In erythroblastosis foetalis, which factors of the mother pass through placenta into the foetus

Loss of a $X$ chromosome in a particular cell during its development, results into

Mark the correct statement (w.r.t. sickle cell-anaemia)

Albinism is known to be due to an autosomal recessive mutation. The first child of a couple with normal skin pigmentation was an albino. What is the probability that their second child will also be an albino

Which type of pollination method was adopted by Mendel in his experiment?