Required Practicals

Question 1

The effect of osmosis on plant tissue method.

Answer 1

1. 6 boiling tubes filled with water with varying levels of sucrose in it.
2. Put 6 equal potato cylinders in each tube. Measure the mass of each one.
3. Leave for 40 minutes.
4. Remove them and measure the mass again.
5. Repeat if possible and calculate a mean. The cylinders will decrease or increase in mass if they lose or gain water by osmosis.

Question 2

Microscopy

Answer 2

1. Put a drop of water onto a slide.
2. Separate one of the thin layers of onion- epidermal tissue.
3. Use forceps to put this on the drop of water.
4. Put two drops of iodine on the tissue.
5. Carefully put a cover slip on the slide.
6. Use filter paper to soak up any liquid around the coverslip.
7. Put it on the microscope stage.

Question 3

Microbiology

Answer 3

1. Disinfect your workspace, set up the Bunsen burner, and wash your hands.
   2.Flame the neck of the bacterial culture bottle, collect 1 ml of bacteria with a pipette, then replace the lid and bottle.
   3.Pipette bacteria onto the agar plate and replace the lid. Discard the pipette.
   4.Sterilize a glass spreader with ethanol and flame it, then cool it for 20 seconds.
   5.Spread the bacteria evenly on the plate using the cooled glass spreader.
   6.Place antiseptic-soaked filter paper discs on the plate and secure the lid with tape.
   7.Incubate the plate at 25°C for 48 hours.

Question 4

Effects of temperature on amylase

Answer 4

1. Place one drop of iodine solution into the spotting tile.
2. Set up water baths from ice, body and 50oc+
3. Measure out 5 cm” of starch solution into 4 test tubes.
4. Measure out 1 cm’ of amylase solution into 4 different test tubes.
5. Place one test tube into each water bath.
6. Leave the test tubes in the water baths until the contents of each test tube have reached the temperature of the water baths.
7. make a note of this temperature. Then, carefully pour the amylase solution into the test tube with the starch solution and mix with the glass rod.
8. Remove one drop of the mixed solution on the end of the glass rod and place on the first depression of the spotting tile with the iodine solution. This is ‘time zero. Immediately start the stop clock.
9. Using the glass rod, remove one drop every minute and place onto the iodine solution in the next depression on the spotting tile. Rinse the glass rod with water after each drop.
10. Continue until the iodine solution no longer turns black. This indicates that the starch has been broken down.
11. Record the temperature of the water bath and the time taken for the starch to be broken down in a table.

Question 5

Testing for lipids

Answer 5

1. Grind up some food
2. Transfer it into a small beaker with distilled water.
3. Use a filter on it and put the clear solution in a test tube.
4. Add 3 drops of Sudan II stain. A red-stained oil layer will separate and float to the surface if fat is present.

Question 6

What is used to test for sugars?

Answer 6

Benedict’s solution.

Question 7

What can be used to test for starch?

Answer 7

Iodine.

Question 8

What can be used to test for proteins?

Answer 8

Biuret solution