PGE2, LTB4). Competing ω-3 fatty acids
reduce AA-derived eicosanoid synthesis.
8. The condition xerophthalmia progresses in which order?
• A. Bitot's spots → Night blindness → Corneal ulceration → Keratomalacia
• B. Night blindness → Conjunctival xerosis → Bitot's spots → Corneal xerosis →
Corneal ulceration → Keratomalacia
• C. Keratomalacia → Corneal ulceration → Bitot's spots → Night blindness
• D. Corneal xerosis → Night blindness → Bitot's spots → Corneal ulceration
RATIONALE: WHO stages xerophthalmia (vitamin A deficiency eye disease) as: XN
(night blindness) → X1A (conjunctival xerosis) → X1B (Bitot's spots) → X2 (corneal xerosis)
→ X3A (corneal ulceration <1/3 cornea) → X3B (keratomalacia ≥1/3 cornea) → XS (corneal
, scar) → XF (xerophthalmic fundus). Early stages are reversible; keratomalacia causes permanent
blindness.
9. Osteomalacia in adults and rickets in children are caused by which fundamental
biochemical defect?
• A. Insufficient dietary calcium with normal vitamin D status
• B. Impaired mineralization of osteoid matrix due to deficient calcitriol-mediated
calcium and phosphate availability
• C. Excess parathyroid hormone causing bone resorption
• D. Vitamin K deficiency impairing osteocalcin carboxylation
RATIONALE: Rickets/osteomalacia result from inadequate calcium-phosphate product
for hydroxyapatite deposition into osteoid. This occurs with vitamin D deficiency (impaired
intestinal Ca/P absorption), vitamin D-resistant rickets (VDR mutations), or dietary
calcium/phosphate deficiency. Unmineralized osteoid matrix causes soft, deformable bone.
10. The limiting amino acid in maize (corn) is:
• A. Leucine
• B. Valine
• C. Lysine (and tryptophan)
• D. Threonine
RATIONALE: Maize is deficient in lysine and tryptophan (which can be converted to
niacin). Populations dependent on maize without nixtamalization (alkali processing that releases
niacin) or dietary complementation develop pellagra (niacin deficiency). Opaque-2 maize and
Quality Protein Maize (QPM) were biofortified to increase lysine content.
11. Glycine is classified as a non-essential amino acid but becomes conditionally essential in
which situation?
• A. During any low-protein diet
