Question

1) A portion of a biological sample turns a pink-purple color after Biuret Reagent is added. What biological chemical is present in the sample?

a. Protein

b. Lipid

c. Reducing Sugar

2.Why would you suspect that starch does not easily dissolve in water at room temperature?

a. Starch is too hydrophilic to easily go into solution.

b.  Starch is too large to easily go into solution.

c.Starch is too hydrophobic to easily go into solution.

Answer 1

Protein is present in the sample.

Explanation: biuret reagent is mainy used to detect the present of proteins in the given sample.This reagent is used in protein estimation where copper present in reagent reacts with the peptide bonds made up of amino and carboxy group where it attaches to amino group that is to nitrogen atom and turns the colour from.blue to purple .

Starch is too large to go easily to solution.

Explanation: where starch is not soluable in water at room temperature it is soulable in hot water because the starch contains larger macromolecules like amylopectin which is present in crystalline form so cannot dissolve in water in room temperature if increase of temperature it can be soluable.