Michigan Test for Teacher Certification (MTTC) Secondary Integrated Science Practice test

Which cellular component acts as a protective barrier and is involved in cell communication?

1. Cell Wall

2. Nucleus

3. Cell Membrane

4. Pili

The correct answer is: Cell Membrane

The cell membrane, also known as the plasma membrane, serves as a protective barrier that surrounds the cell, maintaining its integrity and regulating the movement of substances in and out. This selective permeability is crucial for maintaining homeostasis within the cell. Additionally, the cell membrane is embedded with various proteins that play key roles in cell communication. These proteins can act as receptors that bind to signaling molecules, facilitating communication between the cell and its environment as well as between different cells. While the cell wall provides protection and structural support primarily in plant cells, it does not play a direct role in cell communication. The nucleus is the control center of the cell, housing genetic material, but is not involved in communication at the cellular level. Pili are hair-like structures found on the surface of some bacterial cells that aid in attachment to surfaces and the exchange of genetic material, but they do not serve as a protective barrier in the same way the cell membrane does. Thus, the cell membrane is essential for both protecting the cell and facilitating communication processes.