30 Questions
What is the primary mechanism of action of certain microbial control agents on the plasma membrane?
Altering its permeability due to damage to lipid and protein components
What is the main difference between antimicrobial and antibacterial compounds?
Antimicrobial compounds are effective against all types of microorganisms, while antibacterial compounds are only effective against bacteria
What is the purpose of commercial sterilization in canned food?
To kill endospores of Clostridium botulinum
What is the effect of Triclosan on microbial populations?
It gives rise to antimicrobial resistance indirectly
What is the primary goal of degerming?
To remove microbes from a limited area, such as the skin around an injection site
What is the effect of certain microbial control agents on cellular proteins?
They damage cellular proteins by breaking hydrogen bonds and covalent bonds
What is the primary mechanism by which moist heat kills microorganisms?
Denaturation of enzymes
What is the term used to describe the lowest temperature at which all microorganisms in a liquid culture are killed in 10 minutes?
Thermal death point
What is the primary advantage of autoclaving over boiling for sterilization?
It is more effective against bacterial spores
What is the purpose of the HTST method of pasteurization?
To destroy pathogens without altering the flavor of the food
What is the term used to describe the absence of significant contamination?
Asepsis
What is the term used to describe the length of time required to kill all bacteria in a liquid culture at a given temperature?
Thermal death time
What is the primary effect of ionizing radiation on water?
Formation of highly reactive hydroxyl radicals
What is the wavelength of UV radiation that is most effective for germicidal purposes?
260 nm
How do microwaves kill microbes?
Indirectly, as materials get hot
What is the effect of refrigeration on microbial growth?
Bacteriostatic
What is the purpose of lyophilization?
To preserve microbial cultures, food, and drugs
What is the characteristic of chlorine as a disinfectant?
Effective against all the test bacteria but more effective against gram-positive
What is the primary factor that limits the growth of bacteria in an environment?
Available nutrients
During which phase of the microbial growth curve do bacteria prepare for binary fission?
Lag phase
What is the result when the number of bacterial cells produced is equal to the number of cells that die?
Stationary phase
What is the purpose of adding 20% glycerol to an agar slant?
To preserve the bacteria for up to 6 years
What is the definition of generation time in microbiology?
The time it takes for a bacterial cell to divide or double in number
What is the relationship between the number of bacterial cells produced and the number of cells that die when a population exceeds the carrying capacity?
The number of cells produced is equal to the number of cells that die
Which of the following factors should be considered when selecting a disinfectant?
Presence of organic matter and temperature
What is the primary purpose of the use-dilution test?
To evaluate the bacterial survival in a manufacturer's recommended dilution
Which of the following acids is used as a food preservative to inhibit fungal metabolism?
Sorbic acid
What is the mechanism of action of aldehydes, such as formaldehyde and glutaraldehyde, as chemical disinfectants?
Denaturation of proteins
What is the primary mechanism of action of ethylene oxide as a sterilizing agent?
Protein denaturation
Which of the following methods is used to evaluate the effectiveness of agents against viruses, endospore-forming bacteria, mycobacteria, and fungi?
Use-dilution test
Test your understanding of microbial growth and the factors that control it, including the carrying capacity and its limitations. Learn how the number of bacterial cells produced and introduced affects the population's growth and death rate.
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