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Prokaryotic and Eukaryotic Microorganisms(6)Cell Chemistry and Cell Biology(3)Microbial Metabolism(8)Growth and Control of Microorganisms(6)Microbiology and Health(2)

Prokaryotic and Eukaryotic Microorganisms

6 Questions

GATE→2024→Environmental Microbiology→Prokaryotic and Eukaryotic Microorganisms

Q1

MCQ[1 Mark]

Rod shaped bacterial cells are called

(A)

Bacilli

(B)

Cocci

(C)

Spirilla

(D)

Diplococci

Explanation

GATE→2024→Environmental Microbiology→Prokaryotic and Eukaryotic Microorganisms

Q2

MCQ[1 Mark]

Which one of the following is associated with biological nitrogen fixation?

(A)

Atmospheric nitrogen to ammonia by Rhizobium bacteria in nodules attached to roots of legumes under aerobic conditions

(B)

Atmospheric nitrogen to ammonia by Rhizobium bacteria in nodules attached to roots of legumes under anaerobic conditions

(C)

Azotobacter species under aerobic conditions

(D)

Azotobacter species under anaerobic conditions

Explanation

GATE→2023→Environmental Microbiology→Prokaryotic and Eukaryotic Microorganisms

Q3

MCQ[1 Mark]

Read the following statements: I. Photosynthesis takes place within the chloroplasts of the eukaryotes, whereas the breakdown of complex molecules to yield energy takes place in the cytoplasm and in the mitochondria. II. Photosynthesis takes place within the chloroplasts of the prokaryotes, whereas the breakdown of complex molecules to yield energy takes place in the cytoplasm and in the mitochondria. III. All living organisms retain the enzymatic machinery to partially oxidise glucose without the help of oxygen. This breakdown of glucose to pyruvic acid is called glycolysis. IV. ... The correct choice is

(A)

I and III are correct

(B)

II and IV are correct

(C)

I is correct whereas III is incorrect

(D)

II is correct whereas IV is incorrect

Explanation

GATE→2023→Environmental Microbiology→Prokaryotic and Eukaryotic Microorganisms

Q4

MCQ[2 Marks]

Which one of the following statements is NOT correct?

(A)

Photophosphorylation is the synthesis of ATP from ADP and inorganic phosphate in the presence of light.

(B)

The process through which ATP is synthesised by cells (in mitochondria and chloroplasts) is called phosphorylation.

(C)

The Calvin cycle (carboxylation, reduction, and regeneration) occurs in all photosynthetic plants (C3, C4 or any other).

(D)

C3 plants have a special type of leaf anatomy, they tolerate higher temperatures, they show a response to high light intensities, have high rate of photosynthesis and reduced rate of photorespiration as compared to C4 plants.

Explanation

GATE→2023→Environmental Microbiology→Prokaryotic and Eukaryotic Microorganisms

Q5

MCQ[2 Marks]

Read the following statements: I. Bacteriophage is an anaerobic bacterium. II. Male-specific bacteriophage infect via the pili of other microorganisms including viruses. III. Bacteriophage is found in human as well as in animal excreta. IV. Bacteriophage can not indicate the presence of bacteria. The correct choice is

(A)

(I), (III) and (IV) are correct

(B)

(IV) is correct; (III) is incorrect

(C)

Both (III) and (IV) are incorrect

(D)

Both (III) and (IV) are correct

Explanation

GATE→2022→Environmental Microbiology→Prokaryotic and Eukaryotic Microorganisms

Q6

MCQ[1 Mark]

Reverse Transcriptase Polymerase Chain Reaction is an analytical procedure used in detection of pathogenic microorganisms. Which one of the following statements is NOT correct in this context?

(A)

It is used for identifying presence or absence of specific RNA in samples.

(B)

It is used only for identifying Corona Viruses, including SARS CoV2 in samples.

(C)

It cannot differentiate between viable and inactivated viruses.

(D)

It is based on conversion of RNA to DNA followed by DNA amplification.

Explanation

Cell Chemistry and Cell Biology

3 Questions

GATE→2026→Environmental Microbiology→Cell Chemistry and Cell Biology

Q7

MCQ[2 Marks]

Which ONE of the following options is CORRECT with respect to sequential breakdown of deoxyribonucleic acid (DNA) into lower-molecular weight compounds?

(A)

Deoxyribonucleic acid $\rightarrow$ 2-deoxyribose $\rightarrow$ Nucleosides $\rightarrow$ Nucleotides

(B)

Deoxyribonucleic acid $\rightarrow$ 2-deoxyribose $\rightarrow$ Nucleotides $\rightarrow$ Nucleosides

(C)

Deoxyribonucleic acid $\rightarrow$ Nucleotides $\rightarrow$ Nucleosides $\rightarrow$ 2-deoxyribose

(D)

Deoxyribonucleic acid $\rightarrow$ Nucleosides $\rightarrow$ Nucleotides $\rightarrow$ 2-deoxyribose

Explanation

GATE→2024→Environmental Microbiology→Cell Chemistry and Cell Biology

Q8

MSQ[2 Marks]

Which of the following statement(s) is/are CORRECT?

