BIOCHEMISTRY
Q. 1-10 carry one mark
1. Which pair of aminoacid residues can interact in the interior of the protein only through Van der Walls forces?
(A) Arg, Thr,
(B) Ser, Thr
(C) Glu, His
(D) Val, Leu
2. Okasaki fragments are joined by the enzyme
(A) RNA polymerase
(B) DNA polymerase
(C) DNA ligase
(D) Reverse transcriptase
3. The biosynthetic reaction in a cell mainly takeplace in
(A) mitochondria
(B) Lysosomes
(C) smooth endoplasmic reticulum
(D) golgi apparatus
4. Colchichin inhibits
(A) DNA replication
(B) Formation of spindle fibres
(C) Condensation of chromosomes
(D) cytokinesis
5. the active form of testosterone is
(A) dihydro testrosterone
(B) dehydro testrosterone
(C) dihydroxy testrosterone
(D) dehydro epiandrosterone
6. the sensitivity of a radio immno assay depends primarily on
(A) Titer of the antibody
(B) Specificity of the antibody
(C) Specific activity of a ligand
(D) Purity of antigen
7. In eukaryotes, introns can be found in transcripts which are the precursors of
(A) mRNA
(B) rRNA
(C) tRNA
(D) all the above
8. Homologous recombination can be employed to generate
(A) Transgenic animals
(B) Gene knock-out aniamals
(C) Site specific mutagenesis
(D) Specific promoter sequence
9. The mode of action of widely used anti cancer drug methotrexate is to inhibit
(A) Dihydrofolate reductase
(B) Dihydrooratate dehydrogenase
(C) Carbomyl phosphate synthase-2
(D) Ribonucleotide reductase
10. For a double stranded DNA which one of the following base ratio will be always equal to one?
(A) (A+T)/ (G+C)
(B) (A+G)/(C+T)
(C) C/T
(D) A/G
Q. 11-26 carry two marks each
11. Activated fatty acyl groups are transported into the mitochondria by
(A) Coenzyme A
(B) Oxaloacetate
(C) Carnitine
(D) Citrate
12. a mixture of cytochrome-C (MW 17.2 KD) are to be separated by polyacrylamide gel electrophoresis. Their isoelectric pH (pI) values are 9.6 and 7.2 respectively. In which direction will each protein migrate at pH 8.5?
(A) Myoglobin will migrate to anode and Cytochrome-C will migrate to cathode
(B) Myoglobin will migrate to cathode and Cytochrome-C will migrate to anode
(C) Both will migrate to anode
(D) Both will migrate to cathode
13. Which one of the following fatty acid will have melting point higher than that of palmatic acid (16 : 0)?
(A) Myristic acid (14 : 0)
(B) Palmitoleic acid (16 : 1)
(C) Oleic acid (18 : 1)
(D) Stearic acid (18 : 0)
14. a diabetes mellitus patient excretes glucose in urine even when kept on carbohydrate free diet. This is because
(A) Fats are catabolised in liver to form glucose
(B) Amino acids are catabolised in liver to form glucose
(C) Increased production of aminoacid
(D) Increased breakdown of glucogen
15. according to second law of thermodynamics, molecules spontaneously moves frm a region of higher concentration to one of lower concentration. However, sodium ions are present at 143 mM outside the cell and 14 mM inside the cell. Yet sodium cannot pass through the plasma membrane. Transport of sodium into the cell is achieved by
(A) Facilitated diffusion
(B) Release of acetyl choline
(C) Release of norepinephrine
(D) Sodium transporter
16. The choice of the enzyme used in elisa depends on
(A) Purity of enzyme
(B) Turn over number
(C) Its absence in the biological sample which is being analysed
(D) Its availability in bulk
17. The T cell antigen receptor
(A) Recognize conformational epitopes on the native molecule
(B) Has Ig life chain
(C) Is made up of heavy chain and 2 microglobulin
(D) Recognizes epitopes on linear peptides associated with MHC determinants
18. The advantage of degeneracy in codons is that
(A) It minimizes the deleterious effect of mutations
(B) It provides more flexibility
(C) It helps to code proteins resistant to proteases
(D) It helps to code proteins of very high molecular weight
19. The pKa ‘s of lysine are given below:
pKa (COOH) = 2.2, pKa (α – NH3) = 9.0, pKa (ε – NH3+) = 10.0
The pI of lysine is
(A) 7.07
(B) 9.50
(C) 6.10
(D) 5.60
20. the molecular weight of a bacterial DNA molecule is 2.64 109 . the average molecular weight of a nucleotide pair is 660. assume that the average protein is madeup of 400 aa residues.what is the maximum number of protens that can be coded by the bacterial DNA molecule?
