The correct answer is meiosis. This is because a zygote is a 2n diploid cell caused by human fertilization witch is meiosis. This shows that the correct answer is meiosis. There are two things needed witch are the two gametes. These two gametes are called the egg(female) and the sperm(male).
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Loss of habitat from human civilizations
Traits that are passed down on an X or a Y chromosome are sex-linked traits. Most of the time males are affected by sex-linked traits because males only have one X and a Y. The Y is the chromosome that makes a man, a man.
The right answer is D (less responsive to antigens)
It is proven that, after puberty, thymus activity (an organ that is included in the lymphatic system, producing T cells that pick up antigens) decreases and that in adult and aged people the thymus has no role. Work done in humans indicate that in fact the cellularity begins to decline from birth in favor of lymphocyte perivascular spaces and connective and adipose tissue, which leads to a decrease in the capture of antigens.