Since Mary has a Type A blood, she is either AA or AO while John is either BB or BO. Since both John's parents are Type AB, he can only have the either A or B as an allele and not O so he is BB. Since John can only give the B allele, all of his children must have the B allele in their blood types. So the adopted one is the child with type A blood.
Answer:
Due to reduced rate of egg production and several disorders caused by hormonal imbalances
Explanation:
Women lose their fertility at the age of 45 while men are able to produce sperm throughout their life. The reasons however for this are not very clear but it has been found that the rate of production of egg decreases with the advancement of age of females. Also the quality of egg degrades thereby reducing the likelihood of an egg being genetically normal. A woman along with faces several disorders due to the hormonal imbalances and one of these disorders is PCOS, ovarian insufficiency etc., which lead to distorted pattern of menstrual cycle.
Glaciers leave behind deposits known as glacial till, which are unstratified, poorly-sorted sediments. Glaciers move a wide range of sedimentary particles from small clay-sized particles to large boulders. When the glacier either melts or retreats, these poorly-sorted sediments are deposited.
