Answer:
The role of cell membranes is crucial in the process of expelling toxic or metabolic waste.
Substances are is inserted or deleted into the membrane through a number of mechanisms :
1) Exocytosis: This refers to the expulsion of unwanted metabolic waste throughout the cell membrane.
2) Endocytosis, on the other hand, is the process (at a cellular level) via which food/medicine and various substances are brought into the cell. It is a form of active transport.
Both Exocytosis and Endocytosis always execute through the cell membrane. Therefore, the cell membrane is critical to the excretions of materials from the body and cell.
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