Q1 · June 2021 · 2 marks
Which of the following statements for rubredoxin,
- (a) \mathrm{F}_{2}{ }^{+}center has a tetrahedral geometry. A, B and C
- (b) Reduced form of iron is diamagnetic. A, C and D
- (c) \mathrm{F}_{2}{ }^{+}center undergoes Jahn-Teller distortion. C and D only
- (d) It is a [2Fe-2S] cluster. are correct? A and C only 13 BIOINORGANIC CHEMISTRY
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Answer: (d)
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Q2 · 2020 · 2 marks
In the catalytic cycle of Cytochrome \mathbf{P}_{\mathbf{4 5 0}}, the generation of \left[(\text { porphyrin })^{+\bullet} \mathbf{F e}^{\mathrm{IV}}(\mathbf{O})\right] from [(porphyrin) \mathbf{F e}^{\text {III }}(\mathbf{O O H}) ] involves
- (a) One electron oxidation of \left[(\right. porphyrin \left.) \mathrm{Fe}^{\mathrm{III}}(\mathrm{OOH})\right]
- (b) Formation of the intermediate [(porphyrin) \mathrm{Fe}^{\mathrm{IV}}(\mathrm{OH}) ]
- (c) Homolytic O-O cleavage of [(porphyrin) \left.\mathbf{F e}^{\mathbf{I V}}(\mathbf{O O H})\right]
- (d) Heterolytic O-O cleavage of [(porphyrin)Fe™(OOH)]
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Answer: (d)
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Q3 · 2020 · 2 marks
During the binding of \mathrm{O}_{2} to myoglobin (consider 'heme' in xy-plane), the molecular orbital of \mathrm{O}_{2} and atomic orbital of Fe involved in the formation of the \sigma-bond is
- (a) \pi^{*} and d_{z^{2}}
- (b) \pi^{*} and d_{xz}
- (c) \pi and d_{xz}
- (d) \pi and d_{z^{2}}
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Answer: (a)
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Q4 · 2019 · 2 marks
Consider the following transformation, reactions in the context of co-enzyme \mathbf{B}_{\mathbf{1 2}}
- (a) 1, 2-Carbon shift
- (b) Hydration of \mathrm{CO}_{2}
- (c) Benzene to phenol
- (d) dimethyl sulfide to demethyl sulfoxide
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Answer: (d)
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Q5 · 2019 · 2 marks
The metal transferred by bacteria and fungi using siderophores/siderochromes is
- (a) Mo
- (b) Cu
- (c) Fe
- (d) Zn
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Answer: (c)
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Q6 · 2019 · 2 marks
Consider the following statements with respect to Cytochrome P-450
- (a) It has histidine coordinated to iron centre
- (b) It is a membrane bound metalloenzymes
- (c) It has Fe(III) ion in the resting state of the enzyme
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Answer: (c)
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Q7 · Dec 2019 · 2 marks
Choose the correct statements for oxymyoglobin and cytochrome P450 (resting state) from the following:
- (a) Both contain dianion of protoporphyrin-IX A. B and C
- (b) They have same fifth-ligand bonded to metal centre from the protein backbone A, C and D
- (c) They contain single active site A. B and D
- (d) They contain metal ion in +3 oxidation state B and C only
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Answer: (b)
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Q8 · 2019 · 2 marks
Complex(es) which has/have unpaired electron(s) that is equal to that of iron center in oxymyoglobin is/are
- (a) \left[\mathrm{Fe}(\mathrm{ox})_{3}\right]^{3-} A and B
- (b) \left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{3-} B and D
- (c) \left[\mathrm{NiCl}_{4}\right]^{2-} C only
- (d) \left[\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4}\right]^{2+} (Given: ox oxalato) Correct answer is C and D
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Answer: (b)
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Q9 · Dec 2019 · 2 marks
In the catalytic cycle of Cytochrome P450, the generation of [( porphyrin )+\mathrm{FeIV}(\mathrm{O})] from [(porphyrin)FeIII(OOH)] involves
- (a) One electron oxidation of [(porphyrin)FeIII(OOH)]
- (b) Formation of the intermediate [(porphyrin)FeIV(OH)]
- (c) Homolytic O-O cleavage of [(porphyrin)FeIV(OOH)]
- (d) Heterolytic O-O cleavage of [(porphyrin)FeIII(OOH)]
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Answer: (d)
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Q10 · 2018 · 2 marks
Consider the following statements for the oxygenation of hemocyanine:
- (a) Oxidation state of both copper atoms changes by two
- (b) It becomes intense blue from colorless
- (c) Dioxygen is reduced to \mathrm{O}_{2}{ }^{-2}
- (d) The \mu-\eta 2: \eta 2 bond forms between each oxygen and copper atoms.