(A) 20000
(B) 3333
(C) 6667
(D) none of the above
21. The coenzyme involved in the formation of acetyl CoA from pyruvate are
(A) Thiamine pyrophosphate, lipoic acid and FAD
(B) Pyridoxyl phosphate, biotin and FAD
(C) vitamin B – 12, folic acid and vitamin C
(D) NADH, lipoic acid and vitamine E
Common Data Questions
Common Data for Questions 22, 23, 24: A restriction fragment, obtained with a type II endonucleases that recognizes a six base pair site, was subjected to Maxam – Gilbert sequencing with results as shown in the autoradiogram below.
G A+G C C+T
- -
-
-
-
-
- -
-
-
-
- -
-
-
- -
22. The DNA sequence is
(A) 3` CTAGATAGTATAG 5`
(B) 5` CTAGATAGTATAG 3`
(C) 3` GATCTATCATATC 5`
(D) 5` GATCTATCATATC 3`
23. The restriction site is
(A) TAGCTA
ATCGAT’
(B) TAGGTA
ATCCAT’
(C) ATCCAT
TAGGTA’
(D) GATACC
CTATGG’
24. Considering this DNA sequence as a template strand, the sequence of the corresponding mRNA is
(A) 5` CTAGATAGTATAG 3`
(B) 3` GATCTATCATATC 5`
(C) 3` GAUCUAUCAUAUC 5`
(D) 5` CUAGAUAGUAUAG 3`
Common Data for Questions 25, 26: The kinetic data for an enzymatic reaction in the presence and absence of inhibitors are plotted in the following figure.
25. Which line represents the kinetics without inhibitor?
(A) line 1
(B) line 2
(C) line 3
(D) line 4
26. which line represents kinetics of non-competitive inhibition?
(A) line 1
(B) line 2
(C) line 3
(D) line 4
Linked answer questions: Q27a to Q28 carry two marks each
Statement for linked answer questions 27a & 27b: transmission at many synapses in central nervos system is mediated by acetyl choline. Acetyl choline is cleaved to acetate and choline by the enzyme acetyl choline esterases which can be inhibited by diisopropyl phosphofluoridate (DIPF).
27a. the mode of action of DIPF is by
(A) modifying histidine residue
(B) covalently modifying a crucial serine residue
(C) inducing a conformational change in the protein
(D) forming a complex with choline
27b. based on its mode of action, DIPF is used as
(A) A therapeutic agent to treat neuro degenerative diseases
(B) a nerve gas
(C) as an agomst of acetyl choline
(D) a reagent to determine the N- terminal amino acid
Statement for linked answer questions 28a & 28b: the following fragments are isolated on partial hydrolysis of a nonapeptide X
Val-Arg-Pro-Gly, Lys-Phe-Val-Arg, Ala-Gly-Ser-Lys
28a. the correct sequence of X is
(A) Ala-Gly-Ser-Lys-Ala-Pro-Val-Arg-Gly
(B) Val-Arg-Gly-Lys-Phe-Val-Arg-Ala-Pro
(C) Lys-Phe-Val-Arg- Ala-Gly-Ser-Pro-Gly
(D) Ala-Gly-Ser-Lys-Phe-Val-Arg-Pro-Gly
28b. the number of fragments obtained when X is digested with trypsin is
(A) 0
(B) 2
(C) 3
(D) 4
SOLUTIONS
1. (A)
Best possible option is (A)
(A) Arg, Thr – cant’s form H2 bonds easily
(B) Ser, Thr – hydrophilic interactions
(C) Glu, His – Ionic interactions
(D) Val, Leu – hydrophobic interactions
2. (C)
DNA ligase . these enzymes catalyse formationof a phophodiester bond between the 5` phosphate of one strand of DNA and the 3` hydroxyl of another. Most widely used DNA ligase is T4 DNA ligase derived from T4 bacteriophage.
