How can indicators be used to test for the presence of different organic molecules?
Many different test can be performed to detect whether or not organic molecules are present.
A common high school / college biology lab involves testing food samples to determine which organic molecules they contain.
I've included videos which show positive and negative controls for four of these tests. The positive control contains a solution of the molecule being tested for, the negative control is pure water.
Iodine is used to test for the presence of starch:
Benedict's reagent is used to test for simple sugars:
Biuret's reagent is used to test for protein:
Paper Test for Lipids:
I hope this is helpful!