Question

A student tested four unknown solutions of macromolecules with three reagents. She also tested the solubility of the solutions with water, a polar solvent, and hexane, a non-polar solvent. Her results are shown in the table below.

Solution	Benedict's Solution	Biuret Solution	Iodine	Iodine Solubility
1 2 3 4	yes no no no	no no yes no	no yes no no	water water water hexane

Which of these correctly identifies the macromolecule found in each solution?

• A. Solution 1: protein
  Solution 2: starch
  Solution 3: monosaccharide
  Solution 4: lipid
• B. Solution 1: lipid
  Solution 2: protein
  Solution 3: starch
  Solution 4: monosaccharide
• C. Solution 1: monosaccharide
  Solution 2: protein
  Solution 3: lipid
  Solution 4: starch
• D. Solution 1: starch
  Solution 2: monosaccharide
  Solution 3: lipid
  Solution 4: protein
• E. Solution 1:monosaccharide
  Solution 2: starch
  Solution 3: protein
  Solution 4: lipid

Answer 1

The correct option is E Solution 1:monosaccharide

Solution 2: starch
Solution 3: protein
Solution 4: lipid

I. Solution 1 is showing solubility in water and positive test for Benedict's solution. This means that it's a carbohydrate i.e. it could be a monosaccharide.

II. Solution 2 is showing solubility in water and positive test for Iodine. This means it's starch.

III. Solution 3 is showing solubility with water and positive test for Biuret solution. This means it's protein.

IV. Solution 4 is showing solubility in hexane, a non polar solvent and no positive test for any of the reagents. This means it's lipid solution.

So, the correct answer is :

Solution 1: monosaccharide

Solution 2: starch

Solution 3: protein

Solution 4: lipid