MCAT Biochemistry Practice Test 4: Carbohydrate Structure and Function

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1. When glucose is in a straight-chain formation, it:

  • A. is an aldoketose.
  • B. is a pentose.
  • C. has five chiral carbons.
  • D. is one of a group of 16 stereoisomers.

2. All of the following are true of epimers EXCEPT:

  • A. they differ in configuration about only one carbon.
  • B. they usually have slightly different chemical and physical properties.
  • C. they are diastereomers (with the exception of glyceraldehyde).
  • D. they always have equal but opposite optical activities.

3. Aldonic acids are compounds that:

  • A. can be oxidized, and therefore act as reducing agents.
  • B. can be reduced, and therefore act as reducing agents.
  • C. have been oxidized, and have acted as reducing agents.
  • D. have been oxidized, and have acted as oxidizing agents.

4. The formation of α-d-glucopyranose from β-d-glucopyranose is called:

  • A. glycosidation.
  • B. mutarotation.
  • C. enantiomerization.
  • D. racemization.

5. Ketose sugars may have the ability to act as reducing sugars. Which process explains this?

  • A. Ketose sugars undergo tautomerization.
  • B. The ketone group is oxidized directly.
  • C. Ketose sugars undergo anomerization.
  • D. The ketone group is reduced directly.

6. What is the product of the following reaction?

  • A.
  • B.
  • C.
  • D.

7. Which of the following enzymes cleaves polysaccharide chains and yields maltose exclusively?

  • A. α-Amylase
  • B. β-Amylase
  • C. Debranching enzyme
  • D. Glycogen phosphorylase

8. When the following straight-chain Fischer projection is converted to a chair or ring conformation, its structure will be:

  • A.
  • B.
  • C.
  • D.

9. Why is the α-anomer of d-glucose less likely to form than the β-anomer?

  • A. The β-anomer is preferred for metabolism.
  • B. The β-anomer undergoes less electron repulsion.
  • C. The α-anomer is the more stable anomer.
  • D. The α-anomer forms more in l-glucose.

10. Which two polysaccharides share all of their glycosidic linkage types in common?

  • A. Cellulose and amylopectin
  • B. Amylose and glycogen
  • C. Amylose and cellulose
  • D. Glycogen and amylopectin

11. Which of the following is digestible by humans and is made up of only one type of monosaccharide?

  • A. Lactose
  • B. Sucrose
  • C. Maltose
  • D. Cellobiose

12. The reaction below is an example of one step in:

  • A. aldehyde formation.
  • B. hemiketal formation.
  • C. mutarotation.
  • D. glycosidic bond cleavage.

13. Galactose is the C-4 epimer of glucose, the structure of which is shown below. Which of the following structures is galactose?

  • A.
  • B.
  • C.
  • D.

14. Andersen's disease (glycogen storage disease type IV) is a condition characterized by a deficiency in glycogen branching enzyme. Absence of this enzyme would be likely to cause all of the following effects EXCEPT:

  • A. decreased glycogen solubility in human cells.
  • B. slower action of glycogen phosphorylase.
  • C. less storage of glucose in the body.
  • D. glycogen devoid of α-1,4 linkages.

15. The cyclic forms of monosaccharides are:

I. hemiacetals.

II. hemiketals.

III. acetals.

  • A. I only
  • B. III only
  • C. I and II only
  • D. I, II, and III