Question 7

The plasma membrane regulates the transport of substances in and out of the cell.

The plasma membrane serves as a selective barrier that controls the movement of ions, nutrients, and waste products into and out of the cell, ensuring homeostasis.

A) Cell membrane

The term "cell membrane" is often used interchangeably with "plasma membrane," but in a strict sense, it can refer to all membranes surrounding cellular structures. While it is partially correct, the term "plasma membrane" more accurately describes the specific structure responsible for the transport of substances.

B) Cell's cytoplasm

The cell's cytoplasm is the gel-like substance within the cell membrane that houses organelles and various cellular components. It does not function as a regulatory barrier for transport; rather, it is the medium where biochemical processes occur.

C) Nuclear membrane

The nuclear membrane, or nuclear envelope, encloses the nucleus and regulates the exchange of materials between the nucleus and the cytoplasm. However, it is not responsible for the overall transport of substances in and out of the entire cell.

D) Plasma membrane

The plasma membrane is the primary structure responsible for regulating the transport of substances in and out of the cell. It is selectively permeable, allowing certain molecules to pass while blocking others, thus maintaining the internal environment of the cell.

Conclusion

The plasma membrane is the definitive structure that regulates cellular transport, distinguishing it from other components like the cytoplasm or nuclear membrane. While some options may have related functions, they do not fulfill the specific role of transport regulation as effectively as the plasma membrane does. Therefore, it stands out as the correct answer to the question posed.