Cambridge O Level Biology · Syllabus 5090 · Cells
Cellulose cell wall
What is Cellulose cell wall?
A rigid layer made of cellulose that lies outside the cell membrane of a plant cell. It supports the cell, resists bursting when water enters by osmosis, and helps the cell keep its shape. It is fully permeable, so it does not control which substances enter or leave; that is the job of the cell membrane inside it.
This definition is part of the Cells chapter in Cambridge O Level Biology.
Cellulose cell wall in context
Animal, plant and bacterial cells all share a cell membrane, cytoplasm and ribosomes, but they differ in what else they contain. An animal cell also has a nucleus and mitochondria. A plant cell adds a cellulose cell wall, a permanent sap vacuole and, in its photosynthetic cells only, chloroplasts. A bacterial cell has a cell wall that is not made of cellulose, circular DNA lying free in the cytoplasm and sometimes plasmids, but no nucleus, no mitochondria and no chloroplasts. In every cell the membrane controls what enters and leaves; a cell wall only supports, because it is fully permeable.