What part of the cell acts as the control center?

The nucleus is referred to as the control center of the cell because it houses the cell's genetic material (DNA) and is responsible for regulating cellular activities. This includes controlling gene expression, which determines the production of proteins essential for the cell's structure and function. The nucleus orchestrates the processes of cell growth, metabolism, and reproduction by directing the synthesis of RNA and proteins, essentially managing the entire lifecycle of the cell.

In contrast, the other components mentioned play different roles. The cell membrane functions as a protective barrier that regulates what enters and exits the cell. The cytoplasm is the jelly-like substance that fills the cell and contains organelles, serving primarily as the site for cellular processes and reactions. Protoplasm, which refers to the living part of a cell (including the nucleus and cytoplasm), is a broader term and does not specifically denote the control functions. Thus, the nucleus is distinctly recognized for its controlling role within the cell.