List of top Environmental Microbiology Questions asked in GATE ES

A common effluent treatment plant with a capacity of 2 million litres per day (MLD) employs reverse osmosis (RO) for water reuse. The RO unit removes 95% of the total dissolved solids (TDS) and the water recovery rate is 70%. If the TDS concentration in the RO feed is 8000 parts per million (ppm), the TDS in the RO reject is ________ g/L. (rounded off to one decimal place)

Choose the correct option(s) for removing solids from water.

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

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:

Choose the correct statement(s) from the following regarding the structure/reproduction of microorganisms:

Which one of the following is performed by autotrophic bacteria?

Rod shaped bacterial cells are called _______.

Tuberculosis is predominantly caused by ________.

Enzymes with the class of enzymes are listed in the table. Enzyme Class of Enzyme

Enzymes	class of enzymes
(a) Lactate dehydrogenase	(i) Isomerases
(b) Alanine racemase	(ii) Transferases
(c) Lipase	(iii) Oxidoreductases
(d) Hexokinase	(iv) Hydrolases

Select the correct match(es)

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

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

Kit Performance in an Outbreak
A researcher compiled the following information about the performance of a kit in an outbreak:

Infection State	Kit Response
Disease (probability = 0.002)	Positive response (probability = 0.98)
No Disease	Positive response (probability = 0.03)

The probability of detecting an infection for a positive result through the kit would be ______________________ (rounded off to three decimal places).

The kinematic viscosity of glycerin and kerosene are 1.2 times and 0.95 times of that of water, respectively. Glycerin and kerosene flow through two identical porous media having same hydraulic gradient. Assuming Darcy’s law is valid for the porous media, the ratio of flow rate of kerosene to that of glycerin is:

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:

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

A typical plasmid-free bacterial cell having a single chromosome consists of $\sim 55%$ protein, $\sim 3%$ DNA and $\sim 21%$ RNA (percent of dry weight). Assuming there are 2500 different types of protein molecules (with at least one copy number) being expressed in a bacterial cell at any given time, which of the following statements is/are NOT correct with respect to the number of intracellular DNA, RNA and protein molecules?

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. The reactor is subjected to a perturbation by reducing the HRT to 12 hours. The reactor recovers and comes to a new steady state with a specific growth rate of $\mu_2$. Which one of the following statements is correct?

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?

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?

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°C for 48 hours, the agar plates showed an average of 64 colonies per plate. What was the average concentration of coliform organisms (in CFU/ml) in the original water sample?