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Answer: (d)
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Q11 · 2018 · 2 marks
The chelate rings made by macrocyclic ligand in vitamin \mathrm{B}_{12} are
- (a) One five-membered and three six-membered
- (b) Two five-membered and two six-membered
- (c) Three five-membered and one six-membered
- (d) Four six-membered
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Answer: (a)
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Q12 · 2017 · 2 marks
The resonance Raman stretching frequencies (in \mathrm{cm}^{-1} ) of the bound \mathrm{O}_{2} species in oxy hemerthyrin and oxy-hemoglobin, respectively, are
- (a) 850 and 1100
- (b) 750 and 850
- (c) 850 and 850
- (d) 1100 and 850
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Answer: (a)
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Q13 · 2017 · 2 marks
In vitro reaction of an excess of \mathrm{O}_{2} with free heme B in aqueous medium the end product is
- (a) hematin
- (b) \left[\mathrm{O}_{2}{ }^{-}-\mathrm{Fe}\right. (III)-protoporphyrin-IX ]
- (c) heme \mathrm{B}\left(\mathrm{O}_{2}\right)
- (d) oxoferrylprotoporphyrin-IX cation radical
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Answer: (a)
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Q14 · 2017 · 2 marks
Consider the following statements for metallothioneins:
- (a) the contain about 30 \% cysteine residues A, B and C
- (b) they prefer to bind soft metal ions such as Cd(II), Hg(II) and Zn(II) A, B and D
- (c) they are involved in electron transfer reactions A, C and D
- (d) they are low molecular weight proteins Correct statements are B and C
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Answer: (b)
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Q15 · 2017 · 2 marks
Consider the following statements for deoxy-hemerythrin and deoxy-hemocyanin:
- (a) they are involved in \mathbf{O}_{\mathbf{2}} transport in biological systems
- (b) they contain two metal ions in their active site
- (c) active site metal centres are bridged by amino acid residues
- (d) they prefer to bind only one \mathbf{O}_{\mathbf{2}} per active site
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Answer: (a)
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Q16 · 2017 · 2 marks
The correct statement for cytochrome c is
- (a) It is a non-heme protein
- (b) The coordination number of iron in cytochrome \boldsymbol{c} is five
- (c) It is a redox protein and an electron carrier
- (d) It can store or carry dioxygen
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Answer: (c)
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Q17 · 2017 · 2 marks
The number of inorganic sulfides in cubane like ferredoxin and their removal method, respectively, are
- (a) eight and washing with an acid
- (b) four and washing with a base
- (c) eight and washing with a base
- (d) four and washing with an acid
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Answer: (d)
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Q18 · 2016 · 2 marks
In human body cis- platin hydrolyzes to diaqua complex and modifies the DNA structure by binding to
- (a) N-atom of guanine base
- (c) N-atom of adenine base
- (b) O-atom of cytosine base
- (d) O-atom of thymine base
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Answer: (a)
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Q19 · 2016 · 2 marks
Correct combination of number and size of rings present in a metal ion-porphine complex (including metal ion bearing chelate rings) is
- (a) four 5-membered and four 6-membered N-atom of guanine base
- (b) two 5-membered and six 6-membered N-atom of adenine base
- (c) six 5-membered and two 6-membered O-atom of cytosine base
- (d) five 5-membered and three 6-membered 6 O-atom of thymine base
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Answer: (a)
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Q20 · June 2016 · 2 marks
In human body cis- platinhydrolyzes to diaqua complex and modifies the DNA structure by binding to
- (a) N-atom of guanine base
- (b) N-atom of adenine base
- (c) O-atom of cytosine base
- (d) O-atom of thymine base
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Answer: (a)
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Q21 · 2016 · 2 marks
In the catalytic hydration of \mathrm{CO}_{2} by carbonic anhydrase, \mathrm{CO}_{2} first interacts with
- (a) OH group of the active site of the enzyme and then with zinc
- (b) \mathrm{H}_{2} \mathrm{O} of the active site of the enzyme and then with zinc
- (c) zinc of the active site of the enzyme and then with OH group
- (d) zinc of the active site of the enzyme and then with \mathrm{H}_{2} \mathrm{O}
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Answer: (a)