3. (C)
Smooth E.R
4. (B)
Formation of spindle fibres. Colchine inhibits by binding to and preventing the polymerization of tubulin monomers.
5. (A)
The active form of testosterone is converted to dihydro testosterone by enzymes 5α reductase.
6. (C)
RIA is used to detect molecules that cannot be radioactively labeled in virus to a suitable specific activity. There is a competition for antibody binding between a radioactive indicator antigen or ligand and its unlabelled counterpart.
7. (D)
8. (B)
A vector consists of the homologous regions which have complimentary strands of DNA on either side of the targeted gene in the genome. The disrupted gene along with gene coding for antibiotic resistance are included between the homologous regions. Once the vector is introduced into the cell it is incorporated into the genome by homologous recombination.
9. (A)
As it is folic acid analogue.
10. (B)
For a double stranded DNA; every purine must have pyrimidine and viceversa. And the number of purines = pyrimidines.
11. (C)
Activated fatty CoA is exchanged for carnitine by Carnitine –palmitayl transferase I.
12. (B)
Myoglobin will migrate to cathode and cytochrome C will migrate to anode. Cytochrome C is negatively charged above 9.6 hence moves to cathode. Below 9.6 it is positively charged and moves to anode. Myoglobin moves to cathode because it is negatively charged. Above its Pi 7.2
13. (D)
Stearic acid (18:0) 69C Saturated fatty acid
14. (A)
Fats are catabolised in liver to form glucose.
15. (D)
Plasma membrane is less permeable to Na + ions. Import of Na + glucose is carried out by Na – glucose symporter. In the symprter protein Na + bind to the symporter triggering the glucose to bind to another site .binding of both the molecules (Glucose) and (Na +) cause a conformational change in the symporter thereby releasing the molecules within the cell.
16. (C)
Its absence in the biological sample which is being analyzed. Choice of the enzyme used in ELISA depends on
(i) Stability of the enzyme
(ii) High specific activity
(iii) Substrate turnover number
(iv) Inexpensive
(v) Absence of antigen or anti – serum preparation to be used in serologic tests.
17. (D)
Recognizes epitopes on linear peptide associated with MHC determinants.
18. (A)
It minimizes the deleterious effects of mutations.
19. (B)
pI of lysine = Average pf pKa (α – NH3+) + (pKa [εNH3+])
=(9.0+10.0)/2
= 19/2
=9.5
20. (B)
21. (A) Thiamine pyrophosphate, Lipoic acid and FAD
22. (B)
23. (A)
It is a palindromic sequence TT , TAAT
24. (C)
25. (A)
26. (C)
27a. (B)
27b. (B)
28a. (D)
28b. (C)
CHEMISTRY
[Useful data: F = 96485 C mol-1 ; R = 8.314 J K-1 mol-1; Atomic number: Co.27]
Q.1 – Q.10 Carry One Mar Each
1. Elements exhibiting +2 oxidation state in their compounds is:
(A) Zn and P (B) Ca and Al
(C) Al and P (D) Zn and Ca
2. The paramagnetic species is:
(A) Na2 (B) NO+ (C) CN (D) CO
3. Hydride that readily liberates hydrogen gas on reaction with water is:
(A) NaBH4 (B) CaH2 (C) SiH4 (D) NH3
4. Which one of the following is aromatic?
(A)
(B)
(C)
(D)
5. Identify the product of the following reaction
6. which one of the following is more acidic?
