AP Biology - Diffusion & Osmosis

Simple passive diffusion

Molecules normally move from areas of high to low concentration; does not require input of chemical energy

Active diffusion

Goes against the gradient of low concentration to high concentration; requires a carrier protein and energy

Selective permeability

A property of a plasma membrane that allows some substances to cross more easily than others

Osmosis

Diffusion of water through a selectively permeable membrane

Tonicity

The ability of a solution surrounding a cell to cause that cell to gain or lose water; relationship between concentrations of solute on either side of a membrane

Hypotonic

Having a lower concentration of solute than another solution

Hypertonic

Having a higher concentration of solute than another solution

Isotonic

Having the same solute concentration as another solution

Cytolysis

The bursting of a cell

Turgor pressure

The pressure that water molecules exert against the cell wall

Plasmolysis

Collapse of a plant cell’s cytoplasm due to a lack of water

Dialysis

Movement of a solute through a selectively permeable membrane

Solution that egg was submerged in

Independent variable of egg lab

Percent change in the mass of the egg

Dependent variable of egg lab

Environment, vinegar, time in each solution

Fixed variables of egg lab

Osmoregulation

Regulation of solute concentrations and water balance by a cell or organism

Solute potential

A component of water potential that is proportional to the number of dissolved solute molecules in a solution and measures the effect of solutes on the direction of water movement; also called osmotic potential, it can be either zero or negative.

Pressure potential

This measurement has a minimum value of 0 (when the solution is open to the environment); it increases as pressure increases

Benedict's test

Test for glucose

Iodine, water

Diffusion lab: Which substance(s) entered the bag?

Glucose, water

Diffusion lab: Which substance(s) exited the bag?

Water, iodine, glucose, membrane pores, starch

Rank the size of the molecules from smallest to biggest: glucose, water, iodine, membrane pores, and starch