GATE 2003 PAPER

BIOCHEMISTRY

1. Which amino acid residue is most likely to be found in the interior of a water soluble globular protein?

(A) Ser

(B) Arg

(C) Val

(D) Asp

2. Of the peptide sequences given below, which one is the digestive enzyme trypsin most likely to cleave?

(A) - - - Val – Lys – Pro – Met - - -

(B) - - - Arg – Val – Phe – Tyr - - -

(C) - - - Trp – Asp – Gln – Pro - - -

(D) - - - Glu – Gly – Trp – Gly - - -

3. Which pair of amino acids will have the highest absorbance at 280 nm? (Assume equimolar concentrations)

(A) Thr & His

(B) Phe & Pro

(C) Trp & Tyr

(D) Phe & His

4. Which one of the following statements about protein secondary structure is correct?

(A) An a- helix is primarily stabilized by ionic interactions between the side chains of the amino acids

(B) b- sheets exist only in antiparallel form

(C) b- turns often contains praline

(D) An a- helix can be composed of more than one polypeptide chain

5. The enzymes where catalysis involves transfer of electrons are named as

(A) Isomerases

(B) Transferases

(C) Oxidoreductases

(D) Lyases

6. Vitamin D is derived from which of the following precursors by the action of UV light?

(A) 7- Dehydrocholesterol

(B) Lanosterol

(C) Glycocholate

(D) Squalene epoxide

7. The molecular defect in familial hypercholesterolemia is due to the lack of functional

(A) VLDL receptor

(B) IDL receptor

(C) LDL receptor

(D) HDL receptor

8. Alcaptonuria is an inborn error in metabolism, transmitted as a single recessive Mendelian trait where the enzyme that is absent is

(A) Phenylalanine hydroxylase

(B) Ornithine decarboxylase

(C) Adenosine deaminase

(D) Homogentisate oxidase

9. The prokaryotic RNA polymerase holoenzyme has the subunit structure

(A) a₂bb’s

(B) s₂b₂s

(C) a₂b₂

(D) a₂bb’

10. Given below are four enzymatic reactions involved in glycolysis. In which of the following steps is ATP generated?

(A) 2- Phosphoglycerate to Phosphoenol pyruvate

(B) Glucose – 6 – phosphate to Fructose – 6 – phosphate

(C) Phosphoenol pyruvate to pyruvate

(D) Glyceraldehyde – 3 – phosphate to 1, 3 – Bisphosphoglycerate

Q. 11 – 30 carry two marks each

11. The correct decreasing order of permeability through a lipid bilayer of the molecules/ions Isoleucine, Tyrosine, O₂ and Na⁺ is

(A) O₂>Na⁺>Isoleucine>Tyrosine

(B) O₂> Isoleucine>Tyrosine >Na⁺

(C) Isoleucine>Tyrosine >O₂> Na⁺

(D) Isoleucine>Tyrosine> Na⁺> O₂

12. for the reaction

Fructose–6–phosphate + P_i D Fructose 1, 6-bisphosphate + H₂O

The equilibrium constant at pH 7 and 300K is 10^-3 . the standard free energy change (in kcal per mole) for the reaction is approximately equal to: (R = 2 cal deg^-1 mol^-1)

(A) 4.1

(B) -4.1

(C) 2.2

(D) -2.2

13. Of the four statements given below only one is correct. Pick the correct one

(A) Progesterone is synthesized in the corpus luteum and it prepares the uterine lining for egg implantation and maintenance of pregnancy

(B) Progesterone is synthesized in the ovary and is responsible for female secondary sex characters

(C) Progesterone is synthesized in the adrenal cortex and promotes gluconeogenesis and glycogen formation

(D) Progesterone is synthesized in testis and is responsible for secondary sex characters

14. Which one of the following statement about lipoproteins is true?

(A) Molecular mass of lipoproteins is directly proportional to their destiny

(B) The percent protein content in lipoproteins increases with molecular mass

(C) Density of the lipoproteins decreases with increase in protein content

(D) Molecular mass of lipoproteins is inversely proportionally to their density

15. Choose the correct common sequence motif of Zn finger proteins from the choices given below. X stands for any amino acid

(A) X₃ – Cys – X_2-4 – Cys – X_1-2 – His – X_3-4 – His – X₄

(B) X₃ – Cys – Cys – X_2-4 – His – His – X₄

(C) X₃ – Cys – Cys – His – His – X₄

(D) X₃ – Cys – X_2-4 – His – X_1-2 – His – X_3-4 – Cys – X₄

16. Pick the correct statement

(A) in O- linked glycosylation, sugars are attached to the protein via O- glycosidic bonds to the carboxyl groups of Asp and Glu

(B) In O – linked glycosylation, performed oligosaccharides are attached to the relevant protein

(C) In O – linked glycosylation, N – acetylaglactosamine is added via O – glycosidic bonds to the OH groups of Ser and Thr after which other sugars are added sequentially

(D) O – linked glycosylation is inhibited by the passage of the newly synthesized protein through the glogi complex

17. Which of the following statements is NOT true with regard to photosynthesis?

(A) The dark reactions use NADPH and ATP to drive the synthesis of carbohydrate from CO₂ and H₂O

(B) The principle photoreceptor, chlorophyll is derived biosynthetically from propotoporphyrin IX

(C) Photosystem II (PSII) generates a strong reductant capable of reducing NADP⁺

(D) The components involved in the electron transport from H₂Oto NADPH are largely organized into three thylakoid membrane – bound particles

18. In the adjoining Ramachandran diagram, which type of secondary structure do the regions marked X, Y and Z psi180 represent?

(A) X: right handed a-helix, Y: left handed a-helix, Z: b-sheet

(B) X: left handed a-helix, Y: right handed a-helix, Z: b-sheet

(C) X: b-sheet, Y: right handed a-helix, Z: left handed a-helix

(D) X: b-sheet, Y: left handed a-helix, Z: right handed a-helix

19. The RNase A catalyzed hydrolysis of tRNA follows a two – steps process with the intermediate formation of a 2’, 3’ – cyclic nucleotide. In these steps

(A) His 12 acts as a general base in the transphosphorylation step abstracting a proton from RNA 2’ – OH group.

(B) His 119 acts as a general base in the transphosphorylation step abstracting a proton from RNA 2’ – OH group.

(C) The 2’, 3’ – cyclic intermediate is hydrolyzed when His 12 acts as a general base

(D) His 12 acting as a general acid in the transphosphorylation step promotes bond scission by protonation the leaving group

20. Shown below is the autoradiogram of an electrophoresis gel obtained during the sequencing a single stranded DNA by Sanger’s method.

(A) 3’ AGTCGAGCT 5’

(B) 5’ TCAGCTCGA 3’

(C) 3’ TCAGCTCGA 5’

(D) 5’ AGTCGAGCT 3’

21. In an antigen antibody interaction, in the zone of equivalence, the isolated antigen IgG complex was found to be in the molar ratio of antigen: IgG, 2:1. The number of epitope (s) present on the antigen is

(A) 1

(B) 2

(C) 4

(D) 10

22. Class switching occurs in a B cell to produce IgG from IgM. Which one of the following conclusions is correct?

(A) Specificity of the IgG and IgM are different from each other

(B) Specificity of the IgG is the same as IgM

(C) The molecular weight of the new antibody is the same as the old one

(D) The valency of the new antibody is the same as the old one

23. Two types of IgMs are produced by the same B cell, one that is secreted and the other that can bind to the membrane. Which one of the following statements is correct?

(A) These two antibodies are coded by altogether two different genes.

(B) The membrane anchor residues are added to the protein by post-translational modification.

(C) The two different proteins associate, one of which provides the membrane anchor

(D) The proteins are produced by alternate splicing of its primary transcript.