(A)Butanoic acid (B) 3- Chlorobutanoic acid
(C) 2 - Chlorobutanoic acid (D) 4 - Chlorobutanoic acid
7. Total number of sterioisomers possible in CH3 – CH(Ph)- CH = CHCH3 is:
(A) 1 (B) 2 (C) 3 (D) 4
8. The standard EMF of the cell, set up from the reaction 2Cu+(aq) Cu(s) + Cu2+ (aq) is 0.36 V at 298 K. the standard Gibbs free energy in kj/mol for this reaction is:
(A) -34.73 (B) -69.46 (C) -3473 (D) -6946
9. Heisenberg’s uncertainty principle is expressed as:
(A) Δp Δx ≥ h/2 п (B) Δp Δx ≤ h/4 п
(C) Δp Δx ≤ h/2 п (D) Δp Δx ≥ h/4 п
10. for the reaction, C6H1206 (s) + 602 (g) 6 CO2 (g) + 6H2O(l), ΔU = -2810 kj/mol. ΔH in kj/mol is:
(A) 845 (B) -890 (C) -2810 (D) -2864
11. which one the following is a repeating unit of silicone?
(A) Si(CH3)4 (B) Si(CH3)2O (C) SiO2 (D) Si(OCH3)4
12. the order of lattice energy of NaX is NaI <>
(A) ionic radii (B) electronegativity
(C) atomic radii (D) electron affinity
13. Among BF3, CF4, PF3, and OF2, the molecules that are expected to have a zero dipole moment is:
(A) OF2 and CF4 (B) BF3 and PF3
(C) OF2 and PF3 (D) BF3 and CF4
14. Air oxidation of sodium metal produces a hygroscopic compound ‘X’, which reacts with CO2 to produce ‘Y’. X and Y respectively are:
(A) Na2O2 and Na2CO3 (B) Na2O and NaHCO3
(C) NaOH and Na2CO3 (D) Na2O and Na2CO3
15. The product reaction of HNO3 with P4 and P4O10 respectively are:
(A) N2O3 and N2O5 (B) N2O5 and NO2
(C) NaOH and N2O5 (D) NO and NO2
16. Identify the product for the following Diels – Alder reaction.
(A)
(B)
(C)
(D)
17. Major product of reaction given below is:
(A)
(B)
(C)
(D)
18. 0.050mol of Ar initially at 25C, expands adiabatically and reversibly from 0.50L to 1.00L(Cv,m for Ar is 12.48J/Kmol). The work done in this process is:
(A) 117J (B) – 69J (C) – 138J (D) – 1378J
19. Efficiency of a reversible cyclic heat engine working between Tc and Th is:
(A) – Tc/Th (B) (Tc – Th)/Th
(C) (Th – Tc)/Th (D) Tc/Th
20. To prepare one liter of an acetate buffer of 0.1 ionic strength and pH5, at 25C, the moles of sodium acetate and acetic acid (dissociation constant = 2.69 10 –5) to be added respectively are:
(A) 0.1 and 0.0372 (B) 0.0372 and 0.1
(C) 0.01 and 0.372 (D) 0.372 and 0.01
21. The EMF of the cell {Pt, H2 (atm)| HCl (aq)| AgCl, Ag}is 0.332V and the EMF of AgCl | Ag electrode is 0.277V. pH of the solution is:
(A) 0.926 (B) 1.03 (C) 3.26 (D) 5.61
22. In a saturated aqueous solution of CaF2, the concentrations of Ca2+ and F– are 3.310–4M and 6.710–4M, respectively. On adding NaF to this solution, if the concentration of Ca2+ changes to 1.510–4M, then concentration of F– will be
(A) 1.010–8 (B) 1.010–6
(C) 1.010–4 (D) 1.010–3
Common Data Questions
Common data for Q.23&Q.24: Reaction: A+BProducts
23. When the reaction is first order in A and zero order in B, rate constant is:
(A) {-1/t[A]0}ln ([A]0/[A]t)
(B) (-1/t) ln ([A]0/[A]t)
(C) (1/t)ln([A]0/[A]t)
(D){1/(t[A]0}ln([A]0/[A]t}
24. when the reaction is second order in a and ero order in B, rate constant is:
(A) (1/t) {([A]t - [A]0)/([A]0[A]t)}
(B) (1/t) {(1/[A]t - (1/[A]0}
(C) {1/(t[A]0)}{([A]t - [A]0)/([A]0[A]t)}
(D) {1/(t[A]0)}{(1/[A]t) – (1/[A]0)}
Common data for Q.25 & Q.26: 3,3–dimethyl–1–butane (Me3C – CH=CH2), on reaction with
25. hydrochloric acid produces a halogenated compound as major product. The product is:
(A) Me3C–CH(Cl)–CH3 (B) Me3C–CH2–CH2Cl
(C) Me3C(Cl)–CHMe2 (D) Me3C(Cl)–CH2CH 2CH3
26. Hg(OCOCH3)2 followed by treatment with alkaline NABH4 produces:
(A) Me3C(OH)–CHMe2 (B) Me3C(OH)–CH2CH 2CH3
(C) Me3C–CH2–CH2OH (D) Me3C–CH(OH)–CH3
Linked Answer Questions: Q.27a to Q.28b carry two marks each
Statement for Linked answer question Q. 27a & Q.27b: A pink coloured aqueous solution of CoCl2, changes immediately to blue on adding excess of Cl- ion.
