GATE Overflow for GATE ESE - Recent questions in Microbial Metabolism

GATE ES 2026 | Question: 33

Mon, 23 Feb 2026 13:14:45 +0000

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

In anaerobic heterotrophic acid fermentation, organic compounds are used as both $\text{ED}$ and $\text{EA}$.
In anaerobic heterotrophic methanogenesis, volatile fatty acids and $\mathrm{CO}_{2}$ are used as $\text{ED}$ and $\text{EA}$, respectively.
In denitrification process by denitrifiers, organic compounds and $\mathrm{CO}_{2}$ are used as $\text{ED}$ and $\text{EA}$, respectively.
In aerobic autotrophic iron oxidation, $\text{Fe} \text{(II)}$ and $\mathrm{O}_{2}$ are used as $\text{ED}$ and $\text{EA}$, respectively.

GATE ES 2025 | Question: 5

Thu, 06 Mar 2025 16:22:47 +0000

Which one of the following is performed by autotrophic bacteria?

Aerobic biodegradation of organic matter
Anaerobic biodegradation of organic matter
Aerobic nitrification
Anaerobic de-nitrification

GATE ES 2025 | Question: 28

Thu, 06 Mar 2025 16:21:43 +0000

Consider the following statements on microbial metabolism

Utilization of carbon for cell synthesis is termed as anabolism.
During catabolism, adenosine triphosphate (ATP) is converted into adenosine diphosphate (ADP).

Choose the correct option from the following

(i) and (ii) are correct
(i) and (ii) are incorrect
(i) is correct and (ii) is incorrect
(i) is incorrect and (ii) is correct

GATE ES 2025 | Question: 34

Thu, 06 Mar 2025 16:21:24 +0000

If microbial growth occurs under substrate unlimited conditions, according to Monod's kinetics, choose the correct option(s) from the following

Microbial growth follows zero order with respect to substrate concentration.
Microbial growth follows first order with respect to substrate concentration.
Specific growth rate is half of maximum specific growth rate.
Specific growth rate is almost equal to maximum specific growth rate.

GATE ES 2023 | Question: 29

Tue, 23 May 2023 03:12:14 +0000

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

$\text{(i)}$ is correct; $\text{(iii)}$ is correct
$\text{(ii)}$ is correct; $\text{(iii )}$ is incorrect
$\text{(iii)}$ is incorrect; $\text{(iv)}$ is incorrect
$\text{(iii)}$ is correct; $\text{(iv)}$ is correct

GATE ES 2022 | Question: 28

Fri, 17 Feb 2023 07:05:51 +0000

For an exponentially growing microbial culture, the specific growth rate $(\mu)$ is related to its doubling time $\left(\mathrm{t}_{\mathrm{d}}\right)$ by which one of the following relations?

$\quad t_{d}=\mu$
$\mathrm{t}_{\mathrm{d}}=\mu^{2}$
$\mathrm{t}_{\mathrm{d}}=\frac{1}{\mu} \ln 2$
$\quad t_{d}=\frac{1}{2} \ln \mu$

GATE ES 2022 | Question: 29

Fri, 17 Feb 2023 07:05:50 +0000

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?

$\quad \mu_{1}=\mu_{2}$
$\quad \mu_{1}=0.5 \mu_{2}$
$\mu_{2}=0.5 \mu_{1}$
$\quad \mu_{2}=e^{0.5} \mu_{1}$