Osmosis and Diffusion: OnRamps Bio

Osmosis

net movement of water

stronger concentration gradient

faster rate of diffusion

What happens in Osmosis?

force of diffusion will move water molecules toward an area of high solute concentrations.

Osmotic pressure

tendency for water to move towards areas of greater solute concentration

hypertonic, hypotonic, isotonic

solutions outside of the cell

hypertonic

higher solute concentration to the cell and will shrink as osmotic pressure drives water out of the cell

hypotonic

lower solute concentration to the cell and will swell as the osmotic pressure drives water into the cell

isotonic

same solute concentration to the cell and stays the same size since there is little to no osmotic pressure

turgor pressure

pressure generated by this water against the cell wall

turgor pressure (in isotonic or hypertonic solution)

decreases and causes wilting in the plant structure

plasmolysis

In hypertonic solutions, when a plant cell’s plasma membrane shrinks away from the cell wall

Change in mass (g)

post-treatment mass (g) - pre-treatment mass (g)

Percent change in mass

[change in mass (g) / original mass (g)] * 100

Independent Variable

concentration of salt water

Dependent Variable

percent change in mass

Negative Percent Change in Mass (-)

post-mass less than pre-mass