Question 4

Cell membrane contributes to the protection, communication, and passage of substances into and out of the cell.

The cell membrane is essential for safeguarding the integrity of the cell, facilitating communication with other cells, and regulating the transport of substances across its boundary.

A) Nucleus

The nucleus is primarily responsible for storing genetic material and coordinating cell activities such as growth and reproduction. While it plays a crucial role in cellular function, it does not directly contribute to the protection or transport of substances across the cell boundary.

B) Cell membrane

The cell membrane serves as a protective barrier that maintains the cell's internal environment. It is integral to communication through receptor proteins and allows selective passage of materials in and out of the cell, making it the correct answer.

C) Endoplasmic reticulum

The endoplasmic reticulum (ER) is involved in the synthesis and processing of proteins and lipids. However, it does not directly provide protection or facilitate communication across the cell boundary, which are key aspects highlighted in the question.

D) Cytoplasm

The cytoplasm is the gel-like substance within the cell that holds organelles and is involved in various metabolic processes. While it supports cellular functions, it does not serve the specific protective and communicative roles attributed to the cell membrane.

Conclusion

The cell membrane is the definitive component that provides protection, facilitates communication, and regulates the movement of substances, aligning perfectly with the question's criteria. Other options, while important in their respective roles, do not fulfill all aspects of the question as effectively as the cell membrane.