27a. The blue coloured species is:
(A) [CoCl6]3– (B) [CoCl4]2–
(C) [Co(H2O)6]2+ (D) [CoCl4]1–
27b. The d–electron configuration for the blue complex on is:
(A) e3t32 (B) t32ge2g (C) t42ge2g (D) e4t32
Statement for linked answer question Q.28a & Q.28b: Ethylbenzene reacts with,
28a. N – bromosuccinimide to produce compound ‘X’. X is:
28b. ‘X’ on treatment with t–BuOK in butanol provide ‘Y’. The product Y is:
Solutions
1. (D)
2. (C) The species which has unpaired electrons in its outer orbitals
3. (A)
NaBH4 + 4H2O NaOH + H3BO3 + 4H2
4. (B)
5. (A)
6. (D)
7. (B) Cis & trans form of the parent molecule
8. (B)
9. (D)
10. (C) ΔU = Q–W this equation in analogous to ΔH = Q - W
11. (B)
12. (A)
13. (D)
14. (A)
Reactions: (i) 2Na + O2 Na2O2(major) + Na2O(very little)
(ii) Na2O2 + CO2 Na2CO3 + O2
15. (C)
16. (B)
17. (C) The reaction is Claisen condensation
18. (B)
19. (C)
20. (A)
21. (A)
22. (D)
23. (B)
24. (B)
25. (A)
26. (D)
27a. (B)
27b. (B)
28a. (C)
28b. (A)
MICROBIOLOGY
Q. 1-10 carry one mark each
1. the scientists who discovered restriction endonucleases are
(A) Temin and Baltimore
(B) Arber and Smith
(C) Gilbert and Sanger
(D) Lederberg and Tatum
2. The virus responsible for the ‘Severe Acute Respiratory Syndrome’ (SARS) is a
(A) Picornavirus
(B) Coronavirus
(C) Adenovirus
(D) Influenza virus
3. Denitrification process cariedout by a few groups of bacteria reduces nitrate (NO3) to nitrogen (N2) gas. How many electrons per nitrogen atom are transferred to nitrate in this process?
(A) 2
(B) 3
(C) 4
(D) 5
4. metabolic yield of a product by an industrially important microorganism is defined as
(A) gram product formed/gram substrate consumed
(B) gram product formed/gram cells formed
(C) gram product formed/litre of culture broth
(D) gram product formed/(litre.hour)
5. Which of the following features can distinguish Bacteria and Archea?
(A) absence of the membrane-enclosed nucleus
(B) Absence of internal membranous organelles
(C) The type of glyosidic bonds present in the peptidoglycan layer (or its equivalent) of the cell wall
(D) Presence of N-acetyl glucosamine in the peptidoglycan layer (or its equivalent) of the cell wall
6. which of the following feature is not exhibited by green sulphur photosynthetic bacteria
(A) Presence of bacteriochlorophylls
(B) Sulphur deposition outside the cell wall
(C) Oxygenic mode of photosynthesis
(D) Non motile nature of cells
7. The microorganism which obtain energy from the oxidation of inorganic compounds are known as
(A) Photoautotrophs
(B) Chemolithotrophs
(C) Photoelecterotrophs
(D) Chemoorganotrophs
8. Neutrophiles exchange potassium for proton using
(A) Antiport transport system
(B) Symport transport system
(C) ABC transport system
(D) Group translocation
9. Amphotericin B selectively disrupts the cell membrane of fungi because of its high affinity for a compound present in fungal membrane. The name of this compound is
