Final answer:
The cell membrane is the thin protective layer with tiny openings, known as protein-lined pores, facilitating material exchange for the cell.
Step-by-step explanation:
The thin protective layer around the cell with tiny openings for material exchange is the cell membrane. The cell membrane is akin to the cell's "skin," comprising primarily of lipids, and functions as a selective barrier. It allows particular substances to enter or leave the cell while blocking others, facilitating the exchange of materials between the cell and its environment. small holes known as protein-lined pores present in the membrane play a crucial role in this process. By contrast, the nucleus, ribosome, and the endoplasmic reticulum serve different functions within the cell: the nucleus houses genetic material, ribosomes synthesize proteins, and the endoplasmic reticulum processes and transports proteins and other cellular substances.