Biological Molecules Stuff

Question 1

How to test for non-reducing sugars?

Answer 1

Boil sample with HCl and then neutralise this with sodium hydrogencarbonate. Then add Benedict’s solution and heat in water bath. Positive result is colour change from blue to orange/red

Question 2

Test for starch

Answer 2

Add a few drops of brown iodide. Positive test will be blue-black

Question 3

How to test for proteins?

Answer 3

Biuret test: add equal amounts of sodium hydroxide to sample at room temp. Then add a few drops of copper sulfate solution and mix. Colour change from blue to purple.

Question 4

How to test for amylase?

Answer 4

Do biuret test (to test for da enzyme) and should turn purple. Then add starch, and then test for reducing sugar using Benedict’s test (to test for da digested starch which is now glucose)