Deck 7: Carbohydrates

Question 1

Which of the following is not a carbohydrate?

A)

B)
C)

D)

E)

Answer 1

B

Question 2

Which of the following carbohydrates does not belong to the family of naturally occurring sugars?

A)

B)

C)

D)

E)

Answer 2

D

Question 3

The compound is an epimer of which of the following molecules?

A)
B)
C)
D)
E)

Answer 3

A

Question 4

Which of the following structures is the $\beta$ -anomer of D-glucose?

A)

B)

C)

D)
E)

Question 5

Which of the following is a $\delta$ -lactone?

A)

B)

C)

D)

E)

Question 6

Which of the following is an aldonic acid?

A)

B)

C)

D)

E)

Question 7

Which of the following compounds is an aldaric acid?

A)

B)

C)

D)

E)

Question 8

Which of the following is an alditol?

A)

B)

C)

D)

E)

Question 9

Which of the following is a glycoside?

A)
B)

C)

D)

E)

Question 10

Which of the following carbohydrates is a nonreducing sugar?

A) Glucose
B) Fructose
C) Lactose
D) Sucrose
E) Ribose

Question 11

The preferred energy source of the brain is __________.

A) fructose
B) glucose
C) arabinose
D) maltose
E) sucrose

Question 12

The two most common deoxy sugars are deoxyribose and __________.

A) L-fucose
B) deoxyglucose
C) deoxyarabinose
D) L-sorbose
E) D-sorbose

Question 13

Which of the following sugars contains a $\beta$ -1,4-linkage?

A) Cellulose
B) Glucose
C) Amylose
D) Sucrose
E) Maltose

Question 14

Oligosaccharides usually contain between __________ and __________ simple sugar units.

A) 6, 8
B) 2, 10
C) 1, 10
D) 3, 10
E) 7, 10

Question 15

Amylopectin is a form of __________.

A) cellulose
B) lactose
C) starch
D) glycogen
E) amylose

Question 16

The most abundant organic substance on earth is __________.

A) starch
B) cellulose
C) sucrose
D) glucose
E) Both B and D are correct.

Question 17

Which of the following is not a homoglycan?

A) Cellulose
B) Glycogen
C) Starch
D) Heparin
E) Amylose

Question 18

Which of the following polysaccharides can bind exceptionally large amounts of water?

A) Cellulose
B) Glycogen
C) Starch
D) Heparin
E) Amylose

Question 19

Carbohydrate is thought to enhance the stability of protein molecules by __________.

A) changing the protein's shape to better resist denaturation
B) protecting the underlying protein from the action of proteolytic enzymes
C) using hydrogen bonding to increase the stability of the protein
D) Both A and B are correct.
E) All the above are correct.

Question 20

In glycoproteins carbohydrate is most often linked to threonine, asparagine or __________.

A) serine
B) lysine
C) valine
D) aspartic acid
E) tyrosine

Question 21

Cellulose is indigestible to most animals because __________

A) cellulose is not soluble in water
B) animals lack the enzymes required to hydrolyze the $\beta$ links of the cellulose
C) cellulose has no food value and therefore cannot be digested
D) Both A and B are correct.
E) None of the above are correct.

Question 22

A glycosidic link is chemically an __________.

A) ether
B) ester
C) amide
D) aldehyde
E) ketone

Question 23

Which of the following yields N-acetyl-D-glucosamine on hydrolysis?

A) Cellulose
B) Heparin
C) Chitin
D) Amylopectin
E) Amylose

Question 24

Glycoproteins lack which of the following groups typically found in proteoglycans?

A) Uronic acids
B) Sulfate groups
C) N-Glycosidic linkages
D) Both A and B are correct.
E) All of the above are correct.

Question 25

Glycogen is __________.

A) the main energy storage molecule of animals
B) the main carbohydrate reserve of animals
C) the main carbohydrate found in seeds
D) a form of plant starch
E) Both C and D are correct.

Question 26

Lactose intolerance arises from __________.

A) bacteria in the intestine that produce toxic metabolites
B) the inability of intestinal enzymes to cleave the lactose
C) a sensitivity to galactose
D) a sensitivity to glucose
E) an allergic reaction to glucose

Question 27

Glycoconjugates result from the covalent linkage of carbohydrate to proteins or __________.

A) amino acids
B) lipids
C) nucleotides
D) Both A and B are correct.
E) None of the above are correct.

Question 28

The three most common homoglycans found in nature are cellulose, starch, and __________.

A) amylose
B) lactose
C) fructose
D) glycogen
E) sucrose

Question 29

The two polysaccharides used to store glucose as an energy reserve are starch and __________.

A) glycogen
B) cellulose
C) fructose
D) sucrose
E) maltose

Question 30

The principal structural carbohydrate of plants is __________.

A) starch
B) glycogen
C) cellulose
D) amylose
E) xylulose

Question 31

The accumulation of AGEs is linked to which of the following diseases?

A) Atherosclerosis
B) Arthritis
C) Diabetes
D) Both A and B are correct.
E) All of the above are correct.

Question 32

N-Glycans are linked via a(n) __________ link between the carbohydrate and the amino acid.

A) $\alpha$ -Glycosidic
B) $\beta$ -Glucosidic
C) ester
D) amide
E) Both A and B are correct.

