The cell membrane, therefore, has two functions: first, to be a barrier keeping the constituents of the cell in and unwanted substances out and, second, to be a gate allowing transport into the cell of essential nutrients and movement from the cell of waste products.
<em>The cell membrane (plasma membrane) is a thin semi-permeable membrane that surrounds the cytoplasm of a cell. Its function is to protect the integrity of the interior of the cell by allowing certain substances into the cell while keeping other substances out.</em>
PH is how acidic or basic something is. 1-7 is acidic and 7-14 is basic 7 is neutral( i.e water). Acids tend to have higher concentrations of hydrogen ions.