What are vitamins? How are they classified? Name the deficiency diseases caused by lack of vitamins A, C and D.

1. 1 · Define. Organic compounds needed in small amounts in the diet; their lack causes specific deficiency diseases.
2. 2 · Fat-soluble vitamins. A, D, E, K: stored in the liver and adipose tissue.
3. 3 · Water-soluble vitamins. B group and C: excreted in urine, so needed regularly (except B₁₂, which is stored).
4. 4 · Name the diseases.
   • A: xerophthalmia, night blindness
   • C: scurvy (bleeding gums)
   • D: rickets in children, osteomalacia in adults
5. 5 · Link to real life. Amla gives vitamin C; a little morning sunlight helps the skin make vitamin D.
6. 6 · Close in one line. So vitamins are classified by solubility, which also decides how often we need them.

Scoring tip: Write the classification as two labelled lists, then one disease per vitamin. Spell xerophthalmia carefully.