RP3 Osmosis

Question 1

what is osmosis?

Answer 1

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

Question 2

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

Answer 2

• cut identical potato cyclinders 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 towels
• record length and mass of each cylinder
• draw graph of change in mass in grams (y axis) against concentration of solution in mol dm^-3 (x axis)

Question 3

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

Answer 3

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

Question 4

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

Answer 4

each cyliner may have a different amount of water on its surface, so masses may vary. blotting cylinders allows masses to be comparable

Question 5

what safety precautions should be taken with this experiment?

Answer 5

handle cork borer and scalpel with care