20.4 21.3 are the correct answers
Snow falling on glacier would be an example of atmosphere-cryosphere interaction.
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.
Answer:
b. behavioral isolation
Explanation:
It is a type of reproductive barrier that can lead to speciation. Behavioral behavior, such as mating rituals as in when two populations of the same species show some difference in behavior, typically in mating rituals
and signals.
