Deck 6: Carbohydrates I

Question 1

The molecular formula for a monosaccharide is _____.

A) C_nH_2n+2O_n
B) C_nH_2nO_n.
C) C_nH_2nO_n
D) C_nH_2n+2O_n.
E) none of the above

Answer 1

C_nH_2nO_n.

Question 2

Glucose and galactose are _____ of each other.

A) epimers
B) enantiomers
C) diastereomers
D) anomers
E) none of the above

Answer 2

epimers

Question 3

Which of the monosaccharides seen below are L sugars?

A) A and B
B) A and C
C) B and C
D) C and D
E) A, B and C

Answer 3

C and D

Question 4

The structure below shows a Fischer projection of D-Idose.
Which of the structures below represents $\beta$ -D-Idopyranose?

A)
B)
C)
D)
E)

Question 5

In the following structure, which carbon is the anomeric carbon?

A) A
B) B
C) C
D) D
E) E

Question 6

The _____ sugars are monosaccharides in which a hydroxyl group is replaced with a hydrogen atom.

Question 7

Any sugar that has a free aldehyde group is called a(n) _____.

A) reducing sugar
B) nonreducing sugar
C) ketose
D) aldohexose
E) alditol

Question 8

Describe the properties, structures, and functions of the major categories of monosaccharides.

-Which structure(s) shown in the figure above represent reducing sugar(s)?

A) A
B) D
C) C and D
D) A, B, C, and D
E) A, B, and C

Question 9

The disaccharide commonly found in dairy products is _____.

Question 10

Amylopectin contains primarily _____ glycosidic bonds with _____ glycosidic bonds as branch points.

A) $\alpha$ (1 $\rightarrow$ 4); $\alpha$ (1 $\rightarrow$ 2)
B) $\alpha$ (1 $\rightarrow$ 4); $\alpha$ (1 $\rightarrow$ 6)
C) $\alpha$ (1 $\rightarrow$ 4); $\beta$ (1 $\rightarrow$ 6)
D) $\beta$ (1 $\rightarrow$ 4); $\alpha$ (1 $\rightarrow$ 4)
E) $\beta$ (1 $\rightarrow$ 4); $\alpha$ (1 $\rightarrow$ 6)

Question 11

Which of the following is the major difference between glycogen and amylopectin?

A) Glycogen contains $\alpha$ -glycosidic bonds; amylopectin contains $\beta$ -glycosidic bonds.
B) Glycogen is branched; amylopectin is linear.
C) Glycogen contains a reducing end; amylopectin does not.
D) Glycogen contains about twice the number of branch points as amylopectin.
E) Glycogen is found in plants; amylopectin is found in animals.

Question 12

Which of the following are characteristic of cellulose?

A) highly extended chains
B) $\beta$ (1 $\rightarrow$ 4) glycosidic bonds
C) extensive hydrogen bonding between individual molecules
D) unbranched polymer
E) all of the above

Question 13

Unlike proteins and oligonucleotides, polysaccharides _____.

A) are readily metabolized in the absence of specialized enzymes
B) often have branched structures
C) are achiral
D) are always completely water soluble
E) are components of every known living organism

Question 14

_____ is a homopolymer composed of $\beta$ (1-4)-linked N-acetyl-D-Glucosamine residues that is the principle structural component of the exoskeleton of various groups of invertebrates.

Question 15

Both $\alpha$ (1 $\rightarrow$ 4) and $\alpha$ (1 $\rightarrow$ 6) bonds can be found in the plant product______.

Question 16

In the catabolic pathway, major nutrients are _____ broken down mainly resulting in more _____ metabolites.

A) exergonically; reduced
B) endergonically; reduced
C) exergonically; oxidized
D) endergonically; oxidized
E) endergonically; phosphorylated

Question 17

Energy is generated during _____, the breakdown of larger molecules into smaller ones, whereas energy is consumed during _____, the building of larger molecules from smaller ones.

A) reduction reactions; oxidation reactions
B) autotrophic reactions; heterotrophic reactions
C) catabolic reactions; anabolic reactions
D) hydrolysis reactions; condensation reactions
E) none of the above

Question 18

The enzyme _____ is the major control point for glycolysis.

Question 19

The process of _____ converts glucose into _____.

A) electron transport; CO₂
B) glycolysis; pyruvate
C) glycogenolysis; glycogen
D) gluconeogenesis; glycogen
E) glycogen synthesis; pyruvate

Question 20

Which of the following enzymes requires ATP as a substrate?

A) phosphofructokinase
B) phosphoglucose isomerase
C) aldolase
D) triose phosphate isomerase
E) enolase

Question 21

Which enzyme is responsible for splitting a hexose into two trioses?

A) enolase
B) phosphoglycerate mutase
C) phosphofructose isomerase
D) triose phosphate isomerase
E) aldolase

Question 22

Which enzyme catalyzes the major regulatory step of glycolysis?

A) hexokinase
B) aldolase
C) glyceraldehyde-3-phosphate dehydrogenase
D) phosphofructokinase
E) phosphoglucose isomerase

Question 23

Which of the following is a potent activator of phosphofructokinase in mammals?

A) fructose-6-phosphate
B) glucose-6-phosphate
C) fructose-2,6-bisphosphate
D) fructose-1,6-bisphosphate
E) glyceraldehyde-3-phosphate

Question 24

The active site of aldolase contains a Lys residue that forms a(n) _____ and a(n) Asp residue that participates in _____ reactions.

