The scientist asks a new question because the results of the first investigation lead to new scientific questions that need to be tested. After asking a new question (a question that is based on observations and that is testable) the scientist will form a hypothesis that needs to be tested.
True, the plasma membrane is selectively permeable and controls the various substances that are allowed into the cell and that are allowed to leave the cell.
You may have to enlarge it but here you go!
