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Osmosis/homeostasis/cell membrane transport Cheat Sheet by

Study notes on osmosis, homeostasis, the cell membrane and types of transport

Vesicular Transport

- Active transport process
- Vesicles: small spheres a membrane
- Function in movement of material
- Occurs when larger molecules or big clumps of material need to be transp­orted
- Endocy­tosis & Exocytosis

Vesicular Transport- image


Used for large molecules, clumps of food and even whole cells
Used to get rid of wastes or release valuable materials cells have made
ex) releasing hormones like dopamine
Receptor - Mediated Endocy­tosis




simple vs facili­tated diffusion

simple diffusion
facili­tated diffusion
assisted by carrier protiens
occurs through the phosph­olipid bilayer
occurs through the membrane protiens
small and non polar molecules transp­orted
large and polar molecules transp­orted
rate of diffusion is directly propor­tional to the concen­tration gradient and he membrane permea­bility of the solute molecule
rate depends the carrier protein o


In terms of molecules, explain what happens to a sugar cube when it is placed into a beaker of water.
The sugar cube dissolves in the water, the sugar molecules break apart and dissolve in the water which is a solvent and the sugar cube is the solute.


A substance that is dissolved in a solution.
In a solution, the substance in which the solute dissolves.
A mixture that forms when one substance (the solvent) dissolves another (the solute).
Selective permea­bility
A property of a plasma membrane that allows some substances to cross more easily than others.
The ability of a solution to cause a cell to gain or lose water; it depends partly on the concen­tration of non-pe­net­rating solutes relative to the inside of a cell.
What is the relati­onship between rate of diffusion and molecular weight?
Lower molecular weight substances diffuse faster; Higher molecular weight substances diffuse slower.
What does heating water do to the rate of diffusion of tea?
Higher temper­atures increase the rate of diffusion.
What envior­nment do plant cells work best at and why
hypotonic Water is constantly pushed up against the cell. The cell swells, but the cell wall prevents it from bursting.
consum­ption of too much water, over dilutes necessary ions and can cause death, osmore­gul­ation failure

diffusion graphs

Passive vs Active transport

requires energy in the form of ATP
does not require energy
occurs AGAINST the concen­tration gradient
occurs DOWN the concen­tration gradient
from low to high concen­tration
from high to low concen­tration
sodium­-po­tassium pump
facili­tated diffusion

Tonicity and Osmosis

What is tonicity?
Measure of water pressure inside a cell compared to outside the cell.

Tonicity and Osmosis

The concen­tration of the solute outside the cell are LOWER than inside the cell
The concen­tration of the solute outside the cell are EQUAL than inside the cell
The concen­tration of the solute outside the cell are HIGHER than inside the cell
The water moves to the higher solute concen­tration inside the cell
The water has no net movement and nothing happens to the cells.
The water leaves the cell to the higher solute concen­tration
cell swells and can burst
no change
cells shrink
plant cells work best
human cells work best
low osmotic pressure
equal osmotic pressure
high osmotic pressure

Transport and Cell Membrane

What is cell transport?
Cell transport is the movement of substances across the cell membrane
What is the most important feature of the cell’s phosph­olipid membrane?
The phosph­olipid bilayer because it's select­ively permeable.
Why is it important that cell membranes help maintain the homeos­tasis within the cell
So certain things that shouldn't be in our cells can get in and the things we do need can.
What is the function of transport proteins embedded in the cell membrane?
They move larger molecules in and out of the cell because they cant pass through the phosph­olipid bilayer

Real life scenarios

What type of transport is a friend spraying perfume in a room and you not noticing it for a few minutes
Diffusion is used when someone prays perfume, the molecules with the scent in them will spread out across the room more and more.
If the amoeba was placed in salt water the amoeba will shrink because the solute concen­tration in the salywater is greater than in the amoeba so the water in the amoeba moves out to the salt water making the amoeba shrink.
I think they would use phagoc­ytosis because phagoc­ytosis is taking in a large molecule that will eventually digest inside the cell. Or they use endocy­tosis because endocy­tosis is take in molecules.
Explain the difference between osmosis and diffusion
in diffusion all particles move freely down concen­tration gradients. In osmosis only water (solvent) molecules move across a partially permeable membrane from a dilute solution to a concen­trated solution.


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