BIOCHEM CHAPTER 7 EXAM 6
Carbohydrate characteristic chemical features include all EXCEPT:
a. the potential to form multiple hydrogen bonds.
b. the existence of one or more asymmetric centers.
c. the capacity to form polymeric structures.
d. the ability to exist in either linear or ring structures.
e. all are true. - CORRECT ANSWER-E
Which of the following sugars is an aldopentose?
a. galactose
b. ribulose
c. ribose
d. xylulose
e. mannose - CORRECT ANSWER-C. ribose
If carbon 1 is the carbonyl group of an aldohexose, which carbon determines if the
sugar is a D- or L- stereoisomer? - CORRECT ANSWER-5
The enantiomer of D-mannose would be: - CORRECT ANSWER-L-mannose
Xylulose is an epimer of: - CORRECT ANSWER-ribulose
The formation of cyclic structures in sugars with creation of an additional asymmetric
center results from an alcohol reacting with a(n): - CORRECT ANSWER-aldehyde or
ketone
A cyclic hemiacetal with a six-membered oxygen-containing ring is referred to as a(n): -
CORRECT ANSWER-pyranose
Glucose most commonly forms which of the following structures? - CORRECT
ANSWER-a pyranose using the hydroxyl group on carbon 5
All of the following statements about cyclic sugars are true EXCEPT:
a. The α-anomer has the -OH of the anomeric carbon positioned on the opposite side of
the sugar ring from the -CH2OH.
b. The five and six membered rings are more frequently observed due to stability.
c. In a chair conformation, the predominant form has the bulkiest substituents occupying
axial positions.
d. The carbonyl carbon becomes a chiral center.
e. They can be formed by the intramolecular reactions to hemiacetals or hemiketals. -
CORRECT ANSWER-C
As a result of mutarotation, D-glucose exists in all of the following forms EXCEPT:
, a. L-glucopyranose.
b. β-anomer.
c. free aldehyde.
d. α-anomer.
e. all are true. - CORRECT ANSWER-A
β-D-glucopyranose in the chair form is the most widely occurring form of glucose in
nature and it has the following characteristics EXCEPT:
a. forms a six-membered ring.
b. carbon 6 is above the plane of the chair.
c. all of the -OH groups are equatorial.
d. the anomeric carbon has a hydroxyl that is below the plane of the chair.
e. all axial positions are occupied by -H. - CORRECT ANSWER-D
All of the statements about the following pairs of sugars are correct EXCEPT:
a. Galactose and mannose are diastereomers.
b. L-galactose and D-galactose are enatiomers.
c. Glyceraldehyde and dihydroxyacetone are stereoisomers.
d. Glucose and mannose are epimers.
e. Glucose has fewer chiral centers than fructose - CORRECT ANSWER-E
Individuals with uncontrolled diabetes mellitus may have __________ levels of blood
___________ so they test their blood for ________________. - CORRECT ANSWER-
elevated; glucose; reducing sugars
Sugar alcohols include all of the following EXCEPT:
a. ribitol.
b. sorbitol.
c. fucose.
d. mannitol.
e. glycerol. - CORRECT ANSWER-C
A constituent of the flavin coenzymes is - CORRECT ANSWER-ribitol
16. Honey is characteristically composed predominantly of - CORRECT ANSWER-c.
fructose and glucose
17. All of the following are parts of the honeybee's processing of honey EXCEPT:
a. producing a small amount of gluconic acid.
b. concentrating the sugars to a supersaturated state.
c. conversion of some glucose and fructose into sucrose.
d. conversion of most of the fructose to the β-D-fructopyranose form.
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