Both starch and cellulose are made by stringing together many glucose molecules, but starch is easily digested by humans, while cellulose is indigestible. The starch polysaccharide has every bond occurring below the sugar rings while the bonds in cellulose alternate between one bond above the ring and the next below the ring. How can you explain humans' inability to digest cellulose?
A) The enzyme that breaks down starch can only fit the specific bond configuration of bonds below the ring.
B) Humans do not eat cellulose.
C) The acidic molecules found in stomach acid cannot act on the bonds that are above the sugar rings in cellulose.
D) The alternating bonds make the cellulose molecule too large and bulky to enter cells for digestion.
E) Cellular respiration is only capable of breaking down specific bonds.

Question

Quizplus · Accepted Answer

The enzyme that breaks down starch in humans is specific to the alpha linkage of glucose molecules found in starch. Cellulose has beta linkages, which this enzyme cannot break down, explaining why humans cannot digest cellulose.

Both Starch and Cellulose Are Made by Stringing Together Many