24. During DNA replication, short RNA primers are synthesized which are then extended by DNA polymerase. These RNA primers in prokaryotes are removed by the enzyme

(A) Primase

(B) RNase H

(C) DNA polymerase I

(D) DNA polymerase III

25. A new antibiotic was discovered which strongly inhibited mRNA precursor transcripts and _snRNA transcripts. This antibiotic was predicted to be an inhibitor of

(A) RNA polymerase I

(B) RNA polymerase II

(C) RNA polymerase III

(D) Helicase

26. Suppose [4-¹⁴C] Oxaloacetate is fed to mitochondria. After one turn of the Citric Acid Cycle, which carbon (s) of succinate would be labeled?

(A) None

(B) Equally distributed between C-1 and C-4

(C) Equally distributed between C-2 and C-3

(D) C-4

27. Two restriction enzymes A and B have eight and four base pairs as their recognition sites respectively. The ratio of the number of fragments that they will generate on restriction digestion of a genomic DNA of E.coli is approximately

(A) 4:8 (B) 8:4 (C) 1:64 (D) 1:256

28. A solution of tryptophan has an absorbance at 280 nm of 0.54 in a 0.5 cm path length cuvette. Given the absorbance coefficient (e) for tryptophan is 5.4´10³M^-1cm^-1, the concentration of the solution is

(A) 0.2mM (B) 20mM (C) 1´10^-3 M (D) 0.1mM

29. From the data given below, identify the protein pair that would (A) give the least mobility band on a sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS – PAGE) experiment and (B) elute last on an anion exchange e.g., DEAE column respectively

Protein	pI	Subunit M.W.	Native M.W.
A	9	10,000	20,000
B	8	35,000	35,000
C	6	15,000	90,000
D	5	20,000	80,000
E	3	30,000	30,000

(A) (A) Protein C (B) Protein A (B) (A) Protein A (B) Protein E

(C) (A) Protein B (B) Protein E (D) (A) Protein B (B) Protein A

30. The graph shows a Lineweaver – Burke plot for an enzyme catalyzed reaction

Which of the following statements is correct?

(A) The V_max is 5mmol/min and with competitive inhibition V_max remains unchanged

(B) K_m is 2mmol/min and with competitive inhibition both K_m and V_max decrease

(C) K_m is 0.5mM and with competitive inhibition V_max increases but K_m remains unchanged

(D) K_m is 2.0mM and with competitive inhibition K_m increases but V_max remains unchanged

Solutions

1. (C) 2. (B) 3. (C) 4. (C) 5. (C) 6. (A)

7. (C) 8. (D) 9. (A) 10. (C) 11. (C) 12. (A)

13. (A) 14. (B) 15. (C) 16. (C) 17. (C) 18. (C)

19. (A) 20. (A) 21. (A) 22. (B) 23. (D) 24. (B)

25. (B) 26. (A) 27. (D) 28. (A) 29. (B) 30. (D)

CHEMISTRY

[Useful data: Planck’s constant, h=6.63 ´ 10^-34 Js; Mass of electron = 9.1 ´ 10^-31 kg; Rydberg constant = 109677; p = 3.142]

Q.1 – 10 carry one mark each

1. In ice, each oxygen atom of water molecule is

(A) Bonded only covalently to two hydrogen atoms

(B) Bonded covalently to two hydrogen atoms and hydrogen-bonded to two other hydrogen atoms

(C) Hydrogen-bonded to four hydrogen atoms

(D) Bonded only covalently to four hydrogen atoms

2. I₂ exists in the solid form under normal temperature and pressure. The principle intermolecular forces holding together iodine molecules in solid is

(A) Covalent

(B) Metallic

(C) Ionic

(D) van der Waals

3. Burning of phosphorus in the presence of air produces a highly hygroscopic white compound, which reacts with water to yield?

