The firm outer layer

The idea

The cell wall, an extra outer layer of plant cells, provides rigidity and strength, so plant cells are compactly arranged and firm in structure.

Neat and firm

Onion peel cells are closely packed, nearly rectangular and firm. Plant cells have an extra outer layer around the cell membrane: the cell wall.

If a plant cell had no cell wall, what do you think would happen when it is pushed?

• It would stay just as firm
• It would be squashed more easily
• It would not change at all

Wall ON, wall OFF

Push the same cell down with the wall on. Then take the wall off and push again.

Rigidity and strength

The cell wall is an extra outer layer of plant cells. It gives rigidity and strength, so plant cells are compactly arranged and firm in structure.

Onion peel cells have a cell wall. That is why they sit tightly packed, with no space between them.

Notes

The cell wall, an extra outer layer of plant cells, gives rigidity and strength, so plant cells are compactly arranged and firm.

Check yourself

What does the cell wall give to a plant cell?

Which of these cells has an extra outer cell wall?

Where is the cell wall?

• Rigidity and strength — correct. Yes. The wall makes plant cells firm.
• The power to regulate the cell's activities. That is the job of the nucleus.
• A way to let waste out. The cell membrane lets materials in and waste out. The wall gives firmness.
• An onion peel cell — correct. Yes. Plant cells like onion peel cells have a cell wall.
• A muscle cell in the food pipe. Animal cells like this do not have a cell wall.
• A nerve cell. Animal cells like this do not have a cell wall.
• Outside the cell membrane, as the extra outer layer — correct. Yes. It is the extra outer layer of plant cells.
• Inside the nucleus. The nucleus is inside the cell. The wall is on the outside.
• Between the nucleus and the cytoplasm. The cytoplasm is the filling inside the membrane. The wall is outside it.