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.
Bacteria can convert nitrogen in the air into a form plants can use
Answer:
The plants in an ecosystem produce food for most of the other organisras that live in that ecosystem. The role of a plant in its ecosystem is its <em>trophic level</em>
Explanation:
Plants are the least to be found in the trophic level, they are otherwisely called <em>autotrophs. </em>They make food for themselves while others among the trophic level depend on them
The answer to this question is D: Psychoactive. It is the world's most widely consumed psychoactive drug.
Answer:
B.The sperm and egg.
<h3>....Hope it helps you.....</h3>
