Question

In a lab situation, a student is asked to identify which macromolecule is found in 3 different solutions.
Solution 1 contains a macromolecule that is composed of atoms of carbon, hydrogen, oxygen and nitrogen. It tests positive with Biuret solution.
Solution 2 contains a macromolecule composed of carbon, hydrogen and oxygen in a 1:2:1 ratio. It tests positive with iodine-potassium iodide solution.
Solution 3 contains a macromolecule that is composed of atoms of carbon, hydrogen, oxygen, and phosphorus.
Which of these best identifies the macromolecule found in each solution?

• A. Solution 1: carbohydrate
  Solution 2: lipid
  Solution 3: protein
• B. Solution 1: carbohydrate
  Solution 2: protein
  Solution 3: lipid
• C. Solution 1: protein
  Solution 2: carbohydrate
  Solution 3: nucleic acid
• D. Solution 1: nucleic acid
  Solution 2: lipid
  Solution 3: protein
• E. Solution 1: carbohydrate
  Solution 2: lipid
  Solution 3: nucleic acid

Answer 1

The correct option is C Solution 1: protein

Solution 2: carbohydrate
Solution 3: nucleic acid

I. The macromolecule that is composed of atoms of carbon, hydrogen, oxygen and nitrogen and tests positive with Biuret solution, shows that it is a protein molecule.

II. The macromolecule that is composed of carbon, hydrogen and oxygen in a 1:2:1 ratio and tests positive with iodine potassium iodide solution shows that it is a carbohydrate molecule.

III. The macromolecule that is composed of atoms of carbon, hydrogen, oxygen, and phosphorus is a lipid molecule.

So, the correct answer is:

Solution 1: Carbohydrate

Solution 2: Lipid

Solution 3: Protein