The dense, active protoplasm found in the center of the cell is the:

The dense, active protoplasm located in the center of a cell is indeed the nucleus. The nucleus serves as the control center for cellular activities, housing the genetic material (DNA) that dictates the functions and behavior of the cell. This organelle is crucial for cell reproduction and regulatory functions, orchestrating various cellular processes such as growth, metabolism, and the response to external stimuli.

The nucleus is surrounded by a nuclear membrane that protects the DNA and separates it from the cytoplasm, allowing for compartmentalization of cellular processes. This structure is fundamentally important in the life of the cell, as it ensures that the genetic information is preserved and accurately replicated during cell division.

In contrast, the other options refer to different cellular components with distinct roles. The cell wall is a rigid outer layer that provides structural support to plant cells. Mitochondria are known as the powerhouse of the cell, primarily involved in energy production through cellular respiration. Cytoplasm is the jelly-like substance within the cell membrane that contains organelles and is involved in many metabolic reactions, but it is not specifically located in the center of the cell and does not house genetic material like the nucleus does. Thus, understanding the unique functions of each component highlights why the nucleus is the