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Q22 · 2016 · 2 marks
The number of inorganic Sulphur (or sulphide) atoms present in the metalloprotein active sites of rubredoxin, 2-iron ferredoxin and 4-iron ferredoxin, respectively, are
- (a) 0, 2 and 4
- (b) 2, 4 and 3
- (c) 0, 4 and 2
- (d) 0,2 and 3
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Answer: (a)
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Q23 · 2016 · 2 marks
From the following transformations,
- (a) Epoxidation of alkene A and B
- (b) Diol dehydrase reaction B, C and D
- (c) Conversion of ribonucleotide-to-deoxyribonucleotide A, B and D
- (d) 1, 2-carbon shift in organic substrates those promoted by coenzyme \mathbf{B}_{\mathbf{1 2}} are A, B and C
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Answer: (b)
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Q24 · 2015 · 2 marks
The biological functions of carbonic anhydrase and carboxypeptidase A, respectively, are
- (a) interconversion of \mathrm{CO}_{2} and carbonates and hydrolysis of peptide bond
- (b) gene regulation and interconversion of \mathrm{CO}_{2} and carbonates
- (c) gene regulation and hydrolysis of peptide bond
- (d) interconversion of \mathrm{CO}_{2} and carbonates and gene regulation
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Answer: (a)
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Q25 · 2015 · 2 marks
The Fe-Nporphyrin bond distances in the deoxy and oxy-hemoglobin, respectively, are
- (a) 2.1 and 2.0 \AA
- (b) 2.0 and 2.0 \AA
- (c) 2.2 and 2.3 \AA
- (d) 2.3 and 2.5 \AA
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Answer: (a)
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Q26 · Dec 2015 · 2 marks
The biological functions of cytochrome \mathrm{P}_{450} and myoglobin are, respectively
- (a) oxidation of alkene and \mathrm{O}_{2} storage
- (b) \mathrm{O}_{4} transport and \mathrm{O}_{2} storage
- (c) \mathrm{O}_{2} storage and electron carrier
- (d) electron carrier and \mathrm{O}_{2} transport
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Answer: (a)
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Q27 · 2015 · 2 marks
Deoxy-hemocyanin is
- (a) heme protein and paramagnetic
- (b) colourless and diamagnetic
- (c) \mathbf{O}_{\mathbf{2}} transporter and paramagnetic
- (d) blue colored and diamagnetic
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Answer: (b)
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Q28 · 2014 · 2 marks
If an enzyme fixes \mathrm{N}_{2}, in plants by evolving \mathrm{H}_{2}, the number of electrons and protons associated with that, respectively are
- (a) 6 and 6
- (b) 8 and 8
- (c) 6 and 8
- (d) 8 and 6
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Answer: (b)
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Q29 · 2014 · 2 marks
Ozone present in upper atmosphere protects people on the earth
- (a) due to its diamagnetic nature
- (b) due to its blue colour
- (c) due to absorption of radiation of wavelength at 255nm
- (d) by destroying chlorofluoro carbons
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Answer: (c)
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Q30 · 2014 · 2 marks
Molybdoenzymes can both oxidize as well as reduce the substrates, because
- (a) Mo(VI) is more stable than Mo(IV)
- (b) Mo(IV) can transfer oxygen atom to the substrate and Mo(VI) can abstract oxygen atom from the substrate
- (c) Conversion of Mo(VI) to Mo(IV) is not favoured
- (d) Mo(VI) can transfer oxygen atom to the substrate and Mo(IV) can abstract oxygen atom from the substrate.
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Answer: (d)
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Q31 · 2014 · 2 marks
The cooperative binding of \mathrm{O}_{2} in hemoglobin is due to
- (a) a decrease in size of iron followed by changes in the protein conformation
- (b) an increase in size of iron followed by changes in the protein conformation
- (c) a decrease in size of iron that is NOT accompanied by the protein conformational changes
- (d) an increase in size of iron that is NOT accompanied by the protein conformational changes
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Answer: (a)
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Q32 · 2014 · 2 marks
The extent of \pi-electron conjugation in macrocyclic rings of (1) heme, (2) coenzyme \mathrm{B}_{12} and (3) chlorophyll follows the order
- (a) (1)>(3)>(2)
- (b) (1)>(2)>(3)
- (c) (3)>(1)>(2)
- (d) (2)>(1)>(3)
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Answer: (a)
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Q33 · 2014 · 2 marks
The number of histidine amino acid nitrogen atoms coordinated to bimetallic active site of oxyhemocyanin, and oxyhemerythrin, respectively, are
- (a) 2, 3 and 3, 3.
