Given below are two statements, one is labelled as Assertion (A) and other as Reason (R): Assertion (A): Human body synthesises all the vitamins required by it. Reason (R): Vitamins are essential for proper growth of the body. Select the correct answer using the codes given below.
- (a)Both (A) and (R) are true and (R) is correct explanation of (A)
- (b)Both (A) and (R) are true, but (R) is not correct explanation of (A)
- (c)(A) is true, but (R) is false
- (d)(A) is false, but (R) is true
Correct — D, (A) is false but (R) is true. Assertion (A) is FALSE: the human body cannot synthesise all the vitamins it needs. It makes only a few — vitamin D in the skin using sunlight, and small amounts of vitamin K and some B-vitamins with the help of gut bacteria — while most vitamins (notably vitamin C, vitamin A and most B-vitamins) must be obtained from the diet. Reason (R) is TRUE: vitamins are indeed essential micronutrients required for proper growth, metabolism and immunity. Since A is false and R is true, the correct code is (d).
- (a)Both (A) and (R) are true and (R) is correct explanation of (A) — Wrong — (A) is not true; the body cannot synthesise all vitamins, so most (like vitamin C) must come from food. A false assertion cannot be 'explained' by R.
- (b)Both (A) and (R) are true, but (R) is not correct explanation of (A) — Wrong — this again treats (A) as true, but the body does not make all its own vitamins, so (A) is false.
- (c)(A) is true, but (R) is false — Wrong on both counts — (A) is false (the body can't synthesise all vitamins) and (R) is true (vitamins are essential for growth).
Vitamins are organic micronutrients that the body needs in tiny amounts for growth, metabolism and health, but which it largely cannot manufacture itself — so they must be supplied by the diet. Only a handful are made internally: vitamin D (synthesised in skin on exposure to sunlight), and vitamin K plus a few B-vitamins (partly produced by intestinal bacteria). Their deficiency causes specific diseases (e.g. vitamin C → scurvy, vitamin D → rickets).
In an Assertion–Reason item, test each statement independently first. R ('vitamins are essential for growth') is clearly true. A ('body synthesises ALL vitamins') is a classic false blanket claim — the word 'all' is the trap, since humans famously cannot make vitamin C. With A false and R true, only code (d) fits.
- Most vitamins are dietary essentials — the human body cannot synthesise them.
- Humans cannot make vitamin C (they lack the enzyme L-gulonolactone oxidase); it must come from food.
- Vitamin D is synthesised in the skin using sunlight; vitamin K and some B-vitamins are partly made by gut bacteria.
- Vitamins are classified as fat-soluble (A, D, E, K) and water-soluble (B-complex, C).
- The absolute word 'all' — the body makes only a few vitamins, not all
- Marking (a)/(b) by assuming the assertion is true because the reason sounds correct
UPSC & UPPSC test this either as an Assertion–Reason (spot the false 'all' claim) or by pairing a vitamin with its deficiency disease or its source.
Assertion (A): Human diet should compulsorily contain Glycerine, Serine and Tyrosine. Reason (R): Essential amino acids cannot be synthesised in the human body.
- (a) Both A and R are individually true and R is the correct explanation of A
- (b) Both A and R are individually true but R is not a correct explanation of A
- (c) A is true but R is false
- (d) A is false but R is true
Answer(d) A is false but R is true
Same Assertion–Reason format and the same core idea — the human body cannot synthesise every nutrient it needs; here it is amino acids, and the answer is again (d) A false, R true.
- practice — not a real PYQ
Which one of the following vitamins is synthesised in the human skin in the presence of sunlight?
- (a)Vitamin A
- (b)Vitamin C
- (c)Vitamin D
- (d)Vitamin B12
Answer(c) Vitamin D — produced in the skin from a cholesterol derivative on exposure to ultraviolet sunlight.
- practice — not a real PYQ
Deficiency of which vitamin causes the disease scurvy?
- (a)Vitamin A
- (b)Vitamin C
- (c)Vitamin D
- (d)Vitamin K
Answer(b) Vitamin C (ascorbic acid) — humans cannot synthesise it, and its lack causes scurvy.