MCQ Bank

Ultraviolet light at a wavelength of approximately 260 nm is strongly absorbed by DNA, causing adjacent thymine bases to covalently link and form thymine dimers. This structural distortion disrupts normal DNA replication and transcription.

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Growth and development of microorganisms are greatly influenced by their ................

A) pH
B) nutrient
C) population size
D) environmental conditions

AI Explanation

Microbial growth and development are broadly and deeply influenced by a combination of various environmental conditions such as temperature, oxygen availability, pH, and osmotic pressure.

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Most of microorganisms contain ___% of water in their cell.

A) 40-50
B) 90-95
C) 20-60
D) 70-80

AI Explanation

Water is the primary constituent of microbial cells, typically accounting for 70% to 80% of their total cellular weight to maintain essential biochemical reactions.

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........... is an indirect method for the estimation of microbial biomass.

A) pour plate
B) plate count
C) spectrophotometry
D) dry weight estimation

AI Explanation

Spectrophotometry measures the optical density or turbidity of a liquid microbial culture, serving as a rapid indirect method for estimating microbial biomass without counting individual cells.

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Liquid and food products are usually processed by ........... in order to reduce pathogenic bacteria.

A) ultra-high temperature treatments (UHT)
B) pasteurization
C) incineration
D) dry heat

AI Explanation

Pasteurization is a thermal processing method commonly applied to liquid and food products to kill pathogenic bacteria and extend shelf life without altering the product's quality.

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_______ rays emitted from the excited nucleus of cobalt 60 generates free radicals, OH• and H•

A) Gamma rays
B) Beta rays
C) Alpha rays
D) Cosmic rays

AI Explanation

Gamma rays emitted from radioactive isotopes like cobalt-60 have high penetrating power and ionize water molecules within cells to generate reactive free radicals such as OH and H.

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Drugs and antibiotics that kill bacteria are known as .............

A) bacteriostatic agents
B) bactericidal agents
C) bacteriophage
D) antibacterial agnets

AI Explanation

Antimicrobial agents, drugs, and antibiotics that actively kill bacteria rather than merely inhibiting their growth are referred to as bactericidal agents.

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Water activity of pure water is__

A) 3
B) 5
C) 20
D) 1

AI Explanation

Water activity is defined as the vapor pressure of a solution divided by the vapor pressure of pure water, making the water activity of pure water exactly 1.

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.........microorganisms grow optimally in temperature range of 20-45˚C.

A) thermotolerant
B) Mesophilic
C) psycrophilic
D) thermophilic

AI Explanation

Mesophilic microorganisms thrive best in moderate temperature ranges typically between 20 and 45 degrees Celsius, which includes most human pathogens.

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Fungi require ...... moisture content as compare to bacteria for their growth.

A) equivalent
B) elevated
C) high
D) low

AI Explanation

Fungi generally possess lower moisture requirements and can tolerate lower water activity levels compared to most bacteria, allowing them to grow on drier substrates.

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Q10

Spontaneous mutation rate is____per generation per gene in most bacterial DNA.

A) 10-5
B) 10-10
C) 10-8
D) 10-3

AI Explanation

The spontaneous mutation rate in bacterial DNA typically ranges between 10^-7 and 10^-11 per generation per gene, with 10^-10 being a standard representative estimate used in microbial genetics.

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Q11

_______ chemical treated cells has the ability to uptake the DNA from surrounding

A) Epithelial cells
B) Competent cells
C) Liver cells
D) Neutrophils

AI Explanation

Cells treated with chemical agents, such as calcium chloride, undergo alterations in their cell wall and membrane permeability, rendering them competent to take up exogenous DNA from their surroundings.

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Q12

The technique which store different strains in liquid nitrogen is called?

A) Stock culture
B) All of these
C) Cryopreservation
D) Lyophilization

AI Explanation

Cryopreservation is the preservation technique used to store different microbial strains and biological materials at ultra-low temperatures using liquid nitrogen.

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Q13

Which of the following enzyme is used to make cDNA from RNA template?

A) Reverse transcriptase
B) DNA gyrase
C) DNA polymerase
D) RNA polymerase

AI Explanation

Reverse transcriptase is an enzyme derived from retroviruses that synthesizes complementary DNA (cDNA) using an RNA template.

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Q14

Genetic engineering already has produced ___________

A) Insulin
B) All of the above
C) Human growth hormone
D) Interferon

AI Explanation

Genetic engineering techniques have been successfully utilized to produce recombinant therapeutic proteins, including human insulin, human growth hormone, and interferons.

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Q15

__________ has often been preferred for industrial applications

A) Methylotrophs
B) None of them
C) P. Angusta
D) Streptomyces

AI Explanation

Streptomyces species are widely preferred and extensively used in industrial biotechnology for the large-scale production of numerous antibiotics, enzymes, and secondary metabolites.

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Q16

In Gram-negative bacteria the secretion is always into the __________

A) Cytoplasm
B) None
C) Periplasmic space
D) Extra embryonic layer

AI Explanation

In Gram-negative bacteria, protein secretion pathways often direct molecules across the inner membrane into the periplasmic space as an intermediate step before reaching the exterior.

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Q17

Most fermentation require liquid media often referred to as _______

A) Semi-liquid
B) Broth
C) None
D) Agar

AI Explanation

Industrial and laboratory fermentations typically utilize liquid nutrient media, commonly known as broth, to support rapid microbial growth and metabolite production.

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Q18

Transformation of ___________ plants can be performed using plasmids derived from soil bacteria

A) None of them
B) Monocotyledonous
C) Both of them
D) Dicotyledonous

AI Explanation

Plasmids derived from soil bacteria such as Agrobacterium tumefaciens are classically and most efficiently used for the genetic transformation of dicotyledonous plants.