Movement of Substances ...

Substances have to pass through the cell membrane in order to enter or leave it. Oxygen and nutrients have to enter the cell and carbon dioxide and other waste products need to leave the cell.

If this transport does not occur, the cell would run out of oxygen and nutrients and waste products would build up in the intracellular fluid.

In the case of the amoeba, the exchange of substances occurs directly with the intracellular fluid.

activity

Watch the animation below and notice the substances which pass into the cell. Chemical changes then occur within the cell. Some products become part of the cell. Others are wastes which pass out of the cell.