Microbiology Test 3 Mr. Hackney
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- Agents that kill microbes or inhibit their growth are known as ________.
- Antimicrobial agents
- The removal or destruction of all forms of microbial live ,including endospores, is called ________.
- Sterilization
- The technique used to kill Clostridium botulinum and it's spores but is not a complete sterilization is called ______.
- Commercial sterilization
- What is sanitization?
- The reduction of micobes that are present to safe levels.
- What is the term given to a technique of controling microbes that actually kills the microbes?
- Microbicidal agent
- What is the practical use of Commercial sterilization?
- A method used to process canned foods.
- What are the three different approaches to controling microbial growth?
- 1)Killing microbes, 2)Preventing microbial growth, 3)Physical removal of microbes
- What is the effect of microbistatic agent?
- As long as the agent is present the growth of the microbe is halted-they inhibit microbial growth.
- Antisepsis is the destruction of vegetative pathogens where?
- On skin and other living tissues.
- Destruction of vegetative pathogens present but does not kill spores is known as ______.
- Disinfection
- What is the term given to the complete absence of microbes from an area?
- Asepsis
- The removal of microbes from an area (such as skin or table)
- Degerming
- A strong, harsh chemical agent used to destroy vegetative pathogens on nonliving surgaces is known as a _______.
- Disinfectant
- What is an Antiseptic?
- A chemical agent that is used to kill vegetative pathogens on living tissue, it is less harsh than a disinfectant.
- Breifly list three reasons for controlling microbial growth.
- 1)prevent food spoilage, 2)prevention of desease by microbes, 3)prevention of microbial contamination and undesirable alteration of materials.
- Of the folowing which is the most resistant to anti microbial agents: Naked virus, endospores, prions.
- prions
- Of the folowing which is the most resistant to anti microbial agents: vegetative protozoa, enveloped viruses, mycobacteria.
- mycobacteria
- Of the folowing which is the most resistant to antimicrobial agents: Gram-positive bacteria, Enveloped viruses, Fungi.
- Fungi
- What is the most resistent pathogen?
- Prions
- What is the least resistant pathogen.
- Enveloped viruses.
- Why do we wash and scrub our hands even we use soap?
- It reduces the concentration of microbes present therefore reducing the concentration of of antimicrobial agent needed.
- Why is it better to use hot water when using a chemical agent?
- Heat generally increases the activity of a chemical agent.
- What are five factors effecting the use of microbial chemical agents?
- 1)type of pathogen 2)number of microbes present 3)concentration of chemical agent 4)Time of exposure 5)environmental conditions
- What is the ideal concentration of a chemical agent and why?
- Lowest effect concentration because it is the most cost effective and the least toxic.
- List some environmental conditions that effect the activity of chemical agents?
- pH, temperature, organic molecules(mucus, fecal matter, blood)
- How does decreasing pH effect the activity of a chemical agent?
- Acidity generally increases activity of chemical agents.
- How is time of expsoure related to activity of chemical agents?
- time os exposure is inversely related to the concentration of the chemical agent and directly related to the number of microbes present.
- Are cold temperatures microbicidal or microbistatic?
- Microbistatic-cold temperature don't kill the microbes they just halt their growth.
- Desiccation is microbicidal. True or False?
- False-desiccation only halts growth.
- What are the three targets by which chemical agents affect microbes?
- 1)cell membranes 2)proteins 3)nucleic acids(DNA)
- What are the targets of phycisal factors that affect microbial growth?
- 1)cell membranes 2)proteins 3)nucleic acids(DNA)
- What effect does exposing microbes to steam heat have and is it microbistatic or microbicidal?
- Steam heat causes cellular components to coaggulate and it is microbicidal.
- Is dry heat microbicidal or microbistatic and how does exposure to it affect microbe?
- Dry heat bakes or oxidizes(burns or incinerates)cell components and it is microbicidal.
- A disinfecting process uing high temperatures to kill all pathogens present in foods is known as _________.
- Pasteurization
- What are the different types of pasteurization?
- 1)classic method of pasteurization 2)high temp short time 3)ultra high temp
- Describe the classic method of pasteurization?
- Exposure substance to 63C for 30 mins
- Explain the difference between the Classic method of pasteurization and the HTST method.
- The HTST method has higher temperatures and shorter times and is considered equivelent methods if they kill all the microbes present.
- Does steam or dry heat kill quicker and how?
- Steam heat kills quicker by penetrating the cellular components and coaggulating then or clumping them together.
- What are equivalent treatments?
- methodes of changing temperature and varyinge exposure times to acquire the same results as the classic method of pasteurization.
- What do we call the minimum time required to kill microbes present in a suspension or liquid at a given temperature?
- Thermal death time
- What is the decimal reduction time?
- the time required to kill 90% of the bacteria present at a given temperature.
- What do we use to kill microbes by producing high-energy free radicals which react with DNA and other components killing microbes?
- Ionizing radiation
- What is a practical use for the killing of microbes by exposing them to ionizing radiation?
- Cold sterilization
- Killing microbes in foods by the use of ionizing radiation is called _______.
- cold sterilization
- What are the two types of filters used to remove microbes and what are the mediums they work on?
- HEPA filters-removes microbes from the air and Membrane filters-that remove microbes from fluids.
- What does HEPA stand for?
- High-Efficiency Particulate Air
- What is the best way to sterilize a heat sensitive fluid
- By using a membrane filter.
- Describe the process of lyophilization.
- Freeze drying of microbial cultures in a vaccum (water is removed by sublimation)
- What is a common way of storing microbes by using both cold temperatures and dessication.
- lyophilization
- What is the term given to the removal of water and it is ti microbicaidal or microbistic?
- Dessication-and its microbistatic
- What are the typical conditions of an autoclave?
- 15 psi. steam pressure at 121C for 15 minutes.
- How does high pressure effect microbial growth.
- It kills them by altering and denaturing their proteins
- List the six methods of physical control of microbial growth?
- 1)heat 2)cold 3)filtration 4)high pressure 5)desiccation 6)radiation
- What are the typical conditions for sterilization with dry heat and what is it used for?
- 170C for 2hrs.-used to sterilize glassware.
- What kind of sterilization do we use to sterilize our inocculation loops in lab?
- Dry heat-incineration-oxidizing of cellular components.
- What is the term given to the physical removal of microbes?
- filtration
- What type of fluids are best suited for filtration rather that pasteurization?
- vitamins and antibacterial fluids that will be destroyed by heat