(A)

DNA is composed of nucleotides.

(B)

Five types of nitrogenous bases occur in DNA.

(C)

Each phosphate is attached to two deoxyribose units in a single strand of DNA.

(D)

The ratio of adenine to guanine is always 1:1 in a double stranded DNA.

Explanation

GATE→2022→Environmental Microbiology→Cell Chemistry and Cell Biology

Q9

MSQ[2 Marks]

A typical plasmid-free bacterial cell having a single chromosome consists of ~55% protein, ~3% DNA and ~21% RNA... Which of the following statement(s) is/are NOT correct with respect to the number of intracellular DNA, RNA and protein molecules?

(A)

$DNA = RNA = Protein \ge 2500$

(B)

$DNA = RNA = 1; Protein \ge 2500$

(C)

$DNA = 1; RNA = Protein \ge 2500$

(D)

$DNA = 1; RNA > Protein \ge 2500$

Explanation

Microbial Metabolism

8 Questions

GATE→2026→Environmental Microbiology→Microbial Metabolism

Q10

MCQ[1 Mark]

The major class of enzymes catalyzing the cleavage of C-C, C-O, C-N, or other bonds by elimination, leaving double bonds or rings, or addition of groups to double bonds in any biochemical reactions is

(A)

lyases

(B)

transferases

(C)

oxidoreductases

(D)

hydrolases

Explanation

GATE→2026→Environmental Microbiology→Microbial Metabolism

Q11

MSQ[2 Marks]

Which of the following statements is/are CORRECT based on the electron donor (ED) and electron acceptor (EA) used in various bacterial mediated reactions in wastewater treatment?

(A)

In anaerobic heterotrophic acid fermentation, organic compounds are used as both ED and EA.

(B)

In anaerobic heterotrophic methanogenesis, volatile fatty acids and CO2 are used as ED and EA, respectively.

(C)

In denitrification process by denitrifiers, organic compounds and CO2 are used as ED and EA, respectively.

(D)

In aerobic autotrophic iron oxidation, Fe(II) and O2 are used as ED and EA, respectively.

Explanation

GATE→2024→Environmental Microbiology→Microbial Metabolism

Q12

MSQ[2 Marks]

Enzymes with the class of enzymes are listed in the table. - (a) Lactate dehydrogenase - (b) Alanine racemase - (c) Lipase - (d) Hexokinase Classes: (i) Isomerases, (ii) Transferases, (iii) Oxidoreductases, (iv) Hydrolases Select the correct match(es)

(A)

(a) - (iii); (b) - (i)

(B)

(c) - (iv); (d) - (ii)

(C)

(a) - (ii); (b) - (iv)

(D)

(c) - (iii); (d) - (i)

Explanation

GATE→2023→Environmental Microbiology→Microbial Metabolism

Q13

MCQ[1 Mark]

Read the following statements: i. Aerobic heterotrophic bacteria uses organic matter for carbon source and energy source. ii. Aerobic heterotrophic bacteria uses carbon dioxide for carbon source and energy source. in. Aerobic autotrophic bacteria uses carbon dioxide for carbon source and reduced substances for energy source. iv. Aerobic autotrophic bacteria uses organic matter for getting energy. The correct choice is

(A)

(i) is correct; (iii) is correct

(B)

(iv) is correct; (i) is incorrect

(C)

(i) is correct; (iv) is correct

(D)

(ii) is correct; (iv) is incorrect

Explanation

GATE→2023→Environmental Microbiology→Microbial Metabolism

Q14

MCQ[1 Mark]

A student wants to decide electron acceptor for aerobic, facultative and anaerobic bacteria. In this context, read the following statements: i. Dissolved Oxygen (DO) can act as electron acceptor for aerobic bacteria. ii. Nitrite can act as electron acceptor for aerobic bacteria. iii. Dissolved Oxygen (DO) can act as electron acceptor for anaerobic bacteria. iv. Nitrite can act as electron acceptor for facultative bacteria. The correct choice is

(A)

(i) is correct; (iv) is correct

(B)

(ii) is correct; (iii) is incorrect

(C)

(ii) is correct; (iii) is correct

(D)

(i) is correct; (ii) is correct

Explanation

GATE→2023→Environmental Microbiology→Microbial Metabolism

Q15

NAT[1 Mark]

The ratio of the moles of $CO_2$ evolved to the moles of $O_2$ consumed in respiration also called the respiratory quotient, is calculated for a carbohydrate ($C_6H_{12}O_6$) as substrate and found to be 1. Under similar conditions, for a fatty acid ($C_{51}H_{98}O_6$) as substrate, the respiratory quotient is _____ (rounded off to two decimal place).

