Required Practicals Flashcards
When testing for protein, what chemical(s) are needed?
Sodium hydroxide and copper sulphate
When testing for lipids, what chemical(s) are needed?
Ethanol
When testing for starch, what chemical(s) are needed?
Iodine
When testing for sugar, what chemical(s) are needed?
Benedicts reagent
What colour will the solution turn if protein is present/not present?
Light blue = no protein present
Lilac = protein present
What colour will the solution turn if lipids are present/not present?
No change = no lipids
Cloudy white = lipids present
What colour will the solution turn if starch is present/not present?
Orange-brown = no starch present Blue-black = starch present
What colour will the solution turn if sugar is present/not present?
Light blue = no sugar present
Brick red / orange / yellow = sugar present
What is special about the test for sugar that isn’t part of the other food tests?
You have to leave it in a hot water bath for three minutes.
Is starch a complex or simple carbohydrate?
Complex
Is sugar a complex or simple carbohydrate?
Simple
In an investigation into the rate of photosynthesis in pondweed, what chemical should be used?
Sodium hydrogen carbonate
In an investigation into the rate of photosynthesis in pondweed, how long should the pond weed be left for?
5 minutes
In an investigation into how pH levels affect enzymes, what three substances need to be added?
pH buffer, amylase and starch.
Describe roughly how to perform an investigation into how pH levels affect enzymes.
Mix substances
Start stopwatch
Remove droplets every ten seconds and place into the iodine in spaces on the spotting tiles.
Stop the stopwatch when a drop is added and the iodine remains orange.
