The thing that would mostly make the results of the experiment invalid would be the students themselves. No one is built the same, and the exact same food can have very different effects on different people.
It would have to be the third answer, "a strong thunderstorm destroys many of the nests of a bird population."
Answer:
The development of the brain continues past childhood. For example, if a monkey pushes a lever with its finger several thousand times a day, the Brain tissue that controls the finger changes as a result of the experience.
The scientific method is a problem-solving approach used in Biology and other scientific disciplines. This method has five basic steps which help scientists test their hypotheses. The first step of the scientific method is to make an observation. In this particular example, the scientist observes probably that salt has chemical and physical properties which could affect the life cycle of bacteria. The second step would be to ask a question and that would be to ask whether salt indeed has any effect on that particular type of bacteria that he/she studies. The third step would be to form a hypothesis and that would be to state that the specific bacterial type will be strongly affected by the salt. The fourth step would be to predict that if the scientist exposed this bacterial type to a salty environment, the bacteria would not survive. The fifth and final step is to test this prediction and if the bacteria do not survive, then the scientist can conclude that salt affects this bacterial type.
