Enumerate any four functions of blood.

Explanation

(a) DNA is a polynucleotide. Each nucleotide contains
(i) A sugar molecule - Deoxyribose sugar
(ii) A nitrogenous base. They are two types of nitrogeneous bases. They are
1. Purines (Adenine and Guanine) `" "` 2. Pyrimidines (Cytosine and Thymine)
(iii) A phosphate group
Nucleoside = Nitrogen base + sugar
Nucleotide = Nucleotide + Phosphate
Purines and Pyrimidines are linked by hydrogen bonds.
Adenine (A) links thymine (T) with two hydrogen bonds (A = T)
Cytosine (C) links Guanine (G) with three hydrogen bonds `(C equiv G)`
(b) Functions of blood:
(i) Transport of respiratory gases (Oxygen and `CO_(2)`).
(ii) Transport of hormones.
(iii) It maintains proper water balance in the body.
(iv) It acts as buffer and also helps in regulation of pH and body temperature.