2.1.2 Tests Biological Molecules

Question 1

Test for starch

Answer 1

Iodine test, turns blue-black

Question 2

Test for lipids

Answer 2

Ethanol, mix with sample.
Then add water and mix.
If solution turns milky white then it contains lipids.

Question 3

Test for protein

Answer 3

Biuret test, turns purple

Question 4

Test for non-reducing sugar

Answer 4

Add HCL and boil - acid hydrolysis
Cool solution + add alkali (NaOH) to neutralise
Add Benedict’s solution + head for 5 mins at 80 degrees
Positive test = from blue to green, yellow orange, brick red.