The part of a expirement that is not being tested and is used for comparison

Which of the following is true of microbes? a. ninety-nine percent of all microbes are pathogenic.b. gene expression in bacteria is very similar to gene expression in humans, which facilitates the use of bacteria in recombinant biotechnology and gene therapy.c. all bacterial enzymes are harmful to humans and the environment.d. microbes create pollutants and toxins that harm the environment.

For a comparative or experimental investigation, scientists often make a testable about a scientific question, and then they test it in the investigation. a.control b.hypothesis c.procedure d.system

The cluster of developing cells from conception until birth is called an