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PEAZIT Aha card

Cells: a boundary that controls exchange

The membrane separates the cell interior and regulates exchange; a wall adds support.

A simplified comparison of typical plant and animal cells.

Structure	Plant	Animal
Membrane	Yes	Yes
Cell wall	Yes	No

One worked example

An animal cell has a membrane.Without a wall, the cell still has a regulated boundary.
A plant cell has both a membrane and a wall.The wall does not replace the membrane.

Watch out: This is an introduction, not a complete description of every cell. A membrane is neither impermeable nor a conscious guard.

Goal, prerequisites and card origin

What you will learn: Distinguish a cell membrane from a cell wall.

What you need first: The cell is the basic unit of living organisms.

An original PEAZIT working card. Independent expert review and effectiveness testing have not yet taken place. · v1

Show connections

Diffusion: motion and concentration differences

Random particle motion — particles move in both directions — Net flow down the gradient

Concentration difference — more particles cross from the more concentrated region — Net flow down the gradient

Net flow down the gradient — gradually reduces the difference — More even distribution

More even distribution — motion continues at equilibrium — Random particle motion

The membrane separates the cell interior and regulates exchange; a wall adds support.

Without JavaScript, write your answer elsewhere before opening the solution.What do typical plant and animal cells both have: a membrane or a wall? Enter one name.

Solution — open after your own attempt

Cell membrane. Both types have a membrane; animal cells do not have a cell wall.

A question for your next return: A plant cell already has a wall. Does it also need a membrane? Answer yes or no.

Solution — open after your own attempt

Yes. Structural support from the wall does not replace the membrane’s boundary and exchange functions.

Catalogue

Book

WikibooksEN

A-level Biology/Biology Foundation/cell membranes and transport

Link to the page “A-level Biology/Biology Foundation/cell membranes and transport” in Wikibooks. Subject assignment uses its title and source categories.

Biology