(number 19)what is the name given to a process which allows entrance of any substance into a cell ?

19 is exocytosis. It’s a  process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane.

20 is chromosomes. When cells divide, they pass the genetic plan for the entire organism to the new cells. Different parts of this plan are expressed in the different cells. The genetic information is held in molecules called DNA. A cell's DNA is stored in the nucleus in structures called chromosomes.

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.