a dam is built that separates a river into two sections—a deep upstream section and a shallow downstream section. when the dam is first built, a fish species is able to move from the upstream section into the downstream section, but not vice versa. predators can more easily catch the fish in the shallow downstream section than they can in the deep upstream section. which scenario is most likely to lead to speciation?

thrombocytopenia, which is a deficiency in blood platelets, can cause bleeding and bruising in the dermis similar to senile purpura. other possible causes include: exposure to ultraviolet rays and aging skin are common causes of senile purpura. senile purpura may also be a sign of collagen loss in the skin and bones.

a unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring.