Which contains all of the living substances of the cell?

• A. Nucleus
• B. Cytoplasm
• C. Cell Membrane
• D. Ribosome

Answer: (B)

Inside a cell, the living material and the machinery that carry out life processes are located in the cytoplasm. This region, bounded by the cell membrane and outside the nucleus, contains the fluid cytosol and many organelles such as mitochondria, ribosomes, and the endoplasmic reticulum. These components work together to generate energy, synthesize proteins, and perform other metabolic tasks that keep the cell alive. The nucleus is a separate compartment that stores genetic material and directs cellular activities, but it is not where the overall metabolic machinery resides. A ribosome is essential, yet it is only one part of the cytoplasmic machinery rather than the whole living content of the cell. The cell membrane defines the boundary but does not itself house the living processes.