Solutions
Solute – The substance that dissolves to form a solution eg salt
Solvent – The substance in which a solute dissolves eg water
Solution – A mixture of one or more solutes dissolved in a
solvent eg sea water
Solute
Solvent
DIFFUSION & OSMOSIS
DIFFUSION
•
Diffusion animation
Diffusion is the net movement of particles from a region of
higher concentration to a region of relatively lower
concentration. No input of energy is required.
DIFFUSION & OSMOSIS
OSMOSIS
• Osmosis animation
Osmosis is the net movement of a
solvent, usually water, across a
differentially permeable membrane.
The net movement of water occurs
from the side of the membrane
where there is a weak solution (high
water concentration, low solute
concentration) to the side of the
membrane where there is a strong
solution(low water concentration,
high solute concentration).
Osmosis does not require energy
input.
Osmosis
Amoeba are small unicellular organisms
with a large SA:V
Amoeba in action 1
Amoeba in action 2
Some substances can diffuse into /out of these cells very efficiently
as a result of the large SA: V ratio
Larger food particles can be engulfed: phagoctosis
Plasma Membranes
Functions of the cell
membrane include:
1. It gives a definite shape to
the cell.
2. It contains and provides
protection to the internal
contents of the cell.
3. It is selectively permeable.
4. It can take in solid and liquid
materials by in folding.
5. In animal cells, it is involved
in the formation of vesicles,
cilia, flagella, microvilli, etc.
Plasma Membrane overview 5 min
Passive diffusion across a membrane
Openings
both sides eg
channels for
ion transfer
Attach to carbohydrates
act as antigens
Link cells
together
Binds hormones and
other substances
Fluid Mosaic model of plasma membranes
Web page including good animation
Cell-Membrane-Function
Plasmolysis
Hemolysis & Crenation
Passive v Facillitated Diffusion
Cytosis
Mitosis