(A) H₃PO₄

(B) H₃PO₂

(C) H₄P₂O₇

(D) H₄P₂0₅

4. The minimum uncertainty in the speed of an electron in a one dimensional box of length 10^-10 m is

(A) 580 m/s

(B) 580 km/s

(C) 1160 km/s

(D) 5800 km/s

5. Which one of the following explains the origin of colligative properties correctly?

(A) Increase of the chemical potential of the liquid solvent due to added solute

(B) Reduction of the chemical potential of the liquid solvent due to added solute

(C) Influence of the solute on the chemical potential of the solvent vapour

(D) Influence of the solute on the chemical potential of the solid vapour

6. For a zero order reaction, A à P, if the initial concentration of species A is [A]_o, then t_1/2 can be expressed as

(A) [A]_o/k

(B) 1 / k

(C) 2[A]_o/k

(D) [A]_o/2k

7. Which one of the following compounds is most acidic?

(A) Protonated methanol

(B) Protonated methylamine

(C) Acetic acid

(D) Methanol

8. For a compound to be aromatic, how many p electrons must be in the p cloud?

(A) An even number of pairs

(B) An odd number

(C) An even number

(D) An odd number of pairs

9. Which one of the following alkyl halides would be the most stable in water?

(A) Cyclopropenyl bromide

(B) Cyclopentadienyl bromide

(C) Cylopropyl bromide

(D) Bromobenzene

10. What starting materials must be used in order to have a 1, 4 – cyclohexadiene to be the product of Diels Alder reaction?

(A) A conjugated diene and an alkene

(B) A conjugated diene and an alkyne

(C) A 1, 4 – diene and alkyne

(D) A 1, 2 – diene and an alkyne

Q.11 – 30 carry two marks each

11. The single – bond length between carbon and the elements viz., carbon, nitrogen, oxygen and fluorine follow the order C-C>C-N>C-O>C-F. This trend is due to

(A) Increase in electro negativity

(B) Increase in bond polarity

(C) Increase in atomic weight/

(D) Decrease in atomic size

12. by applying the VSEPR model on the XeF₄ molecule, which one the following statements is true?

(A) Has four bonding pairs and a lone pair

(B) Has octahedral geometry and square planar shape

(C) Has square planar geometry and octahedral shape

(D) Has tetrahedral geometry and tetrahedral shape

13. Which one of the following statements is NOT true for borazine and benzene?

(A) They are isoelectronic

(B) Both are aromatic

(C) Both undergo addition reactions

(D) Both undergo substitution reactions

14. The action of NH₃ on S₂Cl₂ produces a thermo chromic crystalline compound, whose chemical formula is

(A) S₂H₃Cl (B) S₄H₃Cl (C) S₂N₂ (D) S₄N₄

15. The oxidation state of Fe and S in Na₂ [Fe (CO) _4Cl2] and K₂S₂O₈ respectively are

(A) 0 and +5 (B) +2 and +7 (C) +4 and +5 (D) 0 and+4

16. The structure of Ni (CO) ₄ is

(A) square planar

(B) Trigonal pyramidal

(C) Tetrahedral

(D) Distorted octahedral

17. The reaction of CuCo₃ with acetic acid produces a blue crystalline compound with its magnetic moment (m_eff) being » 1.4 B.M./Cu. The compound is

(A) Cu (CH₃COO)₂.2H₂O

(B) Cu₂CO₃ (CH₃COO)₂.2H₂O

(C) Cu(CH₃COO)₂

(D) Cu₂(CH₃COO)₂. 2H₂O

18. The limiting ionic conductivity of Mg²⁺ and Cl^- in H₂O at 298 K is 10.60 and 7.635 mS m² mol^‑, respectively. The limiting molar conductivity (in mS m² mol^-1) of MgCl₂ in H₂O at 298 K is

(A) 18.235

(B) 25.870

(C) 28.835

(D) 60.893

19. The longest wavelength transition in the Balmer series of atomic hydrogen is

(A) 656.5 nm

(B) 6564.7 nm

(C) 15233 nm

(D) 65647 nm

20. In a liquid vapour phase boundary, a plot of ln vapour pressure against the reciprocal of temperature would yield as slope

(A) D_vap H/R

(B) - D_vap H/R

(C) D_vap H/D_vap V

(D) D_vap H/R²

21. For a first order reaction, A à P, the time required to complete 80% of the reaction is

(A) ln 1.25 /k

(B) ln 8 /k

(C) ln 5 /k

(D) ln 80 /k

22. If the molar enthalpy and entropy of fusion of water are 6.01 kJ / mol and 22.0 J / mol K, respectively, the DG for the melting of ice at 10 ° C is

