Chapter 24 Multiple Choice Questions

* not completed

. Which is the correct chair form of the β anomer of D-mannose?

correct incorrect

correct incorrect

correct incorrect

correct incorrect

* not completed

. Which carbon becomes the anomeric carbon of glucose in its pyranose form?

C1 correct incorrect

C2 correct incorrect

C5 correct incorrect

C6 correct incorrect

* not completed

. Which of the following statements regarding the reducing ability of a sugar is wrong?

The aldehyde group of a saccharide is responsible for its reducing properties. correct incorrect

Ketoses are not reducing sugars because they are not aldehydes. correct incorrect

D-Glucose in predominantly in a cyclic hemiacetal form but it is a reducing sugar through the acyclic form with which the hemiacetal is in equilibrium. correct incorrect

A methyl glucoside is not a reducing sugar. correct incorrect

* not completed

. The following are the four heteroaromatic bases found in DNA. Which base pair can form three hydrogen bonds?

A-C correct incorrect

A-T correct incorrect

G-C correct incorrect

G-T correct incorrect

* not completed

. Which of (a)-(d) is complementary to the DNA segment 5'-ATGAGCCAT-3'?

5'-TACTCCGTA-3' correct incorrect

5'-TACTCGGTA-3' correct incorrect

5'-TCATCGGTA-3' correct incorrect

5'-TACTGCGTA-3' correct incorrect

* not completed

. Which naturally occurring α-amino acid is achiral?

glycine correct incorrect

glutamine correct incorrect

leucine correct incorrect

serine correct incorrect

* not completed

. Which structure is wrong for an L-α-amino acid?

correct incorrect

correct incorrect

correct incorrect

correct incorrect

* not completed

. The Edman degradation for the determination of peptide sequences involves a reaction using phenyl isothiocyanate to give a phenylthiohydantoin which identifies the N-terminal amino acid unit.

Which of (a)-(d) shows a compound or partial structure which is not involved in reactions of the Edman degradation?

correct incorrect

correct incorrect

correct incorrect

correct incorrect

* not completed

. The following is a structure of menthol without showing stereochemistry. How many chirality centres does menthol have and how many stereoisomers are possible? Choose the correct combination of numbers.

3 centres and 9 isomers correct incorrect

3 centres and 8 isomers correct incorrect

3 centres and 6 isomers correct incorrect

2 centres and 4 isomers correct incorrect

* not completed

. Which of the following statements is wrong?

The configuration of L-serine is S, but that of L-cysteine is R. correct incorrect

Saturated fatty acids have generally lower melting points than the unsaturated fatty acids. correct incorrect

The anions of fatty acid salts (soaps) have a hydrophilic polar end and a hydrophobic hydrocarbon chain, while phospholipids have two hydrophobic chains. correct incorrect

A sesquiterpene is an unsaturated hydrocarbon with 15 carbon atoms. correct incorrect

* not completed

. Which is the correct chair form of the α anomer of D-galactose?

correct incorrect

correct incorrect

correct incorrect

correct incorrect

* not completed

. Which is the correct assignment of configurations of chirality centres, C2-C5, of D-glucose?

2R, 3S, 4R, 5R correct incorrect

2S, 3R, 4S, 5S correct incorrect

2R, 3R, 4R, 5R correct incorrect

2S, 3S, 4R, 5R correct incorrect

* not completed

. Which of the following is not a reducing sugar?

D-fructose correct incorrect

D-ribose correct incorrect

cellobiose correct incorrect

sucrose correct incorrect

* not completed

. Which of the following monosaccharides gives an optically inactive product upon oxidation with HNO₃?

D-glucose correct incorrect

D-mannose correct incorrect

D-galactose correct incorrect

D-fructose correct incorrect

* not completed

. How many chirality centres does S-adenosylmethionine (SAM) have?

3 correct incorrect

4 correct incorrect

5 correct incorrect

6 correct incorrect

* not completed

. Which of (a)-(d) is complementary to the DNA segment 5'-ACGTAATC-3'?

5'-TGCATTCG-3' correct incorrect

5'-TGCATTAG-3' correct incorrect

5'-TGCATAAG-3' correct incorrect

5'-TGACTTAG-3' correct incorrect

* not completed

. Which amino acid has the lowest isoelectric point?

correct incorrect

correct incorrect

correct incorrect

correct incorrect

* not completed

. Which of the following amino acids has the highest isoelectric point?

correct incorrect

correct incorrect

correct incorrect

correct incorrect

* not completed

. Which of (a)-(d) correctly indicates the configurations of the two chirality centres, C2 and C3, of sphingomyelin?

2S,3R correct incorrect

2R,3S correct incorrect

2S,3S correct incorrect

2R,3R correct incorrect

* not completed

. Which of the following statements is false?

Natural fatty acids contain even numbers of carbon atoms. correct incorrect

Diterpenes contain 10 carbons. correct incorrect

Eicosanoids have structures derived from arachidonic acid. correct incorrect

Arachidonic acid is a C₂₀ unsaturated carboxylic acid. correct incorrect