(A) Ergosterol
(B) Mannitol
(C) Miconazole
(D) Clotrimazole
10. Which of the following ‘hepatitis virus’ has DNA genome
(A) Hepatitis A
(B) Hepatitis B
(C) Hepatitis C
(D) Hepatitis E
Q. 11- Q. 26 carry two marks each
11. Which of the following groups of microorganism contains both superoxide dismutase and catalase enzyme for growth?
(A) Obligate aerobes only
(B) Facultative anaerobes only
(C) Strict anaerobes only
(D) Both Obligate aerobes and facultative anaerobes
12. which of the following is not responsible for making bacteria resistant to penicillin action?
(A) Change in the penicillin binding proteins
(B) Inability of penicillin to reach its site of action
(C) Inability to bind 30s ribosomal subunit
(D) Presence of plasmid codng for penicilinase
13. Match the correct combination of the antibiotic and the microorganism producing it
Antibiotic Microorgaism
P. Vancomycin 1. Bacillus subtilis
Q. Bacitracin 2. Cephalosporium acremonium
R. Chloramphenicol 3. Streptomyces orientalis
S. Streptomycin 4. Pencillium chrysogenum
5. Streptomyces venezuelae
6. Streptomyces griseus
(A) (B) (C) (D)
P-3 P-1 P-5 P-6
Q-1 Q-4 Q-3 Q-3
R-5 R-6 R-6 R-5
S-6 S-3 S-4 S-2
14. The pathogenesis associated with Vibrio cholerae infection depends on the colonization of the small intestine by the organism and secretion of an enterotoxin. Which of the following statement related to pathogenecity of cholera is incorrect?
(A) Vibrio cholerae secrets the enterotoxin choleragen
(B) Choleragen consists of A (active) and B (binding) subunit
(C) Choleragen toxin alone cannot reproduce the symptoms of cholera in the absence of Vibrio cholerae
(D) CTX bacteriophage carries the genes of cholera toxin and other virulence factors
15. prior infection of Mycobacterium tuberculosis can be detected by positive tuberculin skin test results. The basis of this test is
(A) anaphylactic hypersensitivity (Type I)
(B) Antibody dependent cytotoxic hypersensitivity (Type II)
(C) Immune complex mediated hypersensitivity (Type III)
(D) Cell mediated or delayed hypersensitity (Type IV)
16. A bacterial culture on being transferred form anaerobic condition of growth drastically reduce the rate of glucose catabolism. This regulatory phenomenon is known as
(A) Tyndallization
(B) Pasteurization
(C) Crabtree effect
(D) Pasteur effect
17. Which of the following statements related to ‘High frequency recombination’ (Hfr) cells is incorrect
(A) Single strand of DNA that enters into recipient F cell contains a piece of the F factor at the leading end followed by the bacterial chromosomes and then by the remainder of the F factor
(B) Most mating results in the transfer of only a portion of donor chromosome because the attachment between the two cells can break
(C) The bacterial genes adjacent to the leading piece of the F factor are least frequently transferred.
(D) The donor cells genes that are transferred vary, since the F plasmid can integrate at several different sites in a bacterial DNA