(A) – 6220 kJ / mol

(B) – 214 kJ / mol

(C) – 5.79 kJ / mol

(D) – 0.22 kJ / mol

23. When steady state approximation is applied in enzyme kinetics, which one of the following statements is correct with regard to the concentration of the enzyme substrate complex, [ES]

(A) d[ES]/dt = 0

(B) d[ES]/dt = constant

(C) [ES] = 0

(D) d[ES]/dt = infinity

24. The wavelength possessed by a cricket ball of mass 1 kg, traveling with a velocity of 40 m/s is

(A) 1.66 ´ 10^-38 m

(B) 1.66 ´ 10^-35 m

(C) 2.65 ´ 10^-32 m

(D) 1.66 ´ 10³³ m

25. Which one of the following reaction sequence will convert toluene to p-chlorobenzoic acid?

(A) (i) Cl2 / light, (ii) hot KMnO4 / H+

(B) (i) Hot KMnO₄ / H⁺, (ii) Cl₂ / FeCl₃

(C) (i) Cl₂ / FeCl₃, (ii) hot KMnO₄ / H⁺

(D) (i) N- Chorosuccinimide, (ii) hot KMnO₄ / H⁺

26. For 2,3 – dibromobutane, which one of the following statement is true?

(A) (2S, 3S) and (2R, 3S) is a pair of diastereomers; (2R, 3R) and (2S, 3S) is a pair of enantiomers

(B) (2S, 3S) and (2R, 3S) is a pair of diastereomers; (2R, 3R) and (2S, 3R) is a pair of enantiomers

(C) (2R, 3R) and (2S, 3S) is a pair of diastereomers; (2S, 3S) and (2R, 3S) is a pair of enantiomers

(D) (2R, 3R) and (2S, 3S) is a pair of diastereomers; (2R, 3R) and (2S, 3S) is a pair of enantiomers

27. When trans-1-bromo-2-methylcyclohexane reacts with methoxide ion, what products are formed under S_N2 and S_N1 conditions?

(A) S_N2 and S_N1 both form cis and trans-1-methoxy-2-methylcyclohexane

(B) S_N2 forms cis-1-methoxy-2-methylcyclohexane and S_N1 forms cis and trans-1-methoxy-2-methylcyclohexane

(C) S_N2 forms cis-1-methoxy-2-methylcyclohexane and S_N1 forms 1-methoxy-1-methylcyclohexane

(D) S_N2 forms cis-1-methoxy-2-methylcyclohexane and S_N1 forms trans-1-methoxy-2-methylcyclohexane

28. What product (s) is (are) formed when HBr is eliminated form (2S, 3S)-2-bromo-3-phenylbutane in an E2 reaction?

(A) (Z)-2-phenyl-2-butene

(B) (Z) and (E)-2-phenyl-2-butene

(C) (E)-2-phenyl-2-butene

(D) (E)-3-methyl-3-phenyl-1-butene

29. The major product that would be formed in a Diels Alder reaction between (E)-penta-1, 3-diene(trans-1-methyl-1, 4-butadiene) and methyl acrylate is

(A) 1, 2-product (ortho) with Me and CO₂Me cis to each other

(B) 1, 2-product (ortho) with Me and CO₂Me trans to each other

(C) 1, 3-product (meta) with Me and CO₂Me cis to each other

(D) 1, 3-product (meta) with Me and CO₂Me trans to each other

30. How many resonance structure contributors can be written for the carbocation intermediate formed when phenol undergoes electrophilic substitution in the ortho, meta and para positions?

