The microbial death rate is constant under a particular set of conditions (so it could change with changes in temperature).
Correct Answer: The cells in a population die at a constant rate
The cell wall, plasma membrane, nucleic acids and cellular proteins are all required for bacterial survival.
Correct Answer: All of the choices
Sterilization is the term used for the destruction of all organisms in a particular place.
Correct Answer: Removal of all microbes including endospores
The greater the number of organisms, the longer it will take to kill all of them. The lower the temperature at which the microbes are treated, the longer it will take to kill all of them. The environment in which the microbes to be treated exist is particularly important in health care because many pathogens will be associated with organic materials such as blood, saliva, bodily fluids, or even fecal material, which inhibit the accessibility of the antimicrobial agents to the organisms. Of all the factors that affect the rate of microbial death, endospore formation may be the most important. Endospores are resistant to many of the agents routinely used to inhibit microbial growth, and spore-forming organisms can evade destruction by these agents.
Use-dilution method is more time-consuming than the phenol coefficient and disk diffusion methods, but it can tell you whether an antimicrobial agent is bacteriostatic or bacteriocidal. It uses standardized preparations of certain bacteria.
Correct Answer: The use dilution method
Increasing concentration increases the potency of most chemical agents but it reduces the effectiveness of alcohol as an antimicrobial chemical. Alcohol needs water to kill microbes effectively so 70% strength alcohol is a better disinfectant than 90%.
Correct Answer: Higher concentration
Soap is the least effective antimicrobial agent.
Correct Answer: Soap
Endospores are resistant to almost all disinfectants and antiseptics.
Correct Answer: Endospores
Oxidizing agents are high-level disinfectants and antiseptics that prohibit bacterial metabolism.
Correct Answer: Metabolic pathways
It is not possible to compare the agents unless their concentrations are the same and their rates of diffusion are known. Without this information it is impossible to make a comparison.
Correct Answer: Insufficient information to compare potency
QUATS are quaternary ammonium compounds which destroy the lipid structure associated with the phospholipid bilayer that makes up the plasma membrane of the bacterial cell.
Correct Answer: The plasma membrane
Pseudomonas is very resistant to antibacterial agents so a control agent that can kill Pseudomonas must be potent.
Correct Answer: Kills Pseudomonas
Neutralization refers to the protective mechanism of antibodies and is not connected with controlling microbial growth.
Correct Answer: Neutralization
Irradiation is not a chemical. It is a physical method.
Correct Answer: Ultraviolet irradiation
Pasteurization is used to reduce the overall amount of bacteria, including pathogens. It does not preferentially act on Gram-negative or Gram-positive bacteria and cannot kill endospores. It does not sterilize (kill all microbes) which is why milk eventually spoils even when refrigerated.
Correct Answer: Pathogens
Low temperature will slow but not stop the growth of microorganisms.
Correct Answer: Preserves food for a period of time
Autoclaves are the only choice that can sterilize, the other slow microbial growth or kill only a proportion of organisms. An autoclave is like a pressure cooker and sterilizes objects when steam condenses to liquid water on the objects to be sterilized and the hot water gradually raises their temperature.
Correct Answer: Autoclaving
The pressurized steam used in an autoclave kills endospores.
Correct Answer: Sterilization
Both procedures kill bacteria.
Correct Answer: Both
Pasteurization is the milder treatment.
Correct Answer: Pasteurization
Neither method destroys prions.
Correct Answer: Neither
Ultraviolet light is a form of non-ionizing radiation — it excites atoms but does not ionize them.
Correct Answer: Non-ionizing radiation
Gamma rays are a form of ionizing radiation — they cause electrons to be ejected from atoms.
Correct Answer: Ionizing radiation
DNA is very sensitive to ionizing radiation, and exposure to it causes large scale mutations. Exposure to non-ionizing radiation causes the formation of abnormal bonds, such as thymine dimers, in DNA.
X-rays are a form of ionizing radiation.