Please Help!! Explain why the use of embryonic stem cells is controversial and why they are potentially more useful than adult stem cells. Describe a possible compromise between the two sides of this debate

Why are small quantities of chlorofluorocarbons so harmful to the ozone layer? a. the chlorofluorocarbons act like ultraviolet radiation causing large amount of ozone to be produced. b. the chlorine from the chlorofluorocarbons reacts with free molecules of oxygen causing a stop in ozone production c. free oxygen atoms can replace the chlorine in chlorine monoxide, releasing a free atom of chlorine which can then recombine with an oxygen atom in ozone, destroying more ozone. d. chlorofluorocarbons absorb ultraviolet radiation, preventing the formation of ozone select the best answer from the choices provided

What are the two main phases of a cell cycle

The breakdown of food is accomplished by enzymes. a. physical b. chemical c. mechanical d. none of the above