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

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

Answer 2

● 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 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 length and mass can be compared easily

Question 4

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

Answer 4

Each cylinder 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