(A) ortho:3, meta:3 and para:4

(B) ortho:3, meta:3 and para:3

(C) ortho:4, meta:3 and para:4

(D) ortho:3, meta:4 and para:3

Solutions

1. (B) 2. (D) 3. (A) 4. (B) 5. (B) 6. (D)

7. (C) 8. (C) 9. (C) 10. (C) 11. (B) 12. (B)

13. (B) 14. (D) 15. (B) 16. (C) 17. (D) 18. (B)

19. (A) 20. (B) 21. (C) 22. (B) 23. (A) 24. (B)

25. (C) 26. (A) 27. (B) 28. (C) 29. (B) 30. (C)

MICROBIOLOGY

Q.1 – 10 carry one mark each

1. Mycoplasmas are different from other prokaryotes by

(A) Presence of chitin in cell walls

(B) Presence of murein in cell walls

(C) Presence of proteins in cell walls

(D) Absence of ell wall itself

2. Selective media facilitate growth of only one kind of organism. Saboraud’s medium is used to selectively isolate

(A) Coliform bacteria (B) Gram positive bacteria

(C) Yeasts (D) Acid fast organisms

3. The cell walls of Gram positive bacteria contain two modified sugars, viz., N–acetylglucosamine (NAG) and

N–acetylmuramic acid (NAM). They are covalently linked by

(A) a-1, 4-glycosidic bond (B) b-1, 6-glycosidic bond

(C) a-1, 6-glycosidic bond (D) b-1, 4-glycosidic bond

4. The metal ion required for the enzymatic activities of nitrogenase and nitrate reductase is

(A) Molybdenum (B) Iron (C) Copper (D) Zinc

5. DNA gyrase is inhibited by

(A) Tetracyclin (B) Nalidixic acid

(C) Aurintricarboxylic acid (D) Cephalosporin

6. Surface receptor (IgA) on the target cell is the site of binding of

(A) Hepatitis B Virus (B) HIV

(C) Rabies (D) Influenza A, B viruses

7. In anoxygenic photosynthesis, the green and purple bacteria do not use the following one as electron source

(A) H₂O (B) H₂ (C) H₂S (D) S (elemental sulphur)

8. Macrophages are professional antigen-presenting cells. The protein molecule through which they present antigen in humans is

(A) Actin (B) Interleukin (C) HLA (D) CD8

9. The organism used for production of ‘BT’ bioinseticide belongs to the genus

(A) Borrelia (B) Bacillus

(C) Bordetella (D) Blastobacter

10. The bacteriophage with a single stranded circular DNA, as genome is

(A) T4phage (B) l phage (C) MS2 (D) f´174

Q.11 – 30 carry two marks each

11. A gram negative rod showed on EMB agar colonies with dark centre and greenish metallic sheen. The organism is

(A) Salmonella (B) Shigella (C) E.coli (D) Pseudomonas

12. Two antibiotics have different sites of action in a bacterial cell. The frequency of occurrence of resistance to these antibiotics used singly are 10^-5 and 10^-6, respectively. When the antibiotics are used in combination the frequency of occurrence of resistance to both antibiotics are

(A) 10^-5 (B) 10^-6 (C) 10^-30 (D) 10^-11

13. Species of pencillium. Streptomyces and bacteria have been sources of the following group of important biomedical industrial product(s)

(A) Methane and other gases (B) Steroids

(C) Antibiotics (D) Insulin, Interferon

14. In the normal human being the concentration(s) of various antibiotics in the serum is are in the order

(A) IgM>IgA>IgG>IgE (B) IgG>IgA>IgM>IgE

(C) IgE>IgG>IgM>IgA (D) IgA>IgM>IgE>IgG

15. The mild Streptococci produce acetoin that gets spontaneously oxidized yielding a flavoring agent (responsible for aroma of butter) is

(A) Acetone (B) Acetyl CoA

(C) Butyric acid (D) Diacetyl

16. Syntrophy is the phenomenon where

(A) One microorganism degrades a substance and uses it

(B) One microorganism degrades the substance and the other microorganism uses it

(C) Two or more microorganisms cooperate to degrade a substance which neither can do alone

(D) Two or more organisms can independently degrade the substance but one inhibits the other from doing so

17. Association coefficient S_AB is given by the expression: 2N_AB/(N_A+N_B)

Organism A UCACUUCUG–3’ PO₄

Organism B UAUCUAAUG–3’ PO₄

S_AB value for organisms 1 and 2 is

(A) 0.25 (B) 0.50 (C) 0.75 (D) 1.00

18. ATP synthetase is a multifunctional enzyme with a subunit constitution of a₃b₃gde. The pair of constituent subunits taking part in nucleotide binding and catalysis are

