Microbiology MCQ 1 - Biotechnology Engineering (BT) MCQ

Cryptic growth means hidden growth of some of individual cells in a starving bacteria in death phase. The majority of cells do not grow at all in death phase but a few cells are able to multiply because these cells use product of lysis of dying cells.

Among given options, S. aureus is non motile and hence does not have flagella, E.coli and S. typhi both have peritrichous arrangement of flagella. Only V. cholera has monotrichous arrangement of flagella.

Bacterial endospores are stained using schaeffer-fulton procedure with malachite green.

The capsomer is a subunit of the capsid , an outer covering of protein that protects the genetic material of a virus. Capsomers self assemble to form the capsid.

The core of the endospore plays an important role in resistance from various unfavorable conditions. Dipicolinic acid combined with calcium ions is present in the core & plays a part in resistance.

As specific growth is equal to ln 2/ Doubling time
Specific growth (µ) = 0.693/50
= 0.0138min^–1

Dividing time is 45 minutes. Total time is 180 minutes
Number of generations after 180 minutes = 180 45 = 4
Now applying the formula
N = N₀ x 2ⁿ where N = Final number of cells., N₀ = Initial number of cells
N = number of generations

Facultative anaerobes are those that does not require  O₂ for their growth but grows better in the presence of  O₂.

Helicobacter pylori causes the peptic ulcer
Haemophilus aegyptius causes eye infection
Campylobacter jejuni causes diarrahea
Bordetella pertusis causes whopping cough

Culture media is always autoclaved before using. Serum, being highly heat sensitive is always filtered to remove any microbes. Heat sensitive materials like beer is sterilized by pasteurization. Hormones are cold-sterilized using gamma-radiation. 

Chloramphenicol binds to 23S rRNA of large ribosomal subunit (50S) to inhibit peptide chain elongation during protein synthesis.

Bird flu is caused by the influenza virus subtype H5N1.

Acidic dyes have negative charge and bind to positively charged cell structures. Its examples includes eosin, rore bengal & acid fuschin.

The tra genes present in the plasmid are responsible for the formation of sex pili & the transfer of chromosomal genes from F+/Hfr/F’ cells to F- cells. The transfer of a copy of resistance plasmid results in the transfer of drug resistance genes as well. Transduction is mediated by virus and their is no role of plasmid in transduction.

In stationary phase the cell size does not increase, it remains same and peptidoglycan cross linking also remains the same in stationary phase as the growth rate of cells nearly equal their death rate.

An episome is that type of plasmid that can exist both, as an independent entity as well as after integrating into the host’s chromosome. They contain tra operon, where genes are responsible for the formation of the sex pili & the transfer of gene. Plasmids are necessary for conjugation (which is a type of horizontal gene transfer)

Cyanobacteria, a group of photosynthetic bacteria can grow easily in a medium exposed to light and air. They perform oxygenic photosynthesis. Some of them are nitrogen fixing in anaerobic conditions but can grow in aerobic conditions. 

Cocci is sphere shaped structure bacteria

For sphere surface area to volume ratio is 3/a 

a = radius of sphere

As per ques, diameter given as 1 µm so radius is 0.5 

Therefore surface area to volume ratio is 3/a= 3/0.5 = 6

Total dilutions = 5mL sample in 45 mL diluent = 1/10 = 10^-1
It is next diluted by1/100 factor. Hence. 10^-3.
Further dilution of 1/100 leads to 10^-5.
Hence, Dilution factor = 10^-5
Volume plated = 0.1 mL
No. of colonies = 137
CFU = ?