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1A
MOLECULES AND THEIR INTERA
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INTERACTION
O BIOL
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RELEV
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RELEVANT
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BIOLOGY
COMMUNICATION BASED QUESTIONS
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Following is an amino acid consensus sequence. DLIY[AG]PRM{W}FMIL. Here [AG] and {w} signify
(a) [AG]= Ala and Gly; {W}= Any amino acid except Trp
(b) [AG]= Any amino acid except Ala and Gly; {W}= Trp
(c) [AG]= Ala or Gly; {W}= Trp
(d) [AG]= Ala or Gly; {W}= Any amino acid except Trp
The DNA of a deletion mutant of λ bacteriophage has a length of 15 µm instead of 17 µm. How many base pairs
are missing from this mutant?
(a) 3342 bp
(b) 4156 bp
(c) 5882 bp
(d) 6750 bp
Water is an excellent solvent for polar molecules. The reason is that H2O
(a) Greatly strengthen electrostatic forces
(b) Greatly weakens electrostatic forces
(c) Greatly strengthen hydrogen bond formation
(d) Greatly weakens hydrophobic interaction
Histones have very high percentage of arginine and lysine (15-30%). For this class of proteins which of the
following reagents would be suitable for peptide sequencing of that histone protein?
(a) CNBr
(b) Trypsin
(c) N-Bromosuccinamide
(d) Chymotrypsin
Which of the following statements is true regarding hydrogen bond?
(a) 09% covalent + 91% electrostatic
(b) 10% covalent + 90% electrostatic
(c) 01% covalent + 99% electrostatic
(d) 05% covalent + 95% electrostatic
Which of the following φ and ∪|value could correctly feature a secondary structure of hypothetical protein on the
basis of Ramachandran plot?
(a) Parallel β sheet: φ = +110; ∪| = +120
(b) Right handed π helix: φ = +54 ; ∪| = -65
(d) Left handed α helix: φ = +55; ∪| = -42
(c) Right handed 310 helix: φ = -43; ∪| = -23
Which of the following statements is true regarding water ionization?
(a) Pure H2O is never ionized
(b) Pure H2O is fully ionized
(c) Pure H2O is more than 50% ionized
(d) Pure H2O is slightly ionized
In which of the following biochemical reaction, entropy will increase?
(a) When O2 is dissolved in H2O
(b) When melted wax is dissolved in H2O
(c) When NaCl is dissolved in H2O
(d) When benzene is dissolved in H2O
There are two solutions namely A and B. They differ in pH by 3 unit. This means
(a) Solution A has 3 times [H+] than solution B
(b) Solution A has 30 times [H+] than solution B
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Advanced Guide for NET Life Science
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(c) Solution A has 300 times [H+] than solution B
(d) Solution A has 1000 times [H+] than solution B
Which of the following is true regarding the concentration of H2O?
(a) Conc. of H2O is higher in solution than in pure H2O
(b) Conc. of H2O is lower in solution than in pure H2O
(c) Conc. of H2O in solution and in pure H2O are same
(d) None of these
Specific heat of H2O is useful to cells as it allows H2O to act as a heat buffer. What should be the nature of
specific heat of H2O in order to be useful for the cell?
(a) High
(b) Moderate
(c) Low
(d) Depend upon the environment
An enzyme mediated hypothetical reaction is shown in the following?
Where k1 = 1 x 106 M-1 × sec-1
k-1 = 3 × 104 sec-1
kcat = 102 sec-1
k2 = 4 × 103 M-1 × sec-1
k-2 = 1.5 × 102 sec-1
Calculate Ks
(a) 3 × 10-2 M
(b) 7 × 10-4 M
(d) 4.5 × 10-7 M
(c) 3.5 × 10-5 M
EtBr is an intercalating agent commonly used in molecular biology laboratory. How it acts when EtBr is used as
fluorescent tag?
(a) It is intercalated by 2.5bp DNA and will increase 27% length of dsDNA
(b) It is intercalated by 2.1bp DNA and will increase 23% length of dsDNA
(c) It is intercalated by 3.5bp DNA and will decrease 27% length of ssDNA
(d) It is intercalated by 3.2bp DNA and will increase 29% length of ssDNA
In a stretch of DNA molecule where twisting no. is 35 and linking no. is 33. If the DNA is exposed to DNA gyrase
and DNA topoisomerase separately, what will be the final linking no respectively
(a) 31, 34
(b) 34, 31
(c) 37, 34
(d) 34, 37
Suppose a molecule of haemoglobin were bound by several different antibodies: one at each BPG binding site,
one at each amino terminus of the α subunits and one at each carboxy terminus of the α subunits. How many total
antibody molecules would be found?
(a) 3
(b) 5
(c) 6
(d) 10
What is the dielectric constant of H2O?
(a) 1
(b) 37
(c) 80
(d) 100
The structure of deoxyhaemoglobin is stabilized by each of the following interactions except
(a) BPG binding
(b) Salt bridges between acidic and basic side chains
(c) Coordination of the heme with the distal histidine (d) Hydrophobic interaction
Molecules and their Interaction Relevant to Biology
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What would happen if you treat haemoglobin with a detergent like urea?
(a) α2β2 to α2 plus β2
(b) α2β2 to αβ plus αβ
(c) α2β2 to 2α plus 2β
(d) α2β2 to α2 plus 2β
Which of the following is a major force of stabilization in 3D structure of globular protein?
