LinkedIn Insight GATE 2015 Question Paper with Answer Keys for Microbiology (XL-K) - Grad Plus

GATE 2015 Question Paper with Answer Keys for Microbiology (XL-K)


Q. 1 – Q. 10 carry one mark each.

Q.1 Lophotrichous bacteria have

(A) one flagellum

(B) a cluster of flagella at one or both ends

(C) flagella that are spread evenly over the whole surface

(D) a single flagellum at each pole

Ans: (B) a cluster of flagella at one or both ends

Q.2 In aerobic respiration, the final electron acceptor is

(A) hydrogen

(B) nitrogen

(C) sulfur

(D) oxygen

Ans: (D) oxygen

Q.3 A process in which fatty acids are shortened by two carbons at a time resulting in release of acetyl-CoA is known as

(A) photophosphorylation

(B) carboxylation

(C) β-oxidation

(D) oxidative phosphorylation

Ans: (C) β-oxidation

Q.4 Limulus Amoebocyte Lysate (LAL) assay is used to identify the presence of

(A) endotoxin

(B) exotoxin

(C) anthrax toxin

(D) tetanus toxin

Ans: (A) endotoxin

Q.5 Match scientists in Group I with terms related to their major scientific contributions in Group II

Group IGroup II
(P)Sanger(i) DNA double helix structure
(Q) Watson and Crick(ii) DNA sequencing
(R) Waksman(iii)Complement
(S) Bordet(iv) Streptomycin
(v)Immune tolerance

(A) P-iii, Q-iv, R-ii, S-i

(B) P-ii, Q-iii, R-iv, S-v

(C) P-iv, Q-i, R-ii, S-v

(D) P-ii, Q-i, R-iv, S-iii

Ans: (D) P-ii, Q-i, R-iv, S-iii

Q.6 Base-pair substitutions caused by the chemical mutagen ethyl methane sulfonate are a result of

(A) hydroxylation

(B) alkylation

(C) deamination

(D) intercalation

Ans: (B) alkylation

Q.7 The classical way of representing taxonomic hierarchy of living organisms in ASCENDING ORDER is

(A) genus, species, class, order, family

(B) species, genus, order, family, class

(C) species, genus, family, order, class

(D) genus, species, order, class, family

Ans: (C) species, genus, family, order, class

Q.8 Of the following, the most effective method to kill bacterial endospores is

(A) moist heat sterilization

(B) UV irradiation

(C) filtration

(D) pasteurization

Ans: (A) moist heat sterilization

Q.9 The class of enzymes, which catalyze addition of groups to double bonds and non-hydrolytic removal of chemical groups, is

(A) oxidoreductase

(B) transferase

(C) hydrolase

(D) lyase

Ans: (D) lyase

Q.10 Anammox organisms carry out

(A) anaerobic reduction of $latex NO_3^-$

(B) anaerobic oxidation of $latex NH_4^+$

(C) aerobic oxidation of $latex NH_4^+$

(D) aerobic oxidation of $latex NO_2^-$

Ans: (B) anaerobic oxidation of $latex NH_4^+$

Q. 11 – Q. 20 carry two marks each.

Q.11 Which combination of the following statements about specialized transduction is TRUE?

(P) Specialized transducing phages can transport only certain genes between bacteria
(Q) Specialized transducing phages can transport any gene between bacteria
(R) Phage P22 is a specialized transducing phage
(S) Phage lambda (λ) is a specialized transducing phage

(A) P and S only

(B) Q and R only

(C) P and R only

(D) Q and S only

Ans: (A) P and S only

Q.12 Which combination of profiles in the following figure accurately represents the transport rate of glycerol and oxygen into E. coli cells as a function of their extracellular concentration?

XL Gate

(A) glycerol-(ii) and oxygen-(iii)

(B) glycerol-(ii) and oxygen-(i)

(C) glycerol-(iii) and oxygen-(i)

(D) glycerol-(i) and oxygen-(ii)

Ans: (D) glycerol-(i) and oxygen-(ii)

Q.13 Which one of the following about the standard free energy change (ΔGo′) and the equilibrium constant (Keq) of an exergonic reaction, at pH 7.0, is TRUE?

(A) ΔGo′ is positive and Keq is less than one

(B) ΔGo′ is negative and Keq is less than one

(C) ΔGo′ is negative and Keq is greater than one

(D) ΔGo′ is positive and Keq is greater than one

Ans: (C) ΔGo′ is negative and Keq is greater than one

Q.14 An oil immersion objective of a light microscope has a numerical aperture of 1.25. Using the Abbé equation, the maximum theoretical resolving power (in nm) of the microscope with this objective and blue light (wavelength = 450 nm) is __

Ans: 180

Q.15 The working volume (in liter) of a chemostat with 0.1 h-1 dilution rate and 100 ml/h feed flow rate is______

Ans: 1

Q.16 If the decimal reduction time for spores of a certain bacterium at 121oC is 12 seconds, the time required (in minutes) to reduce 1010 spores to one spore by heating at 121oC is _

Ans: 2

Q.17 The doubling time (in minutes) of a bacterium with a specific growth rate of 2.3 h-1 in 500 ml of growth medium is __

Ans: 17.9 to 18.3

Q.18 A bacterial culture is grown using 2.0 mg/ml fructose as the sole source of carbon and energy. The bacterial biomass concentrations immediately after inoculation and at the end of the growth phase are 0.1 mg/ml and 0.9 mg/ml, respectively. Assuming complete utilization of the substrate, the bacterial growth yield (Y) on fructose is __

Ans: 0.4

Q.19 The volume (in ml) of a 1.0 mg/ml stock solution of ampicillin to be added to 0.1 liter of growth medium for achieving a final ampicillin concentration of 50 μg/ml is __

Ans: 5

Q.20 An E. coli strain is grown initially on glucose as the sole carbon source. Upon complete consumption of glucose following 12 h of growth, lactose is added as the sole carbon source and
the strain is further grown for 12 h. Assuming that the E. coli strain has a functional wild type lac operon, which one of the following profiles is the most ACCURATE representation of β-
galactosidase (β-gal) expression (in arbitrary units)?


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XL gate


xl gate


xl gate

Ans: (D)

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