Which term refers to the living matter within a cell?

The term that refers to the living matter within a cell is protoplasm. Protoplasm is the gel-like substance within the cell membrane that encompasses all the cellular contents, including the cytoplasm and the nucleoplasm. It is where essential biochemical processes occur, and encompasses the organelles and the genetic material, making it crucial for the cell's life and functions.

In cellular biology, understanding protoplasm is significant because it provides insight into how cells operate as units of life. Distinguishing it from plasma, a component found in blood that is not a cellular structure, shows the importance of clarity in terminology. The terms prokaryote and eukaryote refer to the classifications of cells themselves, rather than the substance within them. Prokaryotes are unicellular organisms lacking a nucleus, while eukaryotes have a defined nucleus and organelles. Thus, while those terms are important in understanding types of cells, they do not describe the living matter within a single cell, which is protoplasm.