Biochemical tests Flashcards
Which biochemical test is used to test for reducing sugars?
Benedict’s test
Why is sucrose known as a non-reducing sugar?
It does not reduce copper sulfate
What is a positive result for the Benedict’s test?
Solution turns brick-red when heated
What do you need to do to non-reducing sugars such as sucrose before testing with Benedict’s reagent?
Hydrolyse it into its constituent monosaccharides
Which test is used to test for starch?
Iodine test
What is a positive result when testing for starch with iodine or potassium iodide?
Turns blue/black
Which colour is seen with Benedict’s test when there is trace amount of reducing sugar?
Green
What colour is seen with the Benedict’s test when there is no reducing sugar?
Blue
Which colour is seen with the Benedict’s test when there is a moderate amount of reducing sugar?
Orange
Which colour is seen with the Benedict’s test when there is a large amount of reducing sugar?
Brick-red
Which colour is seen with the Benedict’s test when there is a large amount of non-reducing sugar?
Blue
Which technique could be used to separate a mixture of monosaccharides to identify their compounds?
Chromatography
Reduction is a chemical reaction involving the… (electrons)
Gain of electrons or hydrogen
What do reducing sugars donate to Benedict’s reagent?
Electrons
What is the insoluble red precipitate formed when a reducing sugar is heated with Benedict’s reagent?
Copper (I) oxide