- (b) 3, 3 and 2, 3
- (c) 3, 3 and 2, 2
- (d) 2, 4 and 3,2
Oxyhemocyanin (3, 3-histidine amino acids)
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Answer: (b)
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Q34 · 2011-2020 · 2 marks
Identify correct statements for mercury as an environment pollutant.
- (a) Carbanionicbiomethylation converts it to \mathrm{MeHg}^{+}
- (b) Thiol group of cysteine has strong affinity for mercury
- (c) Mercury containing industrial catalyst release caused Minamata disaster
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Answer: (d)
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Q35 · Dec 2014 · 2 marks
Under physiological condition, oxygen is binding to deoxyhemoglobin and deoxymyoglobin, the binding curve and its pH dependence, respectively, are
- (a) Sigmoidal and pH dependent; hyperbolic and pH independent
- (b) Hyperbolic and pH independent:sigmoidal and pH dependent 4
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Answer: (a)
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Q36 · 2013 · 2 marks
The coordination geometry of copper (II) in the type I copper protein plastocyanin is:
- (a) square planar
- (b) tetrahedral
- (c) octahedral
- (d) distorted tetrahedral The coordination geometry of copper (II) in the type I copper protein plastocyanin is distorted tetrahedral
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Answer: (d)
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Q37 · 2013 · 2 marks
The metal ions present in the active site of nitrogenase enzyme co-factor are
- (a) Fe, Mo
- (b) Fe, W
- (c) Fe, Cu
- (d) Fe, Ni
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Answer: (a)
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Q38 · 2013 · 2 marks
Patients suffering from Wilson's disease have
- (a) Low level of Cu-Zn superoxide dismutase
- (b) High level of \mathrm{Cu}-\mathrm{Zn} superoxide dismutase
- (c) Low level of copper-storage protein, ceruloplasmin
- (d) High level of copper-storage protein, ceruloplasmin
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Answer: (c)
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Q39 · 2013 · 2 marks
L-DOPA is used for treatment of
- (a) tuberculosis
- (b) Parkinson's disease
- (c) diabetes
- (d) cancer
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Answer: (b)
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Q40 · Dec 2013 · 2 marks
Oxidised form of enzyme catalase (structure A); prepared by the reaction of \mathrm{[Fe(P)]^+} (P = porphyrin) with \mathrm{H_2O_2} has green color because 
- (a) Oxidation state of iron changed from \mathrm{Fe^{III}} to \mathrm{Fe^{IV}}
- (b) Porphyrin ring is oxidized by one electron
- (c) \pi - \pi^* transition appears in the visible region
- (d) \mathrm{Fe^{IV}} is coordinated with anionic tyrosinate ligand in axial position.
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Answer: (a)
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Q41 · 2012 · 2 marks
The oxidation state of iron in met-hemoglobin is
- (a) Three
- (b) Two
- (c) Four
- (d) Zero
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Answer: (a)
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Q42 · 2012 · 2 marks
The changes (from A-D given below) which occur when \mathrm{O}_{2} binds to hemerythrin are
- (a) One iron atoms is oxidized B and C
- (b) Both the iron atoms are oxidized B and D
- (c) \mathbf{O}_{\mathbf{2}} binds to one iron atom and is also hydrogen bonded. A and D
- (d) \mathbf{O}_{\mathbf{2}} binds to both the iron atoms and is also hydrogen bonded. A and C . Correct answer is (a).
