Recent questions tagged microbiology

A bacterial strain is grown in nutrient medium at $37^{\circ}\text{C}$ under aerobic conditions. The medium is inoculated with $10^{2}$ cells from a seed culture. If the ...

Coronavirus genome consists ofdouble-stranded $\text{DNA}$double-stranded $\text{RNA}$negative-sense single-stranded $\text{RNA}$positive-sense single-stranded $\text{RNA...

$\text{CRISPR-Cas}$ system is associated withadaptive immunity in eukaryotesadaptive immunity in prokaryotesinnate immunity in eukaryotesinnate immunity in prokaryotes

Which one of the following is $\text{CORRECT}$ about microbial growth medium?Luria-Bertani broth is a synthetic mediumNutrient broth is a defined mediumSabouraud dextrose...

Decimal reduction time of a bacterial strain is $20 \textit{ min}$. Specific death rate constant in $\textit{min}^{-1}$ (rounded off to two decimal places) is ___________

Which of the following statement(s) is/are $\text{CORRECT}$ about $\textit{Agrobacterium tumefaciens}$?It contains tumor inducing plasmidIt causes crown gall disease in d...

Which of the following antimicrobial agent(s) is/are growth factor analog(s)?$5$-FluorouracilIsoniazidSulfanilamideTetracycline

A $0.1 \textit{ mL}$ aliquot of a bacteriophage stock having a concentration of $4 \times 10^9 \textit{ phages mL}^{-1}$ is added to $0.5 \textit{ mL}$ of $\textit{E. col...

A bacterium produces acetic acid from ethanol as per the following reaction $$2CH_3CH_2OH+2O_2 \rightarrow 2CH_3COOH+2H_2O$$ The thermodynamic maximum yield of acetic aci...

Which of the following factors can influence the lag phase of a microbial culture in a batch fermentor?Inoculum sizeInoculum ageMedium composition$P$ and $Q$ only$Q$ and ...

Phenolic wastewater discharged from an industry was treated with Pseudomonas $sp$. in an aerobic bioreactor. The influent and effluent concentrations of phenol were $10,0...

$W,X$ and $Y$ are the intermediates in a biochemical pathway as shown below:$$S \cdots \cdots \rightarrow W\rightarrow X\rightarrow Y\rightarrow Z$$Mutants auxotrophic fo...

Carl Woese used the gene sequence of which one of the following for phylogenetic taxonomy of prokaryotes?A ribosomal $RNA$ of large ribosomal subunitA ribosomal $RNA$ of...

A list of pathogens $(Group\; I)$ and a list of anti-microbial agents $(Group\; II)$ used to treat their infections are given below. Match the pathogens with the correspo...

Determine the correctness or otherwise of the following Assertion [$a$] and the Reason [$r$].Assertion [$a$]: Dam methylase protects $E$. coli $DNA$ from phage endonuclea...

A microorganism isolated from a salt-rich (salt concentration $\sim2$ $M$) lake was found to possess diglycerol tetraethers, with polyisoprenoid alcohol side chains, as t...

Tetracycline inhibits theinteraction between $tRNA$ and $mRNA$translocation of $mRNA$ through ribosomepeptidyl transferase activitybinding of amino-acyl $tRNA$ to ribosom...

Match the human diseases in $Group\; I$ with the causative agents in $Group\; II$.$$\begin{array}&&\textbf{Group I} & \textbf{Group II} \\ &\text{P. Amoebiasis} & \text{...

Which of the following processes can increase genetic diversity of bacteria in nature?ConjugationTransformationTransductionTransfection$P$ only$P$ and $Q$ only$P, Q$ and ...

Which one of the following can NOT be a limiting substrate if Monod's growth kinetics is applicable?Extracellular carbon sourceExtracellular nitrogen sourceDissolved oxyg...

Bacteria with two or more flagella at one or both ends are calledamphitrichousperitrichouslophotrichousatrichous

Which family of viruses has single stranded DNA?HerpesviridaePoxviridaeRetroviridaeParvoviridae

Which of the following are TRUE for Treponema pallidum?It is the causative agent of syphilisIt is a spirocheteIt is a non-motile bacteriumIt is generally susceptible to p...

A biological process is involved in the __________ treatment of industrial effluent.primarysecondarytertiaryquaternary

Which combination of the following statements is CORRECT for cyanobacteria?They can perform oxygenic photosynthesisUsually filamentous forms are involved in nitrogen fixa...

Which of the following events occur during the stationary phase of bacterial growth?Rise in cell number stopsSpore formation in some Gram-positive bacteria such as Bacill...

Select the CORRECT combination of genetic components that are essential for the transfer of T-DNA segment from Agrobacterium tumefaciens to plant cells.Border repeat sequ...

$\textit{Saccharomyces cerevisiae}$ is cultured in a chemostat (continuous fermentation) at a dilution rate of $0.5 \: h^{-1}$. The feed substrate concentration is $10 \:...

Decimal reduction time of bacterial spores is $23$ min at $121 ^\circ C$ and the death kinetics follow first order. One liter medium containing $10^5$ spores per $mL$ was...

Which one of the following organisms is an indicator of fecal contamination?$\textit{Escherichia coli}$$\textit{Streptococcus lactis}$$\textit{Bacillus subtilis}$$\textit...

Which one of the following mechanisms is used by human pathogens to evade host immune responses?Somatic hypermutationAntibody productionAntigenic variationComplement acti...

Assertion [a]: Gram negative bacteria show staining with saffranin.Reason [r]: Gram negative bacteria have an outer membrane with lipopolysaccharides.Both [a] and [r] are...

Macrophages eliminate pathogenic bacteria upon activation byNK cellsbasophilsCD$4+$ T cellsplasma cells

Match the organisms in $\text{Column I}$ with the characteristics in $\text{Column II}$:$\begin{array}{|l|l|l|l|} \hline & \textbf{Column I} && \textbf{Column II} \\ \hli...

Which one of the following organisms is responsible for crown gall disease in plants?$\textit{Xanthomonas campestris}$$\textit{Rhizobium etli}$$\textit{Agrobacterium tume...

For an $\textit{E.coli}$ culture in the exponential phase of growth, optical density (OD) at $540$ nm is $0.3$ at $2$ hours and $0.6$ at $4$ hours. Assuming that the meas...

An immunocompetent person becomes infected with a pathogenic strain of bacteria. Which one of the following graphs correctly depicts bacterial load in this person over ti...

Growth of a microbe in a test tube is modeled as $\dfrac{dX}{dt} = rX \bigg (1 – \dfrac{X}{K}\bigg )$, where, $X$ is the biomass, $r$ is the growth rate, and $K$ is the c...