Question

Exercise C: Application of the chemical tests to identify biological molecule digestion efficiency Practice with experimental predictions - carbohydrate digestion 1. Complete starch digestion Dolore a. If ALL starch molecules are completely digested (as shown on the right), then what molecules would be left in the solution at the end? b. If ALL starch molecules are completely digested, what would be the experimental result following a Benedict's assay? c. If ALL starch molecules are completely digested, what would be the experimental result following an lodine assay? 2. No starch digestion a. If NONE of the starch molecules are completely digested (as shown on the right), then what molecules would be left in the solution at the end? b. If NO starch molecules are completely digested, what would be the experimental result following a Benedict's assay? c. If NO starch molecules are completely digested, what would be the experimental result following an lodine assay?

Answer 1

Starch is produced in plant as food. Starch is made up of two subunits

Amylose -- linear molecule of glucose polymer, contains 1-- 4 bond

Amylopectin -- branched molecule, made up if glucose, has 1-- 4 abs 1---6 bond.

1) upon complete hydrolysis of starch, it will release glucose

a) release glucose in solution upon complete hydrolysis

b) this solution will give positive Benedict test

Benedict test is done to detect presence of reducing sugar in solution.

Sugars which has free functional group at numeric carbon are reducing sugar.

c) iodine test will be negative

As iodine test is done for presence of polysaccharide. So Strach here is completely digested in to glucose so this test will be negative.

2)

a)in case of no digestion starch molecules will be present in solution

b) negative Benedict test

c) positive iodine test .

3) in case of partial digestion

a) both glucose and starch will be present

b) positive Benedict test

c) positive iodine test