Micro - Ch. 7

_______________ is a process used to destroy pathogens in food and drinks. It must be done at a lower temperature than other methods so that _______________. autoclaving; the taste of the food or drink will not be altered autoclaving; beneficial microorganisms are not killed Pasteurization; the taste of the food or drink will not be altered Pasteurization; beneficial microorganisms are not killed

During a flood, a community's well water system is contaminated with a pathogenic fungus. If the residents boil their water for 15 minutes prior to consumption, will they be protected? yes, most likely definitely not probably not

Which of the following is an example of microbial control? Select all that apply. Sue washes off the vegetables before serving them in a meal. Mary microwaves food before putting it on the table. Sue uses bleach to clean the kitchen counters. Mary places leftovers in the refrigerator after the meal.

What was the MOST likely source of the family's botulism food poisoning? The family consumed botulism toxin in the chicken. The family consumed botulism toxin in the canned tomatoes. The family consumed botulism toxin in the canned green beans. The family consumed botulism toxin in the spinach salad.

Botulism food poisoning is a preventable illness if special precautions are taken during food preparation. In this case, what could Sue have done to prevent the outbreak of botulism? Select all that apply. Sue noticed that the pressure cooker was malfunctioning during the canning process. She should have fixed the instrument, borrowed a properly working one, or purchased a new pressure cooker. Sue could have lightly heated the food before serving it to her family members. Sue could have boiled the food for at least 10 minutes before serving it to her family members. She could have discarded all of the home-canned food and replaced it with store-bought canned vegetables.

Which of the following best explains why the pressure cooker is so important in the canning process? A pressure cooker utilizes normal atmospheric pressure for longer-than-normal cooking times in order to prevent the growth of microbial contaminants and possible endospores. A pressure cooker utilizes steam to create a higher-pressure environment that allows the food to cook at higher temperatures than normal. The higher temperatures kill most contaminating microbes and endospores and therefore effectively sterilize the food. Pressure cookers utilize temperatures that kill only the pathogenic organisms and leave behind the nonpathogenic ones to enhance the flavor of the food. Pressure cookers utilize pressure and dry heat to create an environment that will remove harmful organisms from the food contents. Dry heat is the most effective method of eliminating endospores.

Use of moist heat can control microbial growth in many circumstances, but heat-sensitive items and those susceptible to moisture cannot be sterilized in this manner. Which of the following correctly describes a method of physical control used to control microbial growth on or in such items? Select all that apply. Filtration is the passage of a liquid or a gas through a screenlike material with pores small enough to retain microorganisms. A vacuum is typically used to force the liquid through the mesh, and then the sterile liquid or gas is collected in a sterile container on the other side. Nonionizing radiation, such as UV light, has a wavelength longer than that of ionizing radiation. The wavelengths of UV light are absorbed by cellular DNA in organisms directly exposed to the light. Desiccation is a process that removes water from microorganisms, leaving them unable to grow or reproduce, but still viable. Osmotic pressure is a process that uses high concentrations of salts and sugars to preserve food.

Sodium nitrate and sodium nitrite are added to many meat products, such as ham, bacon, hot dogs, and sausage. These additives help to prevent the growth of Clostridium botulinum by inhibiting certain iron-containing enzymes of the organism. This is an example of chemical food preservation. Which of the following correctly describes a method of chemical control used to control microbial growth? Select all that apply. Surface-active agents, or surfactants, decrease surface tension among molecules of a liquid. Phenolics exert antimicrobial activity by injuring lipid-containing plasma membranes, which causes the cellular components to leak out of the cell. Alcohols exert their action by denaturing proteins and dissolving lipids. High pressure is used to denature proteins in vegetative cells.

An antimicrobial chemical was added to a population of bacteria. The initial population was 107 living cells (10,000,000). After 2 minutes, only 106 cells still remained alive. After another 2 minutes (4 minutes of total treatment), about how many cells would still be alive? 0 10^3 10^4 10^5

Which of the following best describes why microbial death curves are typically plotted logarithmically? Bacterial population sizes are typically expressed in logarithmic form. Most of the cell death occurs early in the treatment. Different treatments vary in the length of time required to kill all microbes. It takes longer to kill all members of a large population than a smaller one.

Prior to drawing blood for a blood donation, the nurse will clean the arm with a Betadine solution. This form of antimicrobial control is called __________. antisepsis sterilization sanitization disinfection

When microbial control methods are used, microbes are destroyed at a constant rate; there is no instantaneous death of all the microbes present. That microbial death rate is influenced by all of the following factors EXCEPT __________. the number of microbes the microbial characteristics the time of exposure toxins produced by the microbe

Which of the following is the best method to sterilize heat-labile solutions? membrane filtration freezing pasteurization dry heat autoclave

Which of the following chemical agents is used for sterilization? soap alcohol phenolics chlorine ethylene oxide

Which of the following substances is used for surgical hand scrubs? chlorhexidine glutaraldehyde phenol soap chlorine bleach

Which of the following pairs of terms is mismatched? fungicide kills yeasts and molds virucide inactivates viruses sterilant destroys all living microorganisms germicide kills microbes bacteriostatic kills vegetative bacterial cells

The antimicrobial activity of chlorine is due to which of the following? disruption of the plasma membrane the formation of hypochlorous acid the formation of a hypochlorite ion the formation of ozone the formation of hydrochloric acid

Which of the following does NOT achieve sterilization? supercritical fluids dry heat pasteurization autoclave ethylene oxide

Which of the following is a limitation of the autoclave? It cannot be used with heat-labile materials. It requires an excessively long time to achieve sterilization. It cannot inactivate viruses. It cannot kill endospores. It cannot be used with glassware.

An agent used to reduce the number of bacteria on a toilet would most accurately be called a(n) aseptic. antiseptic. virucide. fungicide. disinfectant.

Which of the following disinfectants acts by disrupting the plasma membrane? heavy metals soaps halogens bisphenols aldehydes

Oxidizing agents include all of the following EXCEPT glutaraldehyde. iodine. ozone. chlorine. hydrogen peroxide.

All of the following substances are effective against nonenveloped viruses EXCEPT ozone. chlorine. alcohol. ethylene oxide. None of the answers is correct; all of these are equally effective against nonenveloped viruses.

Which of the following methods is used to preserve food by slowing the metabolic processes of foodborne microbes? freezing nonionizing radiation ionizing radiation lyophilization pasteurization

Which concentration of ethanol is the most effective bactericide? 30 percent 70 percent 100 percent 50 percent 40 percent

All of the following factors contribute to hospital-acquired infections EXCEPT gram-negative bacteria are often resistant to disinfectants. bacteria may be present in commercial products such as mouthwash. some bacteria metabolize disinfectants. invasive procedures can provide a portal of entry for bacteria. None of the answers is correct; all of these factors may contribute to hospital-acquired infection.

The pH of the medium has no effect on the activity of the disinfectant being applied. True False

Moist heat destroys organisms by denaturing proteins. True False

The thermal death time is the time needed to kill all the bacteria in a particular culture at a certain temperature. True False

Any process that destroys the non-spore forming contaminants on inanimate objects is sterilization. True False

Bone and tendons for transplant are decontaminated by plasma sterilization. glutaraldehyde. ethylene oxide. peroxygens. supercritical fluids.

All of the following are methods of food preservation EXCEPT high pressure. desiccation. osmotic pressure. microwaves. ionizing radiation.