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Answer: (a)
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Q43 · June 2012 · 2 marks
The changes (from A-D given below) which occur when \mathrm{O}_{2} binds to hemerythrin are
- (a) One iron atoms is oxidized B and C
- (b) Both the iron atoms are oxidized B and D
- (c) \mathrm{O}_{2} binds to one iron atom and is also hydrogen bonded. A and D
- (d) \mathrm{O}_{2} binds to both the iron atoms and is also hydrogen bonded. A and C
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Answer: (a)
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Q44 · 2012 · 2 marks
The correct set of the biologically essential elements is,
- (a) Fe, Mo, Cu, Zn
- (b) Fe, Cu, Co, Ru
- (c) Cu, Mn, Zn, Ag
- (d) Fe, Ru, Zn, Mg
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Answer: (a)
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Q45 · 2012 · 2 marks
Based on the behaviour of the metalloenzymes, consider the following statements
- (a) In the enzymes, the zinc activates \mathrm{O}_{2}, to form peroxide species. A and B
- (b) In the enzymes, the zinc activates \mathrm{H}_{2} \mathrm{O} and provides a zinc boud hydroxide. B and C
- (c) In the oxidases, the iron activates \mathrm{O}_{2}, to break the bonding between the two oxygens C and D
- (d) Zinc ion acts as a nucleophile and attacks at the peptide carbonyl The set of correct statements is, A and D
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Answer: (b)
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Q46 · 2012 · 2 marks
\mathrm{Fe}^{+2}-porphyrins fail to exhibit reversible oxygen transport and cannot differentiate CO from \mathrm{O}_{2}. However, the hemoglobin is free from both these pit falls. Among the following
- (a) \mathrm{Fe}^{+2}-porphyrins undergo \mu-oxodimer formation and the same is prevented in case of the hemoglobin.
- (b) \mathrm{Fe}-\mathrm{CO} bond strength is much low in case of hemoglobin when compared to the \mathrm{Fe}^{+2} porphyrins.
- (c) While \mathrm{Fe}-\mathrm{CO} is linear, \mathrm{Fe}-\mathrm{O}_{2} is bent and is recognized by hemoglobin
- (d) The interlinked four monomeric units in the hemoglobin are responsible to overcome the pitfalls.
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Answer: (b)
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Q47 · 2011 · 2 marks
Carboxypeptidase contains:
- (a) \mathrm{Zn} (II) and hydrolyses \mathrm{CO}_{2}
- (b) \mathrm{Zn} (II) and hydrolyses peptide bonds.
- (c) \mathrm{Mg} (II) and hydrolyses \mathrm{CO}_{2}
- (d) \mathrm{Mg} (II) and hydrolyses peptide bonds.
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Answer: (b)
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Q48 · 2011 · 2 marks
Superoxide dismutase contains the metal ions
- (a) Zn (II) and Ni(II)
- (b) Cu(II) and Zn(II)
- (c) Ni (II) and Co(III)
- (d) Cu (II) and Fe(III)
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Answer: (b)
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Q49 · 2011-2020 · 2 marks
Under physiological condition, oxygen is binding to deoxyhemoglobin and deoxymyoglobin, the binding curve and its pH dependence, respectively, are
- (a) Sigmoidal and pH dependent; hyperbolic and pH independent
- (b) Hyperbolic and pH independent:sigmoidal and pH dependent
- (c) Sigmoidal and pH independent;hyperbolic and pH dependent
- (d) Hyperbolic and pH dependent:sigmoidal and pH independent
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Answer: (a)
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Q50 · 2011 · 2 marks
The ligand system present in vitamin B_{12} is:
- (a) Porphyrin
- (b) Corrin
- (c) Phthalocyanine
- (d) Crown ether
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Answer: (b)
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Q51 · Dec 2011 · 2 marks
Superoxide dismutase contains the metal ions
- (a) Zn (II) and Ni(II)
- (b) Cu(II) and Zn(II)
- (c) Ni (II) and Co(III)
- (d) Cu (II) and Fe (III)
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Answer: (b)
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Q52 · 2011 · 2 marks
Among the following drugs, the anticancer agents is:
- (a) captopril
- (b) chloroquine
- (c) camptothecin
- (d) ranitidine
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Answer: (c)
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Q53 · 2011 · 2 marks
The reduction of nitrogen to ammonia, carried out by the enzyme nitrogenase, needs,
- (a) 2 electrons
- (b) 4 electrons
- (c) 6 electrons
- (d) 8 elecrons
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Answer: (d)
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Q54 · 2011 · 2 marks
A metal ion that replace manganese (II) ion in mangano-proteins without changing its function, is
- (a) Fe (II)
- (b) Zn (II)
- (c) Mg (II)
- (d) Cu (II)
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Answer: (c)
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Q55 · Dec 2011 · 2 marks
In the bacterial rubredoxin, the number of iron atoms, sulfur bridges and cysteine ligands are - (a) 4 4 4
- (b) 2 2 4
- (c) 2 2 2
- (d) 1 0 4 CSIR JUNE 2012
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Answer: (d)
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