Potato Osmosis Lab (Notes)

Use the following table for data if you were unable to complete the lab due to absences:

Initial Tonicity of Initial Final Final Change Initial Final Turgidit Solution Length length Change in turgidity Solution in length mass g mass g y (iso-, cm cm mass g (flimsy or cm (day 1) (day2) (flimsy hypo-, or (day1) (day2) crisp) or crisp hypertonic) Distilled 6.6 cm 7.1 cm +0.5 cm 6.3 g 7.4 g +1.1 g Crisp Crisp Water Salt 5 cm 4.5 cm -0.5 cm 7.5 g 5.8 g -1.7 g Crisp Flimsy Solution Sugar 6.5 cm 6.5 cm 0 cm 4.4 g 4.9 g +0.5 g Crisp Crisp Solution

Notes:

 Solvent: Chemical that dissolves other chemicals

 Solute: A chemical dissolved in a solvent

 Solution: The mixture of the solvent and solute(s)

 Osmosis: The movement of water across a membrane from high concentration to low concentration

 Tonicity: The relationship between solute concentrations inside and outside a membrane

o Hypertonic Solutions: Higher solute concentration outside the membrane o Hypotonic Solutions: Lower solute concentration outside the membrane o Isotonic Solutions: Equal concentrations of solute inside and outside the membrane

 Things to remember about potatoes: o A potato is a root . It is very high in sugar content because roots store sugars in the form of starch in their roots . It also has some water because roots store water for plants o A potato is made of plant cells . Plant cells have a cell membrane like animal cells . Plant cells have a cell wall which keeps them structured In the Lab:  We placed a potato in a solution of water o There is a lower concentration of the solute (sugar) outside the potato o This is a hypotonic solution o Water will move from high to low concentration across the cell membranes . There is a higher water concentration outside the potato, so the water will move into the potato

*this is why the potato in the water solution gained weight and length; it also stayed crispy because the cells were full of water and pushing up against the cell walls*

 We placed a potato in a solution of salt o There is a higher concentration of salt outside the potato o This is a hypertonic solution o Water will move from high to low concentration across cell membranes . There is high water concentration inside the potato, so the water will move out of the potato . *this is why the potato in the salt solution lost weight and length; it also became flimsy because the cells were no longer full of water and did not push against the cell walls*

 We placed a potato in a solution of sugar o There is an equal concentration of sugar within and outside the potato o This is an isotonic solution o Water will not stop moving, but an equal amount of water will move into and out of the cells keeping a balance

*this is why the potato in the sugar solution stayed about the same weight and length; it stayed crisp because there is enough water to fill the cells with*

YOU SHOULD NOW BE ABLE TO ANSWER QUESTIONS 1-11 ON THE RESULTS AND CONCLUSIONS PORTION OF THE POTATO OSMOSIS LAB (CHECK MY WEBSITE FOR THE LAB WORKSHEET)