What structure protects bacterial cells from environmental stress?

The cell wall is the structure that protects bacterial cells from environmental stress. It provides a rigid layer that maintains the shape of the bacteria and offers protection against osmotic pressure, which can cause the cell to burst in hypotonic environments. The composition of the cell wall, primarily made of peptidoglycan in bacteria, is crucial for maintaining structural integrity. It also acts as a barrier to certain harmful substances and helps prevent the entry of toxins.

The cell membrane does play a role in controlling the movement of substances in and out of the cell, but it does not provide the same level of mechanical protection as the cell wall. The nucleus is not present in bacterial cells, as they are prokaryotic organisms that lack membrane-bound organelles. The cytoplasm is the gel-like substance within the cell, but it does not have a protective role against environmental stresses like the cell wall does. Thus, the cell wall is essential for ensuring the survival of bacteria in various environmental conditions.