Microwave ovens are not reliable for killing microbes in food because ______.
- they do not generate enough heat
- they often heat food unevenly
- microwaves will not penetrate most foods
they often heat food unevenly
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The chemical ortho-_______ provides an alternative to glutaraldehyde because it is less irritating on the eyes. However, it does stain skin proteins gray.
Chlorhexidine solutions are commonly used for ______.
- antisepsis of skin and skin wound care
Which of the following is an advantage of using alcohol solutions for disinfection?
- They do not leave a residue.
- They evaporate quickly.
Ethylene oxide is gaseous agent that ______.
- disrupts cytoplasmic membranes causing cell lysis
- is very useful for sterilizing heat- or moisture-sensitive items
Which of the following chemical classes destroy microorganisms by forming chemical bonds that cross-link and inactivate proteins and nucleic acids?
Why is it important to completely remove all traces of ethylene oxide from items used to grow bacteria?
- Its persistent effect will not allow the microbes to grow.
Chlorhexidine is ______.
Halogens are highly reactive _______ agents that _______.
- oxidizing; cause mutations in DNA
Aqueous solutions of ethyl or isopropyl alcohol are commonly used as antiseptics and disinfectants because they ______.
- are relatively inexpensive
- do not leave a residue
- quickly kill vegetative bacteria and fungi
- evaporate quickly
- are relatively non-toxic
Which of the following are advantages of using ionizing radiation for sterilization?
- Can be used on heat-sensitive material
- Effectiveness at killing pathogens
- Can be used after packaging
Radio waves, X-rays, microwaves, UV light and gamma rays are all examples of ______.
- electromagnetic radiation
Which of the following are effects of ionizing radiation on food products?
- Changes in flavor of some foods
- Killing of bacterial pathogens
Which cellular component is damaged by UV radiation?
UV radiation is used extensively to destroy microbes in ______.
- the air
- drinking water
- food items
Microwaves always cook foods and kill microbes effectively.
A disadvantage of using ionizing radiation to sterilize food is ______.
High pressure (130,000 psi) is thought to kill microbes by altering their ______.
Ionizing radiation is not an effective method of controlling microbes in food products.
Germicidal chemicals ______.
- are often poorly understood with regards to mechanisms of action
- usually react irreversibly with proteins, DNA, cytoplasmic membranes, or viral envelopes
Manufacturers of germicidal chemicals must register with either the FDA and EPA in order to document ______.
- the potency of their product
What are the main limitations of using UV radiation?
- High heat requirement
- Safety of use
- Production of toxic substances
- Poor penetration
Choosing which germicide to use is not that complicated since we only consider how effective it is against the target microbes.
Germicides are generally somewhat toxic to humans and the environment.
Although generally less reliable than heat, germicidal chemicals are especially useful for treating ______.
- heat-sensitive items
- large surfaces
Many germicides lose their effectiveness in the presence of ______.
______ destroy all microbes, including viruses and endospores.
It is often difficult to choose which germicide to use because often the most effective options ______.
_______ can kill all vegetative bacteria (including mycobacteria), as well as fungi and most viruses. This group of germicides is used to disinfect non-critical instruments such as stethoscopes.
- Intermediate-level disinfectants
Where would it be acceptable to risk using an effective germicide that is somewhat toxic to humans?
Aqueous solutions of alcohol at a concentration of ______ are more effective than 100% alcohol.
The effectiveness of germicidal chemicals depends upon ______.
- the concentration used
- the presence of organic matter
Aldehydes typically kill microbes by ______.
- altering proteins
- altering nucleic acids
How do aqueous solutions of alcohol usually affect microbes?
- by damaging lipid membranes
- by denaturing proteins
A tincture is a(n) _______-based solution of an antimicrobial chemical, and it can be more effective than the corresponding aqueous solution.
_______ is used to kill bacteria and inactivate viruses in vaccines. It can also preserve biological specimens.
A 2% solution of ______ is used as a liquid chemical sterilant for treating heat-sensitive medical items.
All of the following are characteristics of bleach, a solution of sodium hypochlorite, EXCEPT ______?
- it is only effective against a limited range of microorganisms
What are characteristics of chlorine when used to disinfect drinking water?
- It is effective even at very low levels.
- It kills many pathogens.
