The trap that costs marks here: NEET regularly tests whether you can correctly sort vitamins into fat-soluble versus water-soluble groups, and whether you can link each vitamin to its specific deficiency disease. The common confusion is mixing up which vitamins are fat-soluble — students frequently misplace vitamin K into the water-soluble category, or swap the deficiency diseases between similar-sounding vitamins.
Fat-soluble vs water-soluble — the core classification.
Vitamins are classified based on their solubility. Fat-soluble vitamins — A, D, E, and K — dissolve in fats and organic solvents, are stored in liver and adipose tissue, and are not excreted easily. Water-soluble vitamins — the B-complex group (B₁, B₂, B₆, B₁₂, niacin, folic acid, biotin, pantothenic acid) and vitamin C — dissolve in water, are excreted in urine, and must be regularly replenished through diet (NCERT Class 12 Chemistry (pre-2023 edition), Chapter 14, page 432).
Key vitamin–deficiency pairs tested in NEET:
Watch out: The biomolecules bundle pattern in NEET (observed 2021–2025) frequently places a vitamin classification or deficiency question alongside carbohydrate/protein questions. The distractor strategy is swapped-class options — putting a B-complex vitamin among fat-soluble choices, or assigning scurvy to the wrong vitamin.
Select an option to see the explanation. Wrong answers show why your choice was tempting — and name the exact trap it exploits.
Which of the following is NOT a fat-soluble vitamin?
Answer: B. Vitamin B₁₂ (cobalamin) is a water-soluble vitamin belonging to the B-complex group. The four fat-soluble vitamins are A, D, E, and K (NCERT Class 12 Chemistry (pre-2023 edition), Chapter 14, page 432).
Why A is wrong: A is wrong — Vitamin A is fat-soluble, stored in the liver; it is not water-soluble.
Why C is wrong: C is wrong — Vitamin D is fat-soluble, synthesised in skin via UV exposure and stored in adipose tissue.
Why D is wrong: D is wrong — Vitamin K is fat-soluble, essential for blood clotting; a common trap is placing it among water-soluble vitamins.
Deficiency of which vitamin causes scurvy?
Answer: B. Scurvy — characterised by bleeding gums, swollen joints, and poor wound healing — results from deficiency of vitamin C (ascorbic acid), a water-soluble vitamin (NCERT Class 12 Chemistry (pre-2023 edition), Chapter 14, page 432).
Why A is wrong: A is wrong — Vitamin A deficiency causes xerophthalmia (night blindness), not scurvy. Swapping deficiency diseases between vitamins is a common distractor.
Why C is wrong: C is wrong — Vitamin D deficiency causes rickets in children and osteomalacia in adults, not scurvy.
Why D is wrong: D is wrong — Vitamin B₁ (thiamine) deficiency causes beri-beri, not scurvy. The B₁/C swap is a frequent NEET distractor.
Which vitamin deficiency leads to beri-beri?
Answer: A. Beri-beri is caused by deficiency of vitamin B₁ (thiamine). It manifests as peripheral neuropathy and cardiovascular complications (NCERT Class 12 Chemistry (pre-2023 edition), Chapter 14, page 432).
Why B is wrong: B is wrong — Vitamin B₂ (riboflavin) deficiency causes cheilosis (cracking at corners of mouth) and glossitis, not beri-beri.
Why C is wrong: C is wrong — Niacin (B₃) deficiency causes pellagra (dermatitis, diarrhoea, dementia), not beri-beri. The B-vitamin deficiency swap is a common distractor.
Why D is wrong: D is wrong — Vitamin B₆ (pyridoxine) deficiency causes convulsions and dermatitis, not beri-beri.
A patient presents with delayed blood clotting after injury. The physician suspects a vitamin deficiency. Which vitamin is most likely deficient?
Answer: C. Vitamin K is essential for the synthesis of prothrombin and other clotting factors in the liver. Its deficiency leads to delayed blood clotting and excessive bleeding (NCERT Class 12 Chemistry (pre-2023 edition), Chapter 14, page 432).
Why A is wrong: A is wrong — Vitamin E deficiency causes reproductive disorders and muscular dystrophy, not clotting defects. The K/E swap exploits the fact that both are fat-soluble.
Why B is wrong: B is wrong — Vitamin C deficiency causes scurvy (bleeding gums), but this is due to weakened connective tissue, not a defect in the clotting cascade itself.
Why D is wrong: D is wrong — Vitamin D deficiency causes rickets/osteomalacia (bone disorders), not clotting problems.
Fat-soluble vitamins are stored in the body and can accumulate to toxic levels (hypervitaminosis). Which group of vitamins carries this risk?
Answer: B. All four fat-soluble vitamins — A, D, E, and K — are stored in the liver and adipose tissue and can accumulate, posing a risk of hypervitaminosis. Water-soluble vitamins are excreted in urine and rarely accumulate (NCERT Class 12 Chemistry (pre-2023 edition), Chapter 14, page 432).
Why A is wrong: A is wrong — B-complex and C are water-soluble; they are excreted via urine and do not accumulate to toxic levels under normal conditions.
Why C is wrong: C is wrong — While A and D are the most commonly cited for toxicity, E and K are also fat-soluble and can accumulate. The question asks about the complete group at risk.