Explanation

GATE→2023→Environmental Microbiology→Microbial Metabolism

Q16

MCQ[2 Marks]

Read the following statements: i. In endogenous metabolism by aerobic bacteria, electron acceptor is present inside the cells. ii. In endogenous metabolism by aerobic bacteria, electron acceptor is dissolved oxygen. iii. The endogenous metabolism is linked to fermentative metabolism. iv. In exogenous metabolism by aerobic bacteria, enzyme mediated electron transfer happens within the cells. The correct choice is

(A)

(i) is correct; (iii) is correct

(B)

(ii) is correct; (iii) is incorrect

(C)

(iii) is incorrect; (iv) is incorrect

(D)

(iii) is correct; (iv) is correct

Explanation

GATE→2023→Environmental Microbiology→Microbial Metabolism

Q17

NAT[2 Marks]

A biological reactor is getting wastewater containing $1\text{ mole/L}$ acetate ions as carbon source. The following reaction takes place in the bio-reactor: $0.125 CH_3COO^- + 0.0295 NH_4^+ + 0.103 O_2 \rightarrow 0.0295 C_5H_7O_2N + 0.0955 H_2O + 0.095 HCO_3^- + 0.007 CO_2$ Given that $1\text{ g}$ acetate exerts $1.07\text{ g COD}$; $1\text{ mole}$ bacteria $= 113\text{ g VSS}$; $1\text{ mole}$ acetate ion $= 59\text{ g}$. Value of observed yield is _____ (in $\text{g VSS/g COD}$, rounded off to two decimal places).

Explanation

Growth and Control of Microorganisms

6 Questions

GATE→2026→Environmental Microbiology→Growth and Control of Microorganisms

Q18

NAT[2 Marks]

In a batch culture experiment, 2 cells of a microorganism were added to a growth medium. During the experiment, a lag phase of 1 hour was first experienced by the added cells, in which no cell multiplication occurred. Afterwards, cells started multiplying exponentially with a doubling time of 1 hour. After total 8 hours of experiment, the number of cells present in the growth medium was _____ (answer in integer).

Explanation

GATE→2026→Environmental Microbiology→Growth and Control of Microorganisms

Q19

NAT[2 Marks]

A thermal process, at a specific temperature, results in 2-log10 removal of non-thermotolerant pathogenic microorganisms from a water sample in 20 min. The time needed to achieve 99.999% removal of these microorganisms under similar condition is _____ min (answer in integer).

Explanation

GATE→2024→Environmental Microbiology→Growth and Control of Microorganisms

Q20

MSQ[2 Marks]

With reference to disinfection, which of the following statement(s) is/are CORRECT?

(A)

Ethanol damages lipid structures in the bacterial cell membrane.

(B)

Mercuric chloride inactivates cellular enzymes containing sulfhydryl groups.

(C)

Glutaraldehyde inactivates protein.

(D)

Isopropyl alcohol cannot be used as a disinfectant.

Explanation

GATE→2022→Environmental Microbiology→Growth and Control of Microorganisms

Q21

MCQ[1 Mark]

Ten litres of the sample was filtered through a membrane filter and the filter was transferred to solid agar media which supports growth of coliform organisms. After incubation at $37^\circ\text{C}$ for 48 hours, the agar plates showed an average of 64 colonies per plate. What was the average concentration of coliform organisms (in Colony Forming Units per unit volume) in the original water sample?

(A)

$64\text{ CFU/ml}$

(B)

$640\text{ CFU/ml}$

(C)

$6.4 \times 10^{-3}\text{ CFU/ml}$

(D)

$64 \times 10^{-3}\text{ CFU/ml}$

Explanation

GATE→2022→Environmental Microbiology→Growth and Control of Microorganisms

Q22

MCQ[2 Marks]

For an exponentially growing microbial culture, the specific growth rate ($\mu$) is related to its doubling time ($t_d$) by which one of the following relations?

(A)

$t_d = \mu$

(B)

$t_d = \mu^2$

(C)

$t_d = \frac{1}{\mu} \ln 2$

(D)

$t_d = \frac{1}{2} \ln \mu$

Explanation

GATE→2022→Environmental Microbiology→Growth and Control of Microorganisms

Q23

MCQ[2 Marks]

A microbial culture, with a specific growth rate of $\mu_1$ (per hour), is being grown in a continuous reactor at steady state with hydraulic retention time (HRT) of 24 hours. This reactor is subjected to a perturbation by reducing the HRT to 12 hours. The reactor recovers from the perturbation and comes to a new steady state with a new specific growth rate of $\mu_2$ (per hour). Which one of the following statements is correct?

(A)

$\mu_1 = \mu_2$

(B)

$\mu_1 = 0.5 \mu_2$

(C)

$\mu_2 = 0.5 \mu_1$

(D)

$\mu_2 = e^{0.5} \mu_1$

Explanation

Microbiology and Health

2 Questions

GATE→2026→Environmental Microbiology→Microbiology and Health

Q24

MCQ[1 Mark]

Malaria is caused by pathogenic

(A)

bacteria

(B)

fungi

(C)

protozoa

(D)

viruses

Explanation

GATE→2024→Environmental Microbiology→Microbiology and Health

Q25

MCQ[1 Mark]

Tuberculosis is predominantly caused by

(A)

Entamoeba histolytica

(B)

Salmonella typhi

(C)

Mycobacterium bovis

(D)

Bacillus cereus

Explanation