Algonquin College Health Program Assessment (AC-HPAT) Practice Exam

What is the main function of the cell membrane?

1. Energy production

2. Regulating entry and exit of substances

3. Protein synthesis

4. DNA storage

The correct answer is: Regulating entry and exit of substances

The main function of the cell membrane is to regulate the entry and exit of substances. This semi-permeable barrier is critical for maintaining the internal environment of the cell, allowing it to control what materials are allowed to enter and exit. Through various mechanisms such as passive transport, facilitated diffusion, and active transport, the cell membrane selectively permits the passage of ions, nutrients, and waste products. This selective permeability ensures that essential substances can enter the cell while keeping harmful substances out, which is vital for the cell's overall homeostasis and function. Although energy production, protein synthesis, and DNA storage are crucial cellular processes, they are not the primary functions of the cell membrane. Energy production occurs in organelles like mitochondria, protein synthesis mainly happens at ribosomes, and DNA storage is confined to the nucleus of eukaryotic cells. Thus, the regulation of material movement across the cell membrane is essential for the survival and proper functioning of the cell.