Microbial Metabolism - Environmental Microbiology - Environmental Science & Engineering Previous Year Questions

1

2025 · Environmental Science & Engineering · Environmental Microbiology · Microbial Metabolism

Environmental Science & Engineering (ES) 2025

Consider the following statements related to nitrification process:
(i) Electron acceptor type vary depending on whether nitrosomonas or nitrobacter is involved.
(ii) Predominant carbon source is organic matter.
(iii) Predominant carbon source is inorganic carbon.
(iv) Electron donor during conversion of ammonium ions to nitrite ions is ammonium ions.
Choose the correct option(s) from the following

A

(iii) and (iv) are correct

B

(i) and (ii) are correct

C

(i) is incorrect and (iii) is correct

D

(ii) is correct and (iii) is incorrect

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2

2025 · Environmental Science & Engineering · Environmental Microbiology · Microbial Metabolism

Environmental Science & Engineering (ES) 2025

Consider the following statements on microbial metabolism
(i) Utilization of carbon for cell synthesis is termed as anabolism.
(ii) During catabolism, adenosine triphosphate (ATP) is converted into adenosine diphosphate (ADP).
Choose the correct option from the following

A

(i) and (ii) are correct

B

(i) and (ii) are incorrect

C

(i) is correct and (ii) is incorrect

D

(i) is incorrect and (ii) is correct

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3

2025 · Environmental Science & Engineering · Environmental Microbiology · Microbial Metabolism

Environmental Science & Engineering (ES) 2025

Aerobic biomass has yield coefficient value of 0.4 for glucose (molecular weight = 180 g/mole) substrate. Bacteria is represented as C₅H₇O₂N (molecular weight = 113 g/mole). Assume that no endogenous metabolism occurs. The percentage of carbon going into CO₂ from 1 mole/L glucose is _________. (rounded off to two decimal places)

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4

2021 · Environmental Science & Engineering · Environmental Microbiology · Microbial Metabolism

Environmental Science & Engineering (ES) 2021

Which of the following is the terminal electron acceptor in the electron transport chain of aerobic respiration?

A

Water

B

NADH

C

\(O_2\)

D

Cytochrome-c

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5

2021 · Environmental Science & Engineering · Environmental Microbiology · Microbial Metabolism

Environmental Science & Engineering (ES) 2021

Which of the following is/are correct for the process of glycolysis?

A

There is net decrease in standard Gibbs free energy.

B

The end product is glyceraldehyde 3-phosphate.

C

First phase includes the phosphorylation of the glucose molecule.

D

It results in the net gain of NADH.

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6

2023 · Environmental Science & Engineering · Environmental Microbiology · Microbial Metabolism

Environmental Science & Engineering (ES) 2023

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

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7

2023 · Environmental Science & Engineering · Environmental Microbiology · Microbial Metabolism

Environmental Science & Engineering (ES) 2023

The ratio of the moles of CO₂ evolved to the moles of O₂ consumed in respiration also called the respiratory quotient, is calculated for a carbohydrate (C₆H₁₂O₆) as substrate and found to be 1. Under similar conditions, for a fatty acid (C₅₁H₉₈O₆) as substrate, the respiratory quotient is __________ (rounded off to two decimal place).

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8

2023 · Environmental Science & Engineering · Environmental Microbiology · Microbial Metabolism

Environmental Science & Engineering (ES) 2023

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

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9

2026 · Environmental Science & Engineering · Environmental Microbiology · Microbial Metabolism

Environmental Science & Engineering (ES) 2026

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

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10

2026 · Environmental Science & Engineering · Environmental Microbiology · Microbial Metabolism

Environmental Science & Engineering (ES) 2026

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.

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