A) amide; acid-base
B) Schiff base; acid-base
C) secondary amine; acid-base
D) amide; isomerization
E) Schiff base; isomerization

Question 25

In the reaction catalyzed by aldolase, the bond broken is between C-3 and C-4 of the substrate. Which functional groups are present on these two carbons (C-3 and C-4) in the products?

A) C-3 becomes an alcohol; C-4 becomes a carboxylic acid.
B) C-3 becomes an aldehyde; C-4 becomes a ketone.
C) C-3 becomes an aldehyde; C-4 becomes an alcohol.
D) C-3 becomes an alcohol; C-4 becomes an aldehyde.
E) C-3 becomes a ketone; C-4 becomes an alcohol.

Question 26

Triose phosphate isomerase catalyzes a reaction that is most like that of _____.

A) phosphoglycerate mutase
B) phosphoglucose isomerase
C) hexokinase
D) aldolase
E) enolase

Question 27

What is the name for the process that produces ATP from ADP in glycolysis?

A) substrate-level phosphorylation
B) oxidative phosphorylation
C) autophosphorylation
D) glycolytic phosphorylation
E) cytosolic phosphorylation

Question 28

Glyceraldehyde-3-PO4 is oxidized to _____, which can transfer a phosphate to _____.

A) phosphoenolpyruvate; ADP
B) phosphoenolpyruvate; AMP
C) 1,3-bisphosphoglycerate; ADP
D) 1,3-bisphosphoglycerate; AMP
E) 3-phosphoglycerate; ADP

Question 29

Why is phosphoglycerate kinase still considered a kinase even though ADP is converted to ATP?

A) The enzyme is freely reversible.
B) ATP is the ultimate source of the phosphate that is transferred to ADP.
C) The phosphate is transferred in conjunction with an oxidation reaction.
D) The reaction is metabolically irreversible.
E) None of the above

Question 30

Which of the following compounds is used to produce ATP by substrate-level phosphorylation in glycolysis?

A)

B)

C)

D)

E)

Question 31

What type of enzyme is enolase, which catalyzes the conversion of 2-phosphoglycerate to phosphoenolpyruvate and water?

A) transferase
B) hydrolase
C) ligase
D) lyase
E) oxidoreductase

Question 32

What sort of activity does fructose-1,6-bisphosphate have on pyruvate kinase?

A) no effect
B) competitive inhibitor
C) noncompetitive inhibitor
D) allosteric inhibitor
E) activator

Question 33

Which of the following contains a bond that is used for a substrate-level phosphorylation in glycolysis?

A) fructose-1,6-bisphosphate
B) 1,3-bisphosphoglycerate
C) acetyl phosphate
D) 2,3-bisphosphoglycerate
E) 1-phosphoglycerate

Question 34

What regulatory enzyme of glycolysis is skipped during fructose metabolism?

A) hexokinase
B) phosphoglucose isomerase
C) phosphofructokinase
D) pyruvate kinase
E) fructose metabolism does not skip any steps of glycolysis

Question 35

If a cell were given glucose labeled at C-3 with ¹⁴C, which carbon(s) of pyruvate would contain the label?

A) 1
B) 2
C) 3
D) 1 and 3
E) 2 and 3

Question 36

What pathway is used to make glucose from other metabolites such as pyruvate or lactate?

A) glycogen synthesis
B) glycogen degradation
C) glycolysis
D) pentose phosphate pathway
E) gluconeogenesis

Question 37

Glucose can be synthesized from noncarbohydrate precursors by______.

Question 38

Which of the following is true concerning the reaction catalyzed by pyruvate dehydrogenase?

A) It is an oxidative decarboxylation.
B) It is activated by high concentrations of ATP.
C) The enzyme contains a pyridoxal phosphate prosthetic group.
D) The reaction is an anaplerotic reaction because it can replace citric acid intermediates that are removed for other pathways.
E) The enzyme contains two different types of subunits.

Question 39

Which of the following pyruvate dehydrogenase enzymes is correctly paired with the coenzyme that is associated with it?

A) E1: coenzyme A
B) E2: thiamine pyrophosphate
C) E3: FAD
D) E2: NAD⁺
E) E3: lipoamide

Question 40

Which of the following coenzymes is directly responsible for the oxidation of the hydroxyethyl group to the acetyl group?

A) coenzyme A
B) thiamine pyrophosphate
C) FAD
D) NAD⁺
E) lipoamide

Question 41

What type of bond forms when the hydroxyethyl group is transferred to lipoamide?

A) ester
B) amide
C) thioester
D) anhydride
E) none of the above

Question 42

Which of the following is an inhibitor of pyruvate dehydrogenase?

A) CoA
B) pyruvate
C) FADH₂
D) NADH
E) CO₂

Question 43

Under aerobic conditions, pyruvate is converted to _____ by pyruvate dehydrogenase.

A) oxaloacetate
B) ethanol
C) lactate
D) glucose
E) acetyl-CoA

Question 44

What cellular location contains pyruvate dehydrogenase and most of the citric acid cycle enzymes?

A) cytosol
B) mitochondrial matrix
C) inner mitochondrial membrane
D) mitochondrial intermembrane space
E) outer mitochondrial membrane

Question 45

Glycolysis forms _____ under either aerobic or anaerobic conditions.

Question 46

Which enzyme has an intermediate of the form presented below?

A) phosphofructokinase
B) aldolase
C) pyruvate dehydrogenase
D) glyceraldehyde-3-phosphate decarboxylase
E) triose phosphate isomerase