Q. 1. How are vitamins classified ? Name the vitamin responsible for the coagulation of blood.
Ans. Vitamins are classified as :
(i) Water-soluble vitamins : B and C are the water soluble vitamins.
(ii) Oil or fat-soluble vitamins : Vitamins A, D, E and F are oil (or fat soluble).
Vitamin K is responsible for the coagulation of blood.
Q. 2. Why are vitamin A and vitamin C essential to us ? Give their important sources.
Ans. (i) The chemical name of vitamin A is retinol.
Important Sources of Vitamin ‘A’: Milk, butter, egg, fish and fish oil (Cod liver oil). It can also be synthesised in the body from carotenoids present in carrots, tomatoes, ripe mangoes etc. Carotenoids are the precursors of vitamin A.
(ii) The chemical name of vitamin C is ascorbic acid.
Important Sources of Vitamin C : Citrus fruits (oranges, lemon, grape fruit, lime etc.).
Q. 3. What are nucleic acids ? Mention their two important functions.
Ans. Nucleic acids are complex acids occuring in all living cells and are composed of a phosphoric acid group, a carbohydrate, two purines and two pyrimidines.
Functions: (i) Development and reproduction of all forms of life.
(ii) Synthesis of proteins and are responsible for the transfer of genetic information i.e., the hereditary characteristics.
Q. 4. What are polysaccharides ? Name one of them. How is it important to us ?
Ans. Polysaccharides are carbohydrates which on hydrolysis gives hundreds or even thousands of monosaccharides units. Cellulose in an example of polysaccharide. Cellulose is important to us in the following ways :
(i) It is used in the manufacture of rayon and gun cotton (explosive).
(ii) It is used in the manufacture of cellotape and cellophone paper.
(iii) It is used in the manufacture of nitrocellulose (used as rocket propellant).
Q. 5. What are biodegradable and non-biode gradable detergents ? Give one example of each.
Ans. Biodegradable detergents are detergents with straight hydrocarbon chain. These detergents can be destroyed by bacteria. Non-biodegradable detergents are