Osmosis:
Diffusion with water H2O, where the cell is trying to have the same concentration inside and outside, via aquaporins.

Osmolarity:
Solute concentration in a solution

• Water has high solvency.
• Solute: the substance that is being dissolved.
• Solvent: the substance that does the dissolving.
• Solution: the mixture of the solute and the solvent (solvent + solute = solution)

The solution with the higher osmolarity is said to be hyperosmotic to the other.
The solution with lower osmolarity is said to be hypoosmotic.
If two solutions have the same osmolarity, they are said to be isosmotic.

Water Potential (Unit = bars):
If water is going to enter a cell or not, works well with Osmosis\
Ex.
You pour salt on a snail, the water molecules on that snail will stick to the chlorine and sodium ions, and therefore make room for more water, therefore DECREASED the water potential. The lower the more water is being moved.

Pure Water: 0 bars in an open system (no pressure)

Solute Potential:
How much the solutes/salt are opening up space for more water, through osmosis
The more solutes/salt the lower this number will be.
i = ionization constant (From 1 to 2) (1.0 for sucrose AKA no ionization) (2.0 for NaCl)
C = Molar Concentration (moles per Liter)
R = Pressure Constant (R = 0.0831 liter bars/mole K)
T = Temperature in Kelvin

Pressure Potential:
The physical pressure of cells being enlarged with water
Animal Cells would explode from the, but PLANT cells do NOT
This number is then the pressure that the cell walls of the plant cell are exerting on the cell itself.

Tonicity:
The measurement of the relative concentrations of solute in two solutions AKA inside the cell and outside the cell.

Environmental Hypertonicity:
Less solute than water results in Plasmolysis

Environmental Isotonicity:
Equal solute and water result in a Flaccid state

Environmental Hypotonicity:
More solute than water results in a Turgid state AKA the optimum state of a plant.

To show osmosis in action there is this small demonstration:
Below is a plant stem cut into four pieces and then put into different solutions with different concentrations of salt.
The plant stem in the lowest concentration would put suck in more water into its vacuole, because the normal concentration is 0.9% salt for a cell, and the lowest concentration is 0%.
This means that it would contract, whereas the other ones would just become limb and sloppy.