What is the jellylike substance that fills the interior of a cell called?

The jellylike substance that fills the interior of a cell is called cytoplasm. It is a vital component of the cell, providing a medium in which the cell's organelles are suspended and where many cellular processes occur. Cytoplasm contains water, salts, and various organic molecules, creating an environment that supports biochemical reactions and helps maintain the cell's shape.

The nucleus, while an essential organelle that houses the cell's genetic material, is not the substance filling the interior; instead, it floats within the cytoplasm. The cell wall is a rigid outer layer found in plant cells and some bacteria, providing structural support, but it does not refer to the internal substance of the cell. Chloroplasts are organelles found in plant cells that are involved in photosynthesis, but they are not the jellylike substance filling the cell. Hence, cytoplasm is the correct term for the medium that fills the interior of a cell.