MSc Biochem/Biotech MCQ-test Feb08
01. Though the presence of self-replicating molecules was essential
for the origin of life, what could be considered as the essential requirement
for the construction of a cell?
A.
DNA.
B.
Membranes.
C.
The presence of proteins, nucleic acids and polysaccharides.
D.
Enzymes.
E.
None of the above are essential.
02. Linolenate is essential to the human diet because humans
lack
A.
a delta-6-desaturase.
B.
a delta-9-desaturase.
C.
a delta-12-desaturase.
D.
the ability to incorporate more than 2 double bonds in a
long-chain fatty acid.
E.
the ability to synthesize fatty acids longer than 16
carbons.
03. Which of the following are examples of isomers?
A.
iodine-125 and iodine-131
B.
glucose and galactose
C.
IgG and IgA
D.
gametes and isogametes
E.
HLA-B12 and HLA-B27
04. Which one of the following statements is TRUE ? Lactose
is a disaccharide containing
A.
alpha-1,4 links
B.
glucose and galactose
C.
glucose and fructose
D.
two glucose units
E.
beta-1,3 links
05. N-linked oligosaccharides in glycoproteins are
covalently linked to the protein backbone through
A.
lysine.
B.
serine.
C.
Threonine
D.
Asparagine
E.
Glutamine
06. Which of the following amino acids is destroyed when a
polypeptide is hydrolyzed in 6M HCl at 110o.
A.
Tryptophan
B.
Isoluecine
C.
Lysine
D.
Serine
E.
Proline
07. Which one of the following statements is FALSE:
A.
Nitric oxide is a second messenger signalling molecule in
vertebrates.
B.
Acetylcholine release from autonomic nerves in blood vessel
walls stimulates endothelial cells to synthesizeNO3
C.
Nitric oxide induces smooth muscle relaxation.
D.
Macrophages produce nitric oxide as a cytotoxic mechanism.
E.
Nitric oxide synthase catalyses the deamination of arginine
to yield citrulline and nitric oxide.
08. Regarding amino-acid
Which one of the following statements is FALSE
A.
Valine has a hydrophobic side chain.
B.
Serine has an hydroxyl group in its side chain.
C.
Proline is an imino acid.
D.
Lysine has a negatively-charged side chain.
E.
The side chain of histidine has a net positive charge at pH7
09. Which one of the following statements is TRUE ?
A.
Chloroplasts are green because they contain chloroform.
B.
Chloroplasts are found in plants, green algae and fungi.
C.
The thylakoid vesicles are the site of photosynthesis.
D.
Mitochondria and chloroplasts can be free-living organisms.
E.
The anaerobic phase of respiration takes place in
mitochondria.
10. Which of the following is NOT characteristic of
restriction enzymes?
A.
They can cut DNA in a staggered fashion leaving cohesive
ends.
B.
They recognize specific sequences.
C.
They are bacterial enzymes.
D.
They cut both DNA and RNA.
E.
They are endonucleases
11. The accumulation of citric acid will tend to
A.
activate the glycolysis
B.
inhibit glycolysis
C.
not affect glycolysis
D.
randomly affect the glycolytic rate
E.
will reverse the glycolysis
12. Which one of the following statements is true:
A.
The ratio of purines to pyrimidines in double-stranded DNA
is 2:1 (because purines are larger than pyrimidines)
B.
The ratio of G to A in double-stranded DNA is 1:1
C.
The ratio of T in double-stranded DNA to U in
single-stranded RNA is 1:2
D.
The ratio of G to C in single-stranded RNA is 1:1
E.
The ratio of G to C in double-stranded DNA is 1:1
13. Glucose is radiolabeled at its 1 position and fed to an
organism. Where does the label end up in serine?
A.
The alpha carboxylate
B.
The alpha carbon
C.
The hydroxymethyl sidechain
D.
None of these
14. The products of one
cycle of the urea cycle are
A. 1 molecule
of urea, 1 molecule of ammonia, 1 molecule of ATP and 1 molecule of fumaric
acid
B. 1 molecule
of fumaric acid, 1 molecule of urea, 1 molecule of AMP, 2 molecules of ADP
C. 1 molecule
of aspartic acid, 1 molecule of ammonia, 1 molecule of carbon dioxide, 1
molecule of ATP
D. 1 molecule
of aspartic acid, 1 molecule of ammonia, 1 molecule of fumaric acid, 1 molecule
of ATP
15. Compared to the uncatalyzed
reaction, enzymes cannot change the
A. equilibrium of a reaction.
B.
temperature optimum of a
reaction.
C.
pH optimum of a reaction.
D.
stereospecificity of a reaction.
E.
rate of a reaction.
16. The
transition state of a catalyzed reaction is
A.
bound very weakly to the catalyst.
B.
lower in energy than that of an uncatalyzed reaction.
C.
higher in energy than that of an uncatalyzed reaction.
D.
lower in energy than the reaction substrate.
E.
a highly-populated intermediate on the reaction pathway.
17. All of the carbon and nitrogen atoms of the pyrimidine
ring are supplied by which of the groups of compounds listed below?
A.
glutamate, glycine
B.
glycine, aspartate
C.
glutamine, N-10 formyl tetrahydrofolate
D.
carbamoyl phosphate, ammonia
E.
carbamoyl phosphate, aspartate
18. This enzyme first recognizes allopurinol as a substrate
and is then inhibited by the product of enzyme catalysis.
A.
PRPP synthetase
B.
Hypoxanthine-guanine phosphoribosyl transferase
C.
Adenosine deaminase
D.
PRPP amidotransferase
E.
Xanthine oxidase
19. In the standard protocol for polyacrylamide gel
electrophoresis in the presence of sodium dodecyl sulfate(SDS), the amount of
SDS that binds to each protein depends primarily on
A.
the molecular weight of the protein.
B.
the number of lysine and arginine residues in the protein.
C.
the isoelectric point of the protein.
D.
the concentration of SDS.
E.
the pH of the gel buffer.
20. In collagen, replacement of glycine in the third
position with any other amino acid disrupts the triple helix because :
A.
the number of interchain covalent crosslinks is decreased.
B.
steric hindrance prevents interactions between polypeptide
chains.
C.
intrachain hydrogen bonding is destabilized.
D.
ionic interactions between oppositely charged amino acids
are weakened.
E.
the number of disulfide bonds in N- and C-terminal regions
is decreased.
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(Students are request to email answers along with their name, place, and name of
institution. A merit list along with
the answers to this test will be posted on March 1, 2008)
Answer key to MSc Biochem/Biotech MCQ-test: Jan, 2008