OSMOSIS IN CELLS
Osmosis is the diffusion of water molecules from a dilute solution (high
concentration of water) to a more concentrated solution (low concentration of
water) across a partially permeable membrane
The cell membrane is partially permeable which means it allows small
molecules (like water) through but not larger molecules (like solute molecules)
TONICITY
A solution can be:
HYPERTONIC, when the
solute concentration
outside the cell is higher
than that inside the cell
ISOTONIC, when the
solute concentration
outside the cell is the
same as inside the cell
HYPOTONIC, when the
solute concentration
outside the cell is lower
than that inside the cell.
TURGIDITY IN PLANT CELLS
When water moves into a plant cell, the
vacuole gets bigger, pushing the cell
membrane against the cell wall.
The force of this increases the turgor pressure
within the cell making it firm or turgid.
The cell wall stops too much water from
entering and prevents the cell from breaking.
If plants do not receive enough water the cells
cannot remain turgid and the plant wilts.
Cells that are not turgid are flaccid.
PLASMOLYSIS
When too much water moves out of a plant cell
the vacuole shrinks.
This pulls the cell membrane away from the cell
wall.
In plasmolysed cells, the cell membrane has
pulled away from the cell wall
SOURCES:
CONTACT: HELLO@REALLYGREATSITE.COM
CIE
IGCSE
Biology.
Revision
Notes.
Osmosis.
https://www.savemyexams.co.uk/notes/igcse-biology-cie-new/3-movement-inout-of-cells/3-2-osmosis/
Biology
Notes
for
IGCSE.
Osmosis.
https://biologyigcse.weebly.com/osmosis.html
Khan Academy. Osmosis and Tonicity. https://www.khanacademy.org/science/apbiology/cell-structure-and-function/mechanisms-of-transport-tonicity-andosmoregulation/a/osmosis