L1 Diffusion and Osmosis

%%Diffusion%% %%is the random movement of molecules from an area of higher concentration of those molecules to a lower concentration.%% If H2S was released into a room, it would spread throughout the room fast as it is a higher concentration than air. Eventually, a dynamic equilibrium will be reached and there will be no net movement from one area to another.

%%Osmosis%% %%is a special case of diffusion. It is the diffusion of water through a selectively permeable membrane (a membrane that allows for diffusion of certain solutes and water) from a region of higher water potential to a region of lower water potential.%% Water potential is the measure of free energy of water in a solution.

%%Active transport%% %%uses energy from ATP to move substances through the cell membrane, usually moving substances against a concentration gradient from low to high.%%

Dialysis is the movement of a solute through a selectively permeable membrane.

Exercise 1A

Glucose and starch solution is poured into dialysis bag. That bag is placed into a beaker with iodine in it. Iodine is amber before. Dialysis bag is clear.

After, the bag becomes bluish black, indicating iodine diffused into the bag from the water. Starch did not diffuse into the outer water, leaving the outer water amber.

Glucose was tested (through Benedict’s test) in the outer beaker water and was found. It was also still in the dialysis tube.

The bag is semipermeable, or selectively permeable.

Exercise 1B

Isotonic: When two solutions have the same concentration of solutes, they are isotonic to each other.

Hypertonic: solution with more solute

Hypotonic: solution with less solute

^Only used to compare solutions

Exercise 1C

Water will always move from an area of higher water potential (higher free energy, more water molecules) to an area of lower water potential (lower free energy, fewer water molecules).

%%Water concentration and solute concentration are inversely related.%%

Solute potential is the effect that solutes have on a solution’s overall water potential.

Less water potential = more sugar

water mobility

Exercise 1D

Exercise 1E

Plasmolysis is the shrinking of the cytoplasm of a plant cell in response to diffusion of water out of the cell and into a hypertonic solution surrounding the cell.