The gaseous agent ethylene oxide is typically used to sterilize all of the following EXCEPT ______.
One of the advantages of chlorine dioxide over other chlorine-releasing compounds is that ______.
- it does not react with organic materials to form toxic products
Chlorine-releasing compounds such as sodium hypochlorite (bleach is a 5.25% solution) are used for all of the following EXCEPT ______.
- wound treatment and skin cleansing
Which of the following are disadvantages of using chlorine to disinfect drinking water?
- At the levels used, it does not kill Cryptosporidium parvum oocysts and Giardia lamblia cysts.
- It is irritating to skin and mucous membranes of the consumer.
- Organic material disrupts its germicidal activity.
- It reacts with some organic compounds to form potential carcinogens.
A strong oxidizing agent increasingly being used as a disinfectant and sterilant for treating drinking water, wastewater, and swimming pools is ______.
Of all the metals, ______ is one of the few still used as a disinfectant.
Which metal compound is used as a disinfectant in burn creams and bandage pads?
Metal compounds typically kill microbes by ______.
- inactivating enzymes and other proteins
Hydrogen peroxide and peracetic acid are powerful ______ agents.
The effectiveness of hydrogen peroxide as a germicide on living tissue like wounds is reduced because ______.
- our catalase enzymes quickly break it down
Silver is used as an antimicrobial in which of the following products?
Hot solutions of hydrogen peroxide are often used as a sterilant ______.
- to produce juice and milk containers
- is a strong oxidizing agent
What are advantages to the use of peracetic acid as a germicide?
- It is even more potent than hydrogen peroxide.
- It leaves behind no residue.
- It can be combined with hydrogen peroxide to sterilize items in less than an hour.
Peroxygens are powerful oxidizing agents that ______.
- include hydrogen peroxide and peracetic acid
- can be used as sterilants under controlled conditions
Phenolics are ______.
Hydrogen peroxide is a more effective germicide on ______.
Phenolic compounds are effective against ______.
- most vegetative bacterial cells
Which of the following statements about vapor-phase H2O2 is true?
- It is more effective than liquid solutions and can be used as sterilant.
______ detergents are more effective as germicides than ______ detergents because their positive charge attracts them to negatively charged microbial cell surfaces.
What are limitations to the use of the peroxygen peracetic acid?
- It has a sharp, strong odor, and it irritates the skin and eyes.
Quaternary ammonium compounds (quats) are Blank______.
The act of delaying spoilage is ______.
What is the active ingredient in Lysol?
Adding sorbic, propionic, and benzoic acid to foods affects ______ of microbes.
Phenolics kill microorganisms by ______.
- denaturing proteins
- destroying cytoplasmic membranes
The addition of nitrates and nitrites to processed meats is aimed at preventing germination of the endospores of _______.
All of the following are advantages of quaternary ammonium compounds (quats) EXCEPT they ______.
- are neutralized by cationic soaps and gauze
Consider the use of low temperature storage for the preservation of food. Which of the following are accurate statements?
- Refrigeration inhibits the growth of many pathogens and spoilage microorganisms by slowing or stopping critical enzyme reactions.
- Psychrotrophic and some psychrophilic microorganisms can grow at refrigeration temperatures.
Cationic detergents typically work by ______.
- disrupting the cell membrane
A high-solute environment damages microbial cells by causing ______.
Which of the following are used as preservatives by creating an environment that will draw water out of cells, dehydrating them?
Adding preservatives such as benzoic acid to food is important because ______.
- it inhibits growth of many bacteria and mold
Nitrates and nitrites added to processed meats may be converted to carcinogenic ______ by the metabolic activities of intestinal bacteria or during cooking.
There is no risk of food poisoning with dried food since drying kills all microorganisms associated with the food.
The main effect of low temperature storage is to ______.
- slow the activity of microbes
Salting and drying decrease the availability of water in food, resulting in an environment that is ______ relative to microbes, thereby preventing their growth.
Adding large amounts of salt and sugar to foods ______.
- dehydrates microbes and prevents their growth
The process of preserving food by rapid freezing followed by drying in a vacuum is called _______.
Cases of salmonellosis have been traced to dried eggs. This demonstrates that ______.
- drying is not a reliable way to kill all microbes
A very important difference between innate and adaptive immunity is the ability to change the response over time to a stronger, faster, better response in the adaptive system.
