Q3. How did vitamins get their name, and why was the spelling changed?
They were called “vitamines”, from vital + amine, because the first ones identified had amino groups. Later work showed that most have no amino group, so the final “e” was dropped (NCERT page 296).
Q4. Vitamins are called essential food factors. Name two ways in which we get vitamins without eating them directly as vitamins.
Bacteria in the gut produce some of the vitamins we need (NCERT page 295), and exposure to sunlight is a source of vitamin D (NCERT Table 10.3, page 296).
Q5. Why can large doses of fat-soluble vitamins do more lasting harm than large doses of most water-soluble ones?
Fat-soluble vitamins are stored in the liver and fat tissue, so an excess builds up. Water-soluble vitamins, except B12, are readily excreted in urine. NCERT warns that an excess of vitamins is harmful (NCERT page 296; reasoned).
Q6. Fissuring at the corners of the mouth and lips points to a lack of which vitamin? Give two sources.
Vitamin B2 (riboflavin); the condition is cheilosis. Sources: milk, egg white, liver and kidney (NCERT Table 10.3, page 296).