Which evolved first: viruses or living organisms?

The friction red blood cells encounter when moving past each other. cardiac output: the amount of friction blood encounters during flow through blood vessels. blood pressure: the force of the blood against the vessel wall. blood viscosity: the volume of blood pumped out by one ventricle each minute.

Ablastocyst is a group of cells that forms after a human egg is fertilized. the blastocyst consists of two types of cells. some of these cells will become the placenta. what do the other cells develop into?

Which of the following is an advantage of using embryonic stem cells in medical research? a. the use of embryonic stem cells is much less expensive than the use of adult stem cells. o b. no living tissue is damaged when scientists use embryonic stem cells. o c. embryonic stem cells are able to differentiate into a wider range of cells than adult stem cells. d. there is no controversy surrounding the use of embryonic stem cells.