Phagocytes were first reported in ______.
Innate immunity includes ______.
- first-line defenses
- sensor systems
- effector actions
The immune system must destroy pathogens while maintaining ______.
All of the following are characteristics of the innate immune response EXCEPT ______.
- the capability to shorten response time and increase strength of response upon repeated exposures with the same antigen
Pattern recognition receptors (PRRs) are generally found ______.
- on the surface of innate immunity cells
- within the endosomes/phagosomes of innate immunity cells
The effector actions of innate immunity ______.
- eliminate invaders
- sense the presence of invaders
- physically prevent microbes from invading
The ______ response of innate immunity is a coordinated response involving other effector actions.
The deeper interior tissues of the body are generally laden with helpful symbiotic bacteria.
The first-line defenses of innate immunity are ______.
First-line defenses ______.
- are generally barriers such as the skin or mucous membranes
The exposed surfaces of the body are lined by ______ cells.
Pattern recognition receptors ______.
- bind to compounds unique to microbes yet commonly found on them
Due to its dense layering of tightly joined cells, the skin ______.
- provides a highly efficient barrier that prevents microbes from entering our deeper tissues
The "security teams" of innate immunity that eliminate the invader are the ______.
With respect to the body's borders, the contents of the digestive tract are ______.
What is the main difference between the barrier provided by the skin and the barriers provided by mucous membranes?
- Skin is generally dry (microbes slough off with the topmost layer of cells), while mucous membranes are wet (microbes are washed away by mucus).
The epithelial cells that line the exposed surfaces of the body are tightly packed together and rest on the ______ membrane.
Peristalsis in the intestines is the _______.
- rhythmic contractions of muscles in the intestine to propel food, liquid, and microbes along (and ultimately out) of it
When microbes attempt to attach to the outermost surface of the skin, there is a simple mechanism that prevents an infection from occurring. This simple mechanism ______.
- occurs as the cells continuously flake off, taking with them any attached microbes
Lysozyme, an enzyme that degrades peptidoglycan in bacteria, can be found ______.
- in tears
- in phagocytic cells
- in saliva
- in the mucus of the small intestine
Peroxidase enzymes can be found in phagocytic cells.
Which of the following areas have a mucous membrane lining?
- The genitourinary tract
- The digestive tract
- The respiratory tract
The mucociliary escalator's function in the respiratory tract is to ______.
- move microbes and other material trapped in the mucus up and out of the tract
Lactoferrin is ______.
- a protein that binds iron
Lysozyme breaks down peptidoglycan, a common component of the cell wall of bacteria. What effect would this have on most bacterial cells?
- It would leave cells susceptible to lysis due to osmotic pressure imbalances.
All of the following statements regarding antimicrobial peptides are true EXCEPT they ______.
- are long chains of amino acids several thousand amino acids long
People with vitamin D deficiency are more susceptible to certain diseases. This might be related to the observation that the vitamin regulates the expression of some ______.
- antimicrobial peptides (AMPs)
Catalase, an enzyme produced by some species of bacteria, ______.
- breaks down hydrogen peroxide
- creates H2O and O2 as breakdown products
Transferrin can be found ______.
- in saliva, milk, mucus
- in blood and tissue fluids
The normal microbiota competitively excludes pathogens by ______.
- consuming available nutrients that could otherwise support the growth of pathogens
- covering binding sites that might otherwise be used for attachment by pathogens
Lactoferrin can be found ______.
- in saliva, milk, and mucus
All members of the normal microbiota live in complete harmony with all other microbes.
Defensins create pores in bacterial cytoplasmic membranes, leading to leakage of ions and fluids and resulting in bacterial death.
Antibiotics disrupt the normal microbiota and can predispose a person to infections caused by ______.
- Clostridioides difficile growing in the intestine
- Candida albicans growing in the vagina
Exposure to members of the normal microbiota allows the immune system to "learn" to distinguish harmless microbes from pathogens. Failure to do this can result in ______.
- overgrowth of Candida albicans in the vagina
- pseudomembranous colitis caused by Clostridioides difficile
- chronic inflammatory conditions
Some areas of the body have populations of microbes living on cell surfaces. Select each area that would have normal microbiota.
- Large intestine