The answer is negative controls. These are groups where no phenomenon is probable. They ensure that there is no effect when there should be no effect. Where there are only two possible outcomes, e.g. positive or negative, if the treatment group and the negative control both produce a negative result, it can be concluded that the treatment had no effect. If the negative control group and the treatment group both yield a positive result, it can be inferred that a puzzling variable is involved in the occurrence under study, and the positive results are not only due to the treatment. In other examples, outcomes might be measured as lengths, times, percentages, and so forth.
It will rain next. The moist air has lots of gas water. And when the warm gas water meets the cool temperature in the atmosphere, it will become liquid water. And when liquid water becomes more and more, it will form rain.
1. natural selection acts on existing traits because you can not evolve into something you didn't have
2. original structures evolve to accomplish new function in order to survive
Answer:
it mostly controls all activites
Explanation:
the cell is main structural and functional unit of life in an animal body so without an animal cell the body won't function at all
<span>the pelvic colon, rectum, and bladder
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