$$(i)$$The two reasons for the increase of population in India are    1. Desire for a male child due to which parents continue to have children till they get a son.   2.Children are considered as earning hand in the economically weaker section. $$(ii)$$Amniotic fluid acts as the shock absorber for the growing foetus. It also prevents the sticking of the foetus to the amnion. $$(iii)$$ Ear ossicles magnify (amplify) sound vibrations and transmit it to the inner ear. $$(iv)$$ The two activities of WHO (world health organization) are 1. To set the pharmaceutical standards. 2. To suggest quarantine measures for various and contagious diseases. $$(v)$$Mendel's law of dominance explains that a dominant allele expresses itself in a monohybrid cross and suppresses the expression of recessive allele. This recessive allele for a character remain hidden or masked in the $${F}_{1}$$generation and reappears in the next generation.