What must happen before la a chemical reaction can begin

Me the formula cacl2 represents the compound

In a lab, scientists grew several generations of offspring of a plant using the method shown. what conclusion can you make about the offspring? a. they formed from meiosis and mitosis. b. they have half the number of chromosomes as their parent. c. they have low genetic variability among them. d. they will be able to reproduce only after they grow flowers.

Body temperature is tightly regulated in mammals for example when external temperatures drop too much the body of a mammal response by in order to it's core temperature.