Why D is wrong: D is wrong — B₁₂ is water-soluble despite being stored to some extent in the liver. It does not belong to the fat-soluble group. Inserting B₁₂ among fat-soluble vitamins is a classic swapped-class distractor.
Pellagra is characterised by dermatitis, diarrhoea, and dementia. It is caused by deficiency of:
Answer: C. Pellagra, with its classic "3 Ds" — dermatitis, diarrhoea, dementia — is caused by deficiency of niacin (vitamin B₃ / nicotinic acid) (NCERT Class 12 Chemistry (pre-2023 edition), Chapter 14, page 432).
Why A is wrong: A is wrong — Thiamine (B₁) deficiency causes beri-beri, not pellagra. Both are B-complex vitamins, making this a tempting swap.
Why B is wrong: B is wrong — Riboflavin (B₂) deficiency causes cheilosis and photophobia, not pellagra.
Why D is wrong: D is wrong — Ascorbic acid (vitamin C) deficiency causes scurvy, not pellagra. Scurvy involves bleeding gums and connective tissue weakness, not the 3-D triad.
A student claims: "Since water-soluble vitamins are not stored, they cannot cause any harm even in large doses." Which of the following best addresses this claim?
Answer: D. While water-soluble vitamins are generally excreted in urine and do not accumulate like fat-soluble ones, the blanket statement "cannot cause any harm" is an oversimplification. Extremely high doses can cause adverse effects (e.g., oxalate kidney stones from megadoses of vitamin C). The claim is mostly correct in principle but overstated.
Why A is wrong: A is wrong — Saying 'completely safe at any dose' is an absolute claim. While the risk is low, extremely high doses of water-soluble vitamins can cause adverse effects.
Why B is wrong: B is wrong — Fat-soluble vitamins (A, D) are far more associated with toxicity from accumulation. Water-soluble vitamins are less toxic, not more.
Why C is wrong: C is wrong — Water-soluble vitamins are NOT stored like fat-soluble vitamins. They are indeed excreted in urine. The issue with the original claim is its absoluteness, not its premise about storage.
Vitamins A and D are both fat-soluble, yet their deficiency diseases affect entirely different organ systems. Which pair correctly matches each vitamin to the primary system affected by its deficiency?
Answer: A. Vitamin A deficiency primarily affects the visual system (xerophthalmia, night blindness), while vitamin D deficiency primarily affects the skeletal system (rickets, osteomalacia) (NCERT Class 12 Chemistry (pre-2023 edition), Chapter 14, page 432).
Why B is wrong: B is wrong — This reverses the correct pairing. Vitamin A affects vision, not bones; vitamin D affects bones, not vision. The A/D deficiency-disease swap is a high-frequency NEET distractor.
Why C is wrong: C is wrong — Neither the circulatory nor nervous system is the primary target. Vitamin K (not A) is linked to clotting (circulatory), and B-complex vitamins (not D) are more associated with neurological deficits.
Why D is wrong: D is wrong — Reproductive system involvement is associated with vitamin E deficiency, and muscular dystrophy is also linked to vitamin E. Neither A nor D primarily targets these systems.
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Given
Four statements linking vitamins to their solubility class or deficiency disease.
Required
Identify the single correct statement.
Concept
Vitamins are classified as fat-soluble (A, D, E, K) or water-soluble (B-complex, C). Each vitamin has a characteristic deficiency disease.
Formula
No numerical formula applies. This is a classification-and-recall problem.
Substitution
Evaluate each statement against known vitamin facts:
• (i) Vitamin C → water-soluble, NOT fat-soluble. Incorrect.• (ii) Vitamin K → deficiency causes delayed clotting/haemorrhage, NOT rickets. Rickets is vitamin D deficiency. Incorrect.• (iii) Vitamin B₁ (thiamine) → deficiency causes beri-beri. Correct.• (iv) Vitamin D → fat-soluble, NOT water-soluble. Incorrect.
Calculation
No calculation needed. Direct comparison of each statement against established vitamin classification and deficiency data.
Final answer
Statement (iii) is correct — vitamin B₁ deficiency causes beri-beri.
Common trap
Statement (ii) exploits the K/D deficiency swap — students who vaguely recall "a fat-soluble vitamin causes rickets" may pick K instead of D. Statement (i) exploits the solubility confusion — vitamin C sounds like it could be stored because of its importance, but it is water-soluble and excreted.
Similar NEET-style question
"Which of the following pairs is correctly matched?
(A) Vitamin A — Beri-beri
(B) Vitamin D — Scurvy
(C) Vitamin K — Blood clotting
(D) Niacin — Night blindness"
Answer: (C). Vitamin K is essential for blood clotting. The other three pairs are deliberately swapped.
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Organic compounds required in small amounts for metabolism, cannot be synthesized in body. Fat-soluble: A, D, E, K. Water-soluble: B-complex, C. Each prevents specific deficiency disease.
-- NCERT Class 12 Chemistry (pre-2023 edition), Chapter 14, p. 426More in Biomolecules: 4 exam traps and mistakes · 3 formulas from its other lessons.
3 questions from NEET 2021, 2025, 2026. Answers verified against NTA official keys.
The RBC efficiency is deficiency disease of :
Recurring question shapes from past papers. Each pattern shows why wrong options look tempting.
swapped classes
Tempts surface-level recall.
Page numbers are the ones printed in the current NCERT textbook (2023 rationalised edition), unless marked pre-2023. The books are free at ncert.nic.in.
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