GATE 2016 Question Paper with Answer Keys for Microbiology (XL-K)
XL-K: MICROBIOLOGY
Q. 1 – Q. 10 carry one mark each.
Q.1 Which one of the following is the most appropriate technique to determine the relatedness of two bacterial species?
(A) DNA hybridization
(B) Doubling time measurement
(C) Biochemical characterization
(D) Plasmid profiling
Ans: (A) DNA hybridization
Q.2 Which one of the following phages undergoes non-integrative lysogenic phase?
(A) λ
(B) P1
(C) T7
(D) M13
Ans: (B) P1
Q.3 Which one of the following is NOT a part of human microbiome?
(A) Propionibacterium acnes
(B) Lactobacillus casei
(C) Streptococcus suis
(D) Bacteroides fragilis
Ans: (C) Streptococcus suis
Q.4 Resident macrophages of _ are called Kupffer cells.
(A) brain
(B) liver
(C) lung
(D) kidney
Ans: (B) liver
Q.5 The enzyme responsible for generation of hypochlorous ions during phagocytosis is
(A) NADPH oxidase
(B) catalase
(C) myeloperoxidase
(D) superoxide dismutase
Ans: (C) myeloperoxidase
Q.6 Teichoic acid is composed of repetitive units of
(A) keto-deoxy octanoic acid
(B) glucose
(C) N-acetyl glucosamine
(D) glycerol
Ans: (D) glycerol
Q.7 Biofilm produced by bacteria is detected by
(A) Saffranin
(B) Malachite green
(C) Basic fuchsin
(D) Congo red
Ans: A ; D
Q.8 The precursor for the synthesis of aromatic amino acids is
(A) phosphoenolpyruvate
(B) pyruvate
(C) oxaloacetate
(D) α-ketoglutarate
Ans: (A) phosphoenolpyruvate
Q.9 The net yield of NADH in the Embden-Meyerhof pathway in E. coli is________.
Ans: 2.0 : 2.0
Q.10 E. coli ribonuclease contains 124 amino acids. The number of nucleotides present in the gene encoding the protein is ___.
Ans: 375 : 375
Q. 11 – Q. 20 carry two marks each.
Q.11 Which of the following infectious agents cross the blood-brain barrier?
(P) Streptococcus pneumoniae
(Q) Coxsackie virus
(R) Rotavirus
(S) Streptococcus pyogenes
(A) P & S
(B) R & S
(C) P & Q
(D) Q & R
Ans: (C) P & Q
Q.12 At OD540nm= 0.5, which one of the following bacterial mono-dispersed cell suspensions will have (i) maximum and (ii) minimum number of cells?
(P) Mycoplasma pneumoniae
(Q) Micrococcus luteus
(R) Bacillus subtilis
(S) Escherichia coli
(A) P & Q
(B) P & R
(C) Q & R
(D) R & S
Ans: (B) P & R
Q.13 Which one of the following enzyme combinations allows some bacteria to utilize acetate through glyoxylate pathway?
(P) Isocitrate lyase
(Q) Isocitrate dehydrogenase
(R) Succinyl CoA synthetase
(S) Malate synthase
(A) P & S
(B) P & R
(C) Q & S
(D) Q & R
Ans: (A) P & S
Q.14 The decimal reduction time (D121) for Clostridium botulinum spores is 0.2 min. The time required to reduce the spore count from 1012 to one spore at 121°C is_______ minutes.
Ans: 2.4 : 2.4
Q.15 E. coli requires three genes, galK (kinase), galT (transacetylase) and galE (epimerase) to utilize galactose. If there is a mutation in any one of these genes, the mutant cannot utilize galactose. Which one of the following combinations of merodiploids will support the growth of mutants on galactose?
(P) galK+galT+galE–/ galK–galT+galE–
(Q) galK–galT+galE–/ galK+galT–galE+
(R) galK+galT–galE–/ galK–galT–galE+
(S) galK+galT+galE–/ galK+galT–galE+
(A) P & Q
(B) P & R
(C) R & S
(D) Q & S
Ans: (D) Q & S
Q.16 Nitrogenase reduces N2 to NH3. Metal co-factors required for this activity are __.
(A) Fe & Cu
(B) Mo & Fe
(C) Mo & Mn
(D) Cu & Mn
Ans: (B) Mo & Fe
Q.17 If a bacterial cell contains 5,000 genes and if the average mutation frequency per gene is 2 ×10-4 per generation, the average number of new mutations per generation is _.
Ans: 1.0 : 1.0
Q.18 The growth profile of E. coli on glucose plus lactose is shown below. The specific growth rate of the second exponential phase is____h-1.
Ans: 0.10 : 0.11
Q.19 Match the cell structure components given in Group I with appropriate functions from Group II.
| Group I | Group II |
| (P) Cell membrane | (I) Nutrient transport |
| (Q) Purple membrane | (II) Photosynthesis |
| (R) Cisternae | (III) Active transport |
| (S) Outer membrane | (IV) Protein glycosylation |
| (V) Light-driven proton transport |
(A) P-I, Q-V, R-II, S-III
(B) P-I, Q-II, R-IV, S-III
(C) P-III, Q-II, R-V, S-I
(D) P-III, Q-V, R-IV, S-I
Ans: (D) P-III, Q-V, R-IV, S-I
Q.20 Match the antibiotics given in Group I with appropriate targets from Group II.
| Group I | Group II |
| (P) Nalidixic acid | (I) RNA polymerase |
| (Q) Tetracycline | (II) DNA gyrase |
| (R) Erythromycin | (III) DNA polymerase |
| (S) Rifampin | (IV) 50S ribosomal subunit |
| (V) Aminoacyl tRNA |
(A) P-III, Q-IV, R-V, S-I
(B) P-V, Q-I, R-IV, S-II
(C) P-II, Q-V, R-IV, S-I
(D) P-II, Q-V, R-I, S-IV
Ans: (C) P-II, Q-V, R-IV, S-I