(A) a1b1 (B) a2b2 (C) a3b3 (D) gd

19. The release of terminal D–ala from Park peptide during cross–linking, is catalyzed by

(A) Carboxypeptidase (B) protease

(C) aminopeptidase (D) transpetidase

20. Which one the following sequences has helped in identifying Eukaryotes, Eubacteria and Archeabacterial cell types?

(A) Signature sequence (B) signal sequence

(C) shine–Dalgarno sequence (D) aminoacid sequence

21. In photo reactivation of UV exposed cells the enzymes which synthesizes daughter DNA strand at 70°C and also proof –reads is

(A) Klenow fragment (B) DNA pol I(E.coli)

(C) Pfu pol (Pyrococcus furiosus) (D) Taq polymerase

22. Lequconostoc mesenteroids when streaded and grown on sucrose medium produces large mucoid colonies. It is due to the synthesis of dextran layer having a chemical structure of

(A) a-glu-b-fru2®6b-fru (B) a-fru-b-glu2®6b-glu

(C) b-fru-a-glu1®6-aglu (D) b-fru-a-glu2®6a-glu

23. Media containing spores and thermolabile constituents are sterilized by

(A) Pasteurization (B) UV irradiation

(C) Dry heat (D) Tyndallization

24. A highly aerobic and metabolically versatile organism used in oil–spill–clearing is

(A) Mycobacterium smegmatis

(B) Azotobacter vinelandii

(C) Pseudomonas cepacia

(D) Leuconostoc mesenteroides

25. Penicillin and lysozyme prevent synthesis and cause lysis, respectively, of cell walls of

(A) Micrococcus lysodeikticus

(B) Escherichia coli

(C) Saccharomyces cerevisiae

(D) Methanobacterium barkeri

26. In Adansonian numerical taxonomy tow organisms (A) and (B) tested positive and / or negative to a battery of tests

Number of test positive in both (A) and (B) = 80

Number of tests positive in (A) only = 6

Number of tests positive in (B) only = 4

Number of tests negative in both (A) and (B) = 10

Similarity coefficient S_J is

(A) 0.88 (B) 0.77 (C) 0.66 (D) 0.55

27. In Calvin cycle, RubisCO incorporates CO₂ into ribulose 1, 5–bisphosphate (1^st 6 carbon compound), which rapidly splits into

(A) Glyceraldehyde-3-P (B) 2, 3-phosphoglyceric acid

(C) 3-Phosphoglycerate (D) 1, 3-diphosphoglycerate

28. A bacterial culture had an initial cell density of 10³cells/ml. In 6 hours the cell density reached 10⁶cells/ml. Given the formula for the number of generations, n = (log₁₀N_t-log₁₀N₀)/0.301 the number of generation (n) the cells have undergone is

(A) 3 (B) 10 (C) 15 (D) 20

29. Zymomonas mobilis metabolises glucose by Entner-Doudoroff pathway. In this pathway dehydratase converts 6-phosphogluconic acid into

(A) phosphogluconic acid

(B) 2-keto-6phosphogluconic acid

(C) 2-keto-6-dexoygluconic acid

(D) 2, keto-3-deoxyphosphogluconic acid

30. When a ‘pseudomonad’ is wet – mounted and observed by microscopy, the motility stops after a few minutes. Motility is restored by adding arginine solution because

(A) Arginine replenishes amino acid pool

(B) Arginine metabolism yields ATP

(C) Arginine gets hydrolyzed to citrulline and ammonia

(D) Arginine metabolism leads to the formation of other amino acids

Solutions

1. (D) 2. (C) 3. (D) 4. (A) 5. (B) 6. (D)

7. (A) 8. (C) 9. (B) 10. (D) 11. (C) 12. (B)

13. (C) 14. (B) 15. (D) 16. (C) 18. (C) 19. (D)

20. (D) 21. (B) 22. (B) 23. (B) 24. (C) 25. (A)

26. (A) 27. (D) 28. (B) 29. (D) 30. (B)