2.6 Required practical 3

Question 1

What is the theory behind this practical

Answer 1

Producing a dilution series will allow you to plot a calibration curve so you can determine the water potential of potatoes

Question 2

What is the conclusion of this experiment

Answer 2

• Potatoes in solutions with higher water potentials than itself will gain mass
• Water moves in by osmosis from a higher water potential to a lower water potential

Question 3

Describe a method for this practical

Answer 3

1. Make a dilution series of 1M sucrose solution at 0.2, 0.4, 0.6, 0.8 and 1.0M sucrose. Dilute using distilled water.
2. Measure 5cm^3 of each dilution into separate test tubes.
3. Use a cork borer to cut out 6 potato chips and cut down the sections into identically sized chips. Dry each chip using paper towel to remove excess water.
4. Weigh each potato and record the starting mass
5. Place a potato chip in each test tube and leave for 20 minutes.
6. Remove each potato chip, dry gently with a paper towel and weigh the final mass.
7. Calculate the percentage change in mass for each sucrose solution.

Question 4

What is water potential

Answer 4

The tendency of water to diffuse from one area to another.

Question 5

What are the hazards associated with this practical

Answer 5

Scalpel and broken glass.

Question 6

What are the risks of scalpels and broken glass

Answer 6

Cuts from a sharp object.

Question 7

What are the safety precautions for the scalpel

Answer 7

• Cut away from fingers
• Use forceps to hold sample whilst cutting
• Keep away from the edge of the desk

Question 8

What are the precautions for broken glass

Answer 8

• Take care when handling glass objects
• Keep glassware away from edge of desk