Which one of the following cells secrete heparin, histamine and serotonin?

In an antibody, disulphide bonds are present___________

i. between two heavy chains

ii. between two light chains

iii. between the constant region of light chain and the constant region of a heavy chain

iv. between antigen binding sites of both the heavy and light chains

v. between the variable region of light chain and that of heavy chain

Select the correct answer from the options given below

The water which percolates deep in the soil is ___________

Select INCORRECT statements with respects transport of $\mathrm{CO}_2$ by RBCs and plasma.

i. $23 \%$ of $\mathrm{CO}_2$ released from tissue cells diffuse into plasma first and then into RBCs.

ii. Within RBCs carbonic acid immediately dissociates into $\mathrm{H}^{+}$and $\mathrm{HCO}_3^{-}$.

iii. In RBCs $\mathrm{CO}_2$ combines with $\mathrm{H}_2 \mathrm{O}$ to form carbonic acid.

iv. $\mathrm{H}^{+}$ions move out of RBCs and combine with $\mathrm{Na}^{+}$to form $\mathrm{NaHCO}_3$.

v. $7 \%$ of $\mathrm{CO}_2$ is transported in dissolved form as carbonic acid in plasma.

In the light of above statements choose the correct answer from option given below.