Question 33

Which of the following is not a common sugar found in N-glycans?

A) Mannose
B) Glucose
C) Maltose
D) Fucose
E) Galactose

Question 34

Which of the following is an example of posttranslational modification of proteins?

A) Phosphorylation
B) Acetylation
C) Proteolytic cleavage
D) Glycosylation
E) All of the above are examples of posttranslational modification.

Question 35

The glycome is the __________.

A) total set of sugars and glycans that an organism produces
B) total set of sugars that an organism produces
C) total set of glycans that an organism produces
D) glycoforms produced by a single sugar
E) None of the above are correct.

Question 36

The production of the glycan components of each type of glycoprotein as a series of slightly different forms is referred to as __________

A) glycoformation
B) glycolation
C) microheterogeneity
D) posttranslational modification
E) alternative splicing

Question 37

Translation of the sugar code requires which of the following?

A) Glycoforms
B) Lectins
C) RNA
D) DNA
E) Integrins

Question 38

Reaction of an amino acid with C1 of a cyclic aldose produces which of the following linkages?

A) Ester
B) Amide
C) Glycosidic
D) Imine
E) Schiff base

Question 39

Which of the following terms is not associated with glycation reactions?

A) AGEs
B) Amadori products
C) Adduct
D) Lactose
E) Maillard reaction

Question 40

The principle means of protection of plants against herbivores is __________.

A) taste
B) smell
C) poison
D) mimicry
E) color

Question 41

Of the following primary types of taste perception which is the most important in identifying calorie-dense foods?

A) Sweet
B) Savory
C) Sour
D) Salty
E) A and B are correct.

Question 42

Savory taste detects which of the following?

A) Sugars
B) Amino acids
C) Toxicity
D) Electrolytes
E) Acids

Question 43

Glycomics is defined as __________.

A) the investigation of the structure and function of all glycans in a cell.
B) glycosidology
C) glycology
D) lipology
E) saccariology

Question 44

In an aldohexopyranose how many methyl groups will be incorporated on treatment with methyl iodide?

A) One
B) Two
C) Three
D) Four
E) Five

Question 45

Which of the following sugars lacks a chiral center?

A) Glucose
B) Glyceraldehyde
C) Dihydroxyacetone
D) Ribose
E) Fructose

Question 46

Define the term diastereomers.

Question 47

What is an enediol?

Question 48

What is a reducing sugar?

Question 49

What structural relationship is indicated by the term D-sugar?

Question 50

What is the difference between a heteroglycan and a homoglycan? Give an example of each.

Question 51

What is a function of glycogen?

Question 52

The polymer chains of glycosaminoglycans are widely spread apart and bind large amounts of water. What functional groups of the polymer are responsible for this phenomenon?

Question 53

What role do carbohydrate groups play in maintaining glycoprotein stability?

Question 54

What are function of proteoglycans?

Question 55

Classify D-glyceraldehyde and dihydroxyacetone as enantiomers, diastereomers, epimers or an aldose-ketose pair.

Question 56

Classify D-glucose and D-mannose as enantiomers, diastereomers, epimers, or an aldose ketose pair.

Question 57

Raffinose, the most abundant trisaccharide in nature, occurs in whole grains and numerous vegetables. It is the $\alpha$ -galactosyl derivative of sucrose. Is raffinose a reducing or nonreducing sugar?

Question 58

Define the term reducing sugar. What structural feature does a reducing sugar have?

Question 59

What structural differences characterize cellulose, glycogen and starch?

Question 60

Phosphate esters can form at position 2 to 6 of an aldohexose but not in position 1. Explain.

Question 61

Suggest a reason why sorbitol prevents water loss in candy.

Question 62

What sugar is produced by the epimerization of galactose?

Question 63

Sucrose does not undergo mutarotation. Explain.

Question 64

Treatment of fructose with methyl iodide produces 1,3,4,6,-tetra-O-methylfructose
What does this information tell you about the ring structure of fructose?

Question 65

Why is it advantageous for a plant toxin to elicit a bitter taste when an animal eats the plant rather than a bland or sweet taste?

Question 66

How does glycosylation improve the water solubility of a water-insoluble molecule?

Question 67

Toxic compounds in plants frequently have bitter tastes that are detectable at very low concentrations. The sweet taste of carbohydrates is only detectable at much higher levels. Can you suggest a reason why this is true?

Question 68

The simplest chiral aldose has three carbon atoms, but the simplest chiral ketose has four carbons. Explain. Include structures in your answer.

Question 69

Normally, the formation of an acetal requires the incorporation of two alcohol units. Formation of a sugar acetal requires only the incorporation of one additional molecule of alcohol. Explain.

Question 70

1-Methylglucose is a nonreducing sugar, whereas 2-methylglucose is a reducing sugar. Explain.

Question 71

How does glycation of red blood cells serve as a measure of long term blood glucose levels?

Question 72

What is the smallest ketose that can form a stable ring?

Question 73

Five- and six-membered ring carbohydrate hemiacetals and hemiketals are reasonably stable and can be easily isolated in contrast to a typical organic acetal. Account for this difference in stability.

Question 74

Polysaccharides can form stable gels that contain immobilized water. How does the polysaccharide immobilize the water?

Question 75

There are two chemically distinct forms of glucose. How is it possible for a single molecule to behave as two distinct molecules?