Required Practicles Paper 1

Question 1

How would you prepare a microscope to look at an onion

Answer 1

-peel one cell thick of the onion and put it on the slide with a drop of water
-add 2 drops of iodine solution to stain the cell so the internal structure become more visible
-place a cover slip on top to flatten the onion

Question 2

How would you test for starch?

Answer 2

-add iodine solution to the food sample
-if there is starch the solution turns from brown to blue/black

Question 3

How would you test for suger

Answer 3

-add Benedict’s solution to a food sample
-place in hot water bath for a few minutes
-if suger is present a brick red colour is formed

Question 4

How would you test for protein?

Answer 4

-add biurets reagent to the food sample
-shake solution to mix
-f protein is present the solution turns from blue to purple

Question 5

How would you test for lipids?

Answer 5

-add ethanol to food sample
-pour equal volumes of this mixture to distilled water
-if lipids are present white is formed on the surface of the mixture