Both starch and cellulose are made by stringing together many glucose molecules. However, while starch is easily digested by humans, cellulose is indigestible. The starch polysaccharide has bonds occurring below the sugar rings, while the bonds in cellulose alternate above the ring and below the next ring. How can you explain humans' inability to digest cellulose? Multiple Choice1. The enzyme that breaks down starch can only fit the specific bond configuration of bonds below the ring. 2. Humans do not eat cellulose. 3. The acidic molecules found in stomach acid cannot act on the bonds that are above the sugar rings in cellulose. 4. The alternating bonds make the cellulose molecule too large and bulky to enter cells for digestion. 5. Cellular respiration is only capable of breaking down specific bonds.

1 - The enzyme that breaks down starch can only fit the specific bond configuration of bonds below the ring.

Explanation:

The major component in the plant cell walls is cellulose. Cellulose is a linear polysaccharide (glucose monosaccharide units). The acetal linkage in cellulose is beta, distinguishing it from from starch. This bond difference is what makes digesting cellulose impossible as humans do not have the appropriate enzymes for breaking down the beta linkage in cellulose.

There are 2 types of Glycosidic bonds:

A (alpha) - 1,4 bond B (beta) - 1,4 bond

The alpha bond can be broken down by enzymes present in the digestive tract of humans. An example of these enzymes is amylase.

Animals such as cows, can digest cellulose in plants as a special enzyme for breaking down the beta bond is present in their digestive system.