biology-osmosis required practical

what is osmosis?

the movement of water from a higher water potential to a lower water potential through a partially permeable membrane

describe how you would carry out an investigation into osmosis using potato tissue

• cut identical potato cylinders using a cork borer

• measure and record the length and mass of cylinders using ruler and balance

• add each cylinder to one of three solutions: 1m sugar solution, 0.5m sugar solution and distilled water

• leave cylinders in tubes overnight

• remove cylinders from tubes and blot them using paper towe;s

• record length and mass of each cylinder

• draw graph of change in mass in grams against concentration of solution in mol dm-3

why is it necessary to use a cork borer to cut the cylinders

results in equal sized samples so changes in length and mass can be compared easily

why is it necessary to blot the cylinders with paper after removing them

each cylinder may have a different amount of water on its surface, so masses may vary

blotting cylinders allows masses to be comparable

what safety precautions should be taken with this experiment

handle cork borer and scalpel with care