(a) Peptide bond
(b) Hydrogen bond
(c) Hydrophobic interaction
(d) D-sulfide bond formation
Which of the following amino acid differs structurally by single group variation only?
(a) Ser → Thr
(b) Asn → Asp
(c) Leu → Ile
(d) Val → Leu
C – N bond distance in a peptide bond is
(b) 1.23 A0
(a) 1.13 A0
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(c) 1.32 A
(d) 1.43 A0
Which of the following statement is said to be in favor of strong hydrogen bond formation?
(a) When bonded molecules are oriented to maximize ionic interaction
(b) When bonded molecules are oriented to maximize electrostatic interaction
(c) When bonded molecules are oriented to maximize dipole dipole interaction
(d) When bonded molecules are oriented to maximize hydrophilic interaction
A stretch of polypeptide is depicted in the following. Which region of the polypeptide would likely to produce
maximum bending (β turn) inside the chain?
Ala-Tyr-Met-Val-Pro-Cys-His-Leu-Gly-Ser-Thr-Ile-Met-Pro-Gly
R1
R2
R3
R4
(a) R1
(b) R2
(c) R3
(d) R4
During trypsin activation, which modification in the amino acid takes place
(a) Elimination of first 7 amino acid from N terminal
(b) Elimination of last 7 amino acid from C terminal
(c) Elimination of first 15 amino acid from N terminal
(d) Elimination of last 15 amino acid from C terminal
Which amino acids are seen in abundance in elastin protein?
(a) Gly-Cys-Tyr
(b) Gly-Ala-Val
(c) Met-Glu-Thr
(d) His-Arg-Lys
An uncompetitive inhibitor of enzyme binds to
(a) Active site of the enzyme
(b) Other than active site of the enzyme
(c) Enzyme substrate complex
(d) Amino terminal of the enzyme
Which of the following correctly shows Eadie Hofstee plot of enzyme kinetics?
(a) V vs V/[S]
(b) 1/V vs 1/S
(d) V vs 1/[S]
(c) [S]/V0 vs [S]
Which of the following is true?
(a) NAG6 → NAG3 + NAG3
(b) NAG6 → NAG2 + NAG4
(c) NAG6 → NAG4 + NAG2
(d) NAG6 → NAG + NAG5
Km which specifies affinity of enzyme with substrate when
(a) K2 >> K1
(b) K1 >> K2
(c) K2 << K-1
(d) K-1 >> K2
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Advanced Guide for NET Life Science
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The catalytic triad of chymotrypsin is
(a) Ser His Asp
(b) Ser Asn His
(c) Gln Lys Gly
(d) Asp Asn Thr
Which of the following statement is correct?
(a) H2O is effective in screening the hydrophilic interaction between dissolved ions because it has a high
dielectric constant.
(b) H2O is effective in screening the hydrophilic interaction between dissolved ions because it has a low
dielectric constant.
(c) H2O is effective in screening the electrostatic interaction between dissolved ions because it has a high
dielectric constant.
(d) H2O is effective in screening the electrostatic interaction between dissolved ions because it has a low
dielectric constant.
Butanol has a relatively high boiling point i.e. 1070C compared to butane (-0.50C). This phenomenon can be
explained by
(a) H atom covalently bonded to C atom do not participate in H bonding, because C is only slightly more
electronegative than H.
(b) H atom covalently bonded to C atom participate in H bonding, because C is only slightly more electronegative
than H.
(c) H atom covalently bonded to C atom do not participate in H bonding, because C is highly electronegative
than H.
(d) H atom covalently bonded to C atom participate in H bonding, because C is highly electronegative than H.
Which molecule binds to the active site of the enzyme?
(a) Noncompetitive inhibitor
(b) Competitive inhibitor
(c) Uncompetitive inhibitor
(d) Irreversible inhibitor
What is the net charge of the following polypeptide Asp-Arg-Trp-Leu-Gly-Val-Ala-Lys-Pro-Met at pH 3?
[pKa of N-terminal = 9.67, pKa of C-terminal = 2.34, pKR of Asp = 3.65, pKR of Lys = 10.53, pKR of Arg =
12.48]
(a) +2
(b) -2
(c) +4
(d) -4
SDS interferes with
(a) Hydrophilic and ionic interaction
(b) Hydrophobic and ionic interaction
(c) Hydrogen bond and ionic interaction
(d) Hydrophilic and hydrogen bond
Suppose dielectric constant of H2O is X. This means
(a) H2O increases the strength of hydrogen interaction by a factor X
(b) H2O diminishes the strength of hydrogen interaction by a factor X
(c) H2O increases the strength of electrostatic interaction by a factor X
(d) H2O diminishes the strength of electrostatic interaction by a factor X
The bond order of peptide bond (C-N)
(a) n = 2
(b) n = 3
(c) 2 < n < 3
(d) 1 < n < 2
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An antibody binds to antigen with a Kd of 5 × 10 M. At what concentration of antigen will θ be 0.2?
(a) 1 × 10-8 M
(b) 1 × 10-5 M
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(c) 5 × 10 M
(d) 5 × 10-5 M
Hopkins cole biochemical test is performed to identify
(a) Trp
(b) Tyr
(c) Phe
(d) Cys