Four conditions are needed for natural selection to occur: reproduction, heredity, variation in fitness or organisms, variation in individual characters among members of the population. If they are met, natural selection automatically results.
Natural selection is based on the idea of differential survival and reproduction. Basically this means there are genetic differences between individuals and there are too many individuals in the population to survive. The ones with the best genetic variations will survive and pass their genes on to their offspring. This doesn't happen if all organisms in the population are identical - either they all die, or they all survive.
If not my mistaken this would be the answer The cell will change the concentration of water within the cell to match the concentration of water outside the cell.
You have to first make some observations and then ask a question. Then you make a hypothesis (or guess) what the answer is - do the experiment to see if you're right!
