Microbiology with Diseases by Taxonomy Chapter 9 Answers

Microbiology with Diseases by Taxonomy Answers

Microbiology with Diseases by Taxonomy Chapter 9 Answers 1CM
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Microbiology with Diseases by Taxonomy Chapter 9 Answers 1CT
The antimicrobial agents used for longevity of sandwich:
Explanation
Grilled cheese sandwich is a diary product, which attract microorganisms quickly, if necessary precautions are not taken. The supplier had stored the sandwich in an air tight box for ten years without decay or the growth of mold by using antimicrobial chemical.

The chemical agents include nisin and natamycin that reduce the growth of bacteria and fungi in cheese.
The physical agent he used for preservation is ultra high temperature sterilization of moist heat that denatures proteins and destroys membranes of microbes.
Desiccation is also used for preservation and inhibits the metabolism of organisms.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 1MC

Sterilization can eliminate harmful microorganisms but hard to eliminate viruses as they do not have protein coat to sterilize.
The process of sterilization needs destruction of the protein coat and eventually killing the organism.
Hence, the option (b) is incorrect.
Sterilization cannot eliminate prions as they are one of the viral particles that lack protein coats.
Hence, the option (c) is incorrect.
Sterilization cannot eliminate hyperthermphiles because these organisms can tolerate high temperatures. So, this process cannot work on these organisms. Hence, the option (d) is incorrect.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 1SA
Resistance is the condition where microorganisms remain normal even in the presence of antimicrobial drugs and unfavorable environments. These adverse effects can show no negative effect on those resistant microorganisms.

Some bacterial endospores:
These are the most resistant forms of life; they can survive in unfavorable conditions for several years. They can survive for more than 20 years in 70% alcohol. Endospores of Bacillus and Clostridium species are resistant forms.
Mycobacterium species:
These organisms can survive by their waxy cell wall (mycolic acid) in dry conditions and also can survive against most water based chemicals and drugs. The mycolic acids present in their cell walls made them resistant to the adverse condition.
Cysts of some protozoa:
Protozoan cyst walls prevent the entry of disinfectants and protect them from drying and heat.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 2CT
Antimicrobial effect of desiccation when grapes are dried in sun:
Explanation
Desiccation is a physical method of microbial control, which inhibits metabolism of microbes by killing them. Moreover, desiccation is the only method, which has antimicrobial effect operating when grapes are dried in the sun to make raisins. That is why dried food can be stored longer without any contamination. Sometimes, UV light can also kill microbes and fungi. The sugar, which is present in grapes are stable without any contamination when it is dried.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 2MC

Antiseptics are the antimicrobial substances that reduce the effect of infection of living tissues or skin. Hence, the option (a) is incorrect.
Degermers are the antigermal substances that kill harmful germs as well as beneficial germs. Hence, the option (c) is incorrect.
Pasteurization is a process that is used for heating the food products, which are found in liquid state for a fixed length of time. Hence, the option (d) is incorrect.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 2SA
Phenol coefficient:
It is the oldest method in which efficacy of various disinfectants and antiseptics are evaluated by calculating the ratio of agent’s ability to control microbes to that of phenol under standard conditions. If phenol coefficient is greater than 1, it indicates that the disinfectant is more effective than phenol; and the larger ratio indicates that the disinfectant is more effective.
Kelsey-Sykes capacity test:
It determines the capacity of a given chemical to inhibit bacterial growth. Here bacterial suspension is added to a chemical then the turbidity is observed. If there is lack of turbidity then there is lack of bacterial growth. Turbidity in the medium indicates that bacteria got survived.
In-Use test:
It is a more realistic method for determining efficacy of a chemical, even though it is more time consuming. It checks the real lives situations in which swab from a suspected site are grown on a media and check for growth.
Use-Dilution test:
This test measures efficacy of detergents and antiseptics against specific microbes. In this test, several metal cylinders are dipped into broth culture of bacteria and dried at 37^oC. Now each contaminated cylinder is dipped into different dilutions of detergents and antiseptics, later incubated in a sterile medium for 48 hours. The most effective agent is the one that entirely prevents microbial growth at the highest dilution.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 3CT
D value is defined as reduction time in decimal reduction, which is necessary to destroy 90% of microbes in a sample. This value differs with the organism.
The given D value used in the assay of 3 minutes:
100 trillion bacteria (10¹⁴) should get reduced to 10 viable cells; so, there should be reduction of 13 folds to produce 10 viable cells from (10¹⁴).
Thus, 3×13 gives 39 minutes.
Hence, it takes 39 minutes to reduce a population of 100 trillion bacteria to 10 viable cells.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 3MC

Antisepsis is the process to destroy disease causing microorganisms to prevent infection. Hence, the option (b) is incorrect.
Sterilization is the process to remove microbial forms like bacteria, fungi, and viruses, and spores. Hence, the option (c) is incorrect.
Sanitization process removes pathogens from the objects, places, and utensils used by the public to reduce the number of pathogenic microbes to meet public health standards. These standards vary among governmental jurisdictions. So, sanitization best describes the disinfecting of cafeteria plates. Hence, the correct option is (d) sanitization.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 3SA
Mycobacterium tuberculosis causes tuberculosis. The cell wall of these bacteria comprises of lots of waxy lipids and mycolic acids, which allow bacteria to survive against dry conditions. These waxy lipids and mycolic acids also protects these microorganism from most water based chemicals and drugs. Hence, it is highly essential to use strong disinfectants in areas exposed to tuberculosis patients.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 4CT
Reduction of potential pathogenic bacteria in hospitals:
Explanation
The hospital personnel should follow the sterilization procedures by using disinfectants. Additionally, disinfectants reduce the spread of pathogens and destroy most of the microorganisms and viruses on non living tissues like cotton blends of scrub suits, clothes of nurses, lab coats, computer keyboard etc.
The widely used disinfectants are as follows:

Phenolic.
Alcohols.
Aldehydes.
Soaps.

Thus, using strong disinfectants can destroy pathogenic bacteria and fungi, which include strains of Enterococcus, staphylococcus, candida, and aspergillus.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 4MC
Microbial death is a permanent loss of reproductive capacity of pathogens or microorganisms. The rate of microbial death evaluates the efficacy of an antimicrobial agent, which will not simultaneously kill all cells rather; they kill in a constant percentage of cells over time. This is usually a constant value for a particular microorganism over time and particular set of conditions. So, the rate is used to measure the efficiency of a detergent, an antiseptic and efficiency of sanitization technique.
Hence, the correct option is (d) all of the above.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 4SA
Warm disinfectants work better than cool ones, because they have better penetrating power with heat and the chemicals can react faster at higher temperatures. So, they can remove microbes that are present in that area by better penetration due to heat. For example, microbial death rate is high at higher temperatures. If a disinfectant kills same number of microorganisms, it requires 4 minutes at 45⁰C, but 12 minutes at 20⁰C.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 5CT
The following treatments and precautions are taken by growers and consumers:
Explanation
Salmonella enterica causes salmonellosis (severe diarrhea