18. Replication of the positive strand genome of poliovirus requires
(A) Reverse Transcriptase
(B) Virus encoded RNA dependent RNA polymerase
(C) DNA dependent RNA polymerase
(D) DNA polymerase
19. Which of the following statement is incorrect about bacteriophage λ is incorrect?
(A) It initially produces two proteins; one acts as an inhibitor of λ repressor synthesis and the other acts as a terminator for transcription
(B) It maintains its lysogenic state in the absence of an inducer
(C) In switching from the lysogenic to the lytic phase, it turns off the synthesis of λ repressor because cro protein binds to λ operator OR3
(D) It forms N and Q gene products which act as positive regulatory proteins leading to the sequential production of λ encoded proteins
20. while evaluating the effectiveness of a disinfectant (X) against Salmonella typhi by the ‘Phenol- Coefficient Method’ the following data were obtained
Subculture tubes
Dilution 5 min 10 min 15 min
Disinfectant (X) 1 : 50 0 0 0
1 : 100 + 0 0
1 : 150 + 0
1 : 175 + + 0
1: 200 + + +
Phenol 1 : 90 + 0 0
1 : 100 + + +
0 = no growth, + = growth
The phenol – Coefficient of the disinfectant (X) would be
(A) 1.66
(B) 3.32
(C) 0.50
(D) 1.00
21. lactic acid bacteria ferment glucose to produce two moles of lactic acid. What is the net yield of ATP and NADH per mole of glucose?
(A) 2 ATP and 2 NADH
(B) 2 ATP and 0 NADH
(C) 4 ATP and 2 NADH
(D) 4 ATP and 0 NADH
Common Data Questions
Common Data for questions 22,23,24
Analysis of the electron transport system in a newly isolated aerobic. Gram – positive bacterium showed the existence of five electron transport molecules. Their redox potentials are as follows:
OXIDANT REDUCTANT
ELECTRON TRANSFERRED EO` (Volts)
P PH2 2 -0.13
NAD+ NADH 2 -0.32
R RH2 2 -0.02
Cytochrome c (+3) Cytochrome c (+2) 1 +o.22
S SH2 2 +0.63
Faraday Constant (F) = 23 kcal/ (volt.mole)
22. which of the following sequence of the electron transport carries would be involved in the transport of electrons for energy generations?
(A) P NAD+ R Cytochrome c S
(B) NAD+ P R Cytochrome c S
(C) NAD+ P Cytochrome c R S
(D) NAD+ Cytochrome c P R S
23. if the electrons are transferred from NADH to S, the difference in redox potential would be
24.
(A) +0.95 (B) +0.76 (C) – 0.95 (D) – 0.76
25. what would be the value of standard free energy change for the transfer of electorns form pH2 to S?
(A) – 17.5kcal/mol (B) – 35.0kcal/mol
(C)+17.5kcal/mol (D) +35.0kcal/mol
Common Data for questions 25,26:
E.coli can metabolize both glucose and lactose sugars as sole source of carbon and energy. While glucose catabolizing enzymes are constructive lactose catabolizing enzymes are induced in the presence of compounds such as lactose, IPTG, etc. Lactose catabolizing enzymes are also regulated by catabolite repression.
25. Assume that E.Coli has been grown in a nutrient medium containing lactose only. When the culture has
reached the logarithmic phase of growth, the cells are harvested and transferred to a medium glucose only. Would you expert the culture to
(A) Continue to grow in its logarithmic phase
(B) Exhibit a lag phase first and then grow again in its logarithmic phase
(C) Undergo lysis
(D) Stop growth
26. If the E.coli cells are gowth in a medium containing both glucose and lactose, what is likely to happen?
(A) Both the sugars would be utilized simultaneously
(B) The cultures will exhibit synchronous growth
(C) Lactose will be utilized first followed by glucose
(D) Glucose will be utilized first followed by lactose
Linked Answer Questions: Q27 a to Q28b carry two marks each
Statement for linked Answer Questions 27a & 27b: Consider a nutrient medium containing 2104 Cells. The culture is incubated at 25C under aerobic conditions for growing the cells. The generation time of the cells in 40minutes.
27a. If the culture is allowed to grow for 8 hours, how many generation would have taken place?
(A) 8 (B) 12 (C) 16 (D) 24
27b. What will be the cell population after 8 hours?
(A) 4.1105 (B) 8.2106 (C) 4.1107 (D) 8.2107
Statement for Linked Answer Questions 28a& 28/b: A mutant of E.coli was found which did not synthesize - galactosidase in the presence as well as in the absence of the inducer, IPTG. The investigation revealed that the structural genes of the lac operon were unaltered in the mutant, but one of the controlling genes (I of O) was mutated. The different allelic forms of the regulator gene and the operator gene are as follows:
I+ - Wild type regulator gene
Ic – Constitutive regulator
Is – Repressor form which is insensitive to inducer
O+ - Wild type operator gene
Oc – Constitutive operator
28a. which of the following mutation in the controlling genes was responsible for the above mentioned behaviour of the E.coli mutant?
