MCAT Biology Question — Cellulose | Next Step Test Prep MCAT Biology Question — Cellulose | Next Step Test Prep

Fields marked with an * are required

Schedule a Free Tutoring Consultation

A Next Step Academic Manager will contact you within 1 business day or call us now at 888-530-6398.

Contact us

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Save

Although linked at the same carbons as starch and glycogen, cellulose is indigestible to humans. This is a result of the:

 

  1. alpha-linkage from carbons 2 to 6 of D-glucose.
  2. beta-linkage at carbons 2 to 6 of D-glucose.
  3. alpha-linkage at carbons 1 to 4 of D-glucose.
  4. beta-linkage at carbons 1 to 4 of D-glucose.

 

 

Explanation:

 

In humans, glycogen is broken down by debranching enzyme (alpha 1,6 linkages) and phosphorylases (alpha 1,4 linkages). Starch is broken down at alpha 1,4 linkages by alpha-amylase found in saliva and pancreatic secretions. Cellulose cannot be broken down by humans because it is beta-linked at carbons 1 to 4. For the MCAT: Alpha-1,4 linked glucose indicates digestible glycogen and starch, and beta-1,4 linkage indicates indigestible cellulose.

 

  1. alpha-linkage from carbons 2 to 6 of D-glucose, incorrect.
  2. beta-linkage at carbons 2 to 6 of D-glucose, incorrect.
  3. alpha-linkage at carbons 1 to 4 of D-glucose, incorrect.
  4. beta-linkage at carbons 1 to 4 of D-glucose, correct.

 

Want more practice?

Fields marked with an * are required

Sign up for our MCAT Question of the Day!

X