Final answer:
The plasma membrane of a cell determines what can enter and leave the cell. Small, non-charged molecules can freely pass through, while larger molecules and ions require specific mechanisms. Examples of what goes into a cell are oxygen and glucose, while exocytosis is the process for exporting substances out of the cell.
Step-by-step explanation:
The plasma membrane of a cell determines what can enter and leave the cell. It is a semipermeable membrane, meaning that it allows some substances to pass through while restricting others. Small, non-charged molecules like oxygen, carbon dioxide, and water can freely pass through the membrane. Larger molecules and charged ions, on the other hand, require specific mechanisms such as protein channels or active transport to enter or leave the cell.
Some examples of what goes into a cell are oxygen and glucose, both of which are reactants for cellular respiration. Oxygen enters the body through breathing, while glucose enters the body through eating.
For substances that need to be exported out of the cell, exocytosis is the process used. This involves the cell packaging the substances into membrane-bound vesicles, which then fuse with the cell membrane to release their contents into the extracellular fluid.