(A) I+O+ (B) IcO+ (C) IsO+ (D) I+Oc
28b. On further mutation, the E.coli mutant synthesized - galactosidase in the presence of the inducer only. Which of the following mutant form would explain this observation?
(A) I+O+ (B) I+Oc (C) IsO+ (D) IsOc
Solutions
1. (B)
Discovered in 1970
2. (B)
3. (D)
The process is 2NO3- + 10e- + 12H+ N2 + 6H2O
4. (A)
5. (D)
Eubacteria have peptidoglycan cell wall containing muramic acid. Muramic acid is absent in Archea.
6. (C)
Anoxygenic photosynthesis bacteria e.g. Green sulphur purple sulphur
Oxygenic photosynthetic bacteria e.g. Cyanobacteria
7. (B)
Inorganic compounds are used as electron donors
8. (A)
9. (A)
It belongs to polyene class of antibiotics which have a large ring like structure, acts upon cells which have sterols in their cytoplasmic membranes.
10. (B)
(A) Hepatitis A – single stranded RNA
(B) Hepatitis B – DNA virus
(C) Hepatitis C – RNA virus
(D) Hepatitis E - virus; small circular RNA virus
11. (D)
Obligate aerobes and facultative anaerobes usually contain the enzymes S.O.D. and catalase to:
2O-2 +2H+ (SOD) O2 + H2O2
2H2)2 (Catalase) 2H2O + O2
Aerotolerant micro – organisms may lack catalase but all have S.O.D.
12. (C)
Penicillin inhibits transpeptidation, enzymes involved in the cross linking of the polysaccharide chains of the bacterial cell wall peptidoglycan. Activate cell wall lytic enzymes. Streptomycin binds with the 30s subunit of the bacterial ribosome to inhibit protein synthesis.
13. (A)
14. (C)
15. (D)
[TDTH] Delayed Type hypersensitivity T – Cells + Antigen presenting cells Proliferates and Release cytokines which attract lymphocytes, Macrophages, Basophiles to affected tissue.
16. (D)
Shift from slow aerobic to rapid anaerobic consumption of glucose was first noted by Pasteur.
17. (C)
The f factor is an episome and can integrate at several different locations by recombination.
18. (B)
Polio virus is a single stranded RNA virus.
19. (B)
20. (A)
Reciprocal of the appropriate=test dilution disinfectant(X) @10`
Reciprocal of the phenol dilution
= 15
9
=1.66
21. (B)
From Glucose 2pyruvate; 2NADH & 2ATP (Net gain)
Where during anaerobic homolactic fermentation 2NADH are utilized with 2ATP as Net gain.
22. (B)
23. (A)
E` = E` of electron acceptor – E` of electron donor
E = 0.63 – ( - 0.32 ) = 0.063+0.32 = +0.95
24. (B)
E` = E` of acceptor – E` of donour = 0.63 – ( - 0.13)
= 0.63+0.13 = 0.76
G = - nFE` = - 2(23kcal) 0.76
= -(2)(23)(0.76) = -34.96kcal/mol
25. (B)
The biphasic growth pattern or response is called DIAUXIC GROWTH. The cause of diauxic growth is not completely understood, but catabolite repression or the glucose effect plays a part. The enzymes for glucose catabolism is constitutive and unaffected by CAP activity.
26. (D)
Glucose CAMP deactivation of CAP inhibition oc lac operon
27a. (B)
Generation/Doubling time = 40 min
8 hrs = 8 60 in = 480 minutes
No of generations = 489/40 =12 generations/8 hrs
27b. (D)
n = log Nt - log No / log 2
n = log Nt – log No / 0.301
120.301 = log Nt – [log (2104)]
3.612 = log Nt – [log2+4 log 1] = log Nt- [0.301+4]
3.612 + 4.301 = log Nt
log Nt = 7.913
Nt = Antilog 0.913107 = 8185 107 8.2 107
28a. (C)
28b. (A)
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