Approximately how many millions of years did each ERA last?

What does polymerase chain reaction (pcr) do? o a. separates dna fragments by size o b. cuts a dna sample into fragments o c. provides an overall picture of a person's chromosomes o d. makes more copies of a sample of dna

Consider the following planned experiment. factor experimental group control group light exposure tots of sun tots of sun amount of water weekly weekly type of soil nutrient rich nutrient rich size of pot large which variable is being tested in this experiment? small a. size of pot b. type of soil c. light exposure d. amount of water

How do you suppose living conditions differ between the country furthest along in the demographic transition compared to the country earliest in the transition? how would living conditions in these two countries affect both birth and death rates?