Biology laboratory work: Osmosis observation Measuring the dependence of net mass gain in potato pieces on concentration of sugar solution By Jonas Kulikauskas Siauliai Didzdvaris Gymnasium Hypothesis: The more sugar in solution, the more potato mass will decrease. Aim: To see how potato mass will change at different concentration solution. Research question: How the mass of potato will change at different concentration solutions? Variables: Dependent: solution concentration.

Independent: sugar concentration in potatoes. Controlled: time, potato form. Apparatus: 1. 5 plastic cups 2. Distilated water 3. Potato 4. Knife 5. Clock 6. Electronical scales (±0,05) 7. Bag of sugar 8. Measuring cylinder 9. Tap water Method: Peeling down the potato and cutting it into 1cm3 cubes (25 cubes) Weighing potatoes on the scales Putting different amount of sugar into five plastic cups (1st no sugar 2nd 6,8g 3rd 13,7g 4th 20,5 5th 27,4g) Adding 100ml of water to each of the cups Mixing the sugar with water

Putting in 5 potatoes into each cup Waiting 20 minutes Pulling out the potatoes, drying them up and putting on the scales Writing down new mass. Amount of sugar in solutionSolution concentration %Cup numberMass of five cubes before(±0,05g)Mass of five cubes after (±0,05g) 0g0%15,8g6g 6,8g6,37%25,1g5,2g 13,7g12,05%35,5g5,3g 20,5g17. 01%45,6g5,4g 27,4g21,51%55,5g5,3g Graph: While the concentration is from 0% to 6,37% the net mass gets bigger, later on from 12,05% to 21,51% the net mass gets smaller.

When the concentration is from 0% to 6,37% the net mass change is positive, when from 17. 01% to 21,51% - negative. Conclusion: The potato lost more mass as it was submerged in bigger concentration solutions because the bigger concentration difference is, the osmosis will occurs more intensively. Evaluation: I think that laboratory work went pretty well, I managed to see the differences in potato mass change and make a conclusion of it. Next time I should write down original numbers and not rounded ones to give more accurate results.