Potato Osmosis Lab Quiz

aqueous solution

water that contains dissolved substances

membrane permeability

membranes are selectively permeable which means that they allow water to pass through freely while controlling other solutes

fueling cells

cells need sugar and oxygen to function, make fuel, repair themselves, duplicate etc. Cells also need this fuel to get rid of waste. If it doesn't get rid of waster, the cells are going to poison themselves and die.

active transport

the movement of materials through a cell membrane using ATP

passive transport

the movement of substances across a cell membrane without the use of ATP. substances can diffuse through the membrane as long as they are permeable. Diffusion uses kinetic energy.

dialysis

Breaks down big molecules like starch proteins and some charged ions as they cannot pass through the membrane. By breaking it down it allows small particles of molecule to seep into the membrane.

Osmosis

Diffusion of water through a selectively permeable membrane. Often water in a solution will separate itself from the solute as water can easily diffuse through the membrane

Hypertonic

Having a higher concentration of solute that cannot cross the membrane

Hypotonic

Having a lower concentration of solute that cannot cross a membrane

isotonic

concentration is at equilibrium

water potential

describes the tendency of water from moving from one place to another, specifically in and out of cells. The higher the concentration of water molecules, the higher the water potential

water potential and osmosis

water tends to flow from a high area of concentration (high water potential) to an area of low concentration in order to create equilibrium due to osmosis.

negative potential

distilled water will always have the highest water potential as there are no solutes dissolved in it. the second you add any solutes in the mix, the water potential will become negative.

positive potential

physical pressure will actually make the water potential positive as it applies pressure and increases the concentration of a substance.

Molarity

the number of moles of solute per liter of solution

Osmolarity

measure of total concentration of solute particles in one liter

glucose procedure

Day 1: The dialysis tubing was cloudy and the water+lugos solution was amber yellow

Day 2: Dialysis tubing was bigger and it was now dark purple. The water solution was clear

what happened with the tap water in the glucose procedure

water seeped into the dialysis tubing (which had low concentration of water molecules) from the beaker (which had a high concentration of water molecules). The dialysis tubing also got bigger.

what happened to glucose in the glucose procedure

glucose diffused out of the bag. it created equilibrium in and out of the bag. particles were small enough to diffuse.

what happened to starch in the glucose procedure

starch remained in the bag as the molecules were too large to diffuse through the dialysis bag.

what happened to lugos (I3K) in the glucose procedure

Lugols diffused into the bag which is why the water no longer had an amber color and why the starch turned purple. its particles were small enough to diffuse.

why do animals blood transport glucose

Because glucose is a much smaller molecule, this allows it to cross the membrane much easier while starch cannot penetrate the membrane on its own.

potato lab experiment

plant cells are surrounded by a cellular membrane and a nonliving cellulose wall. when placing the potato in water, osmosis will occur until the resistance point of the membrane allows no more water molecules to cross. at resistance point, pressure and solute potential are at equilibrium

potato procedure

Day 1: potato strips of the same size are put into beakers with different molarity and concentration of solutes (sucrose).

Day 2: potatoes that got flimsy were placed in the beaker with the higher sucrose concentration. this is because sucrose in this case is hypertonic, so water left the potato cells to the sucrose solution. potatoes that were firm were placed in beakers with low sucrose concentration. this is because sucrose in this case is hypotonic, so water moves into the potato cells

why would leaving potato out in the open affect the experiment

if potatoes had been left out in the open, they would've dried out and changed osmolarity. This would also create a negative potential as water is leaving by dehydration

membrane permeability in potato lab

hypertonic: more solute, decreased mass of potato

hypotonic: less solute, increased mass of potato

isotonic: equal, no change in mass of potato

external effects on potato

temperature and pressure can have an effect on water potential.

salt soil effect on plants

plants would have an even higher concentration of solutes in their cells, all while allowing water to move around it.

what happens at a plant's leaf when water gets pulled up?

transpiration. the water potential in the leaf has to be lower than the one in the root for it to be able to pull up

why don't plant cells lyse when placed in hypotonic solution

Lysing means to break a big molecule into smaller molecules. In plant cells, they have a cell wall that can exert pressure to stop water from continuosly flowing in, impeding the water from lysing the cells

where do plant store water

central vacuole

direction of flow of water

water will always flow into the more negative water potential as it has more solutes. ie: -6.25 is lower than -3.2 so the water will flow towards -6.25

water potential equation

Ψ = Ψs + Ψp

Ψp = pressure potential

bars given. the pressure potential for this lab was 0.

Ψs = solute potential

-iCRT: ionization (how many times a molecule can be split up), molar concentration (amount of moles), pressure constant (0.0831), temperature in kelvin (273 +/- celsius)

line of best fit

A line that is very close to most of the data points in a scatter plot