GATE Overflow for GATE ESE - Recent questions in Growth and Control of Microorganisms

GATE ES 2026 | Question: 44

Mon, 23 Feb 2026 13:14:31 +0000

A thermal process, at a specific temperature, results in $2-\log _{10}$ 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).

GATE ES 2026 | Question: 43

Mon, 23 Feb 2026 13:14:31 +0000

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).

GATE ES 2024 | Question: 34

Mon, 19 Feb 2024 10:24:08 +0000

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

Ethanol damages lipid structures in the bacterial cell membrane
Mercuric chloride inactivates cellular enzymes containing sulfhydryl groups
Glutaraldehyde inactivates protein
Isopropyl alcohol cannot be used as a disinfectant.

GATE ES 2021 | Question: 24

Tue, 14 Mar 2023 03:44:26 +0000

In a sample, the growth of microbial cells started with an initial concentration of $5 \times 10^4$ cells per millilitre $(\mathrm{mL})$ of the sample. After a certain time period, the cell concentration was found to be $1280 \times 10^4$ cells per $\mathrm{mL}$ of the sample. Assuming binary fission of cells and no cell death, the number of generations of cell growth occurred in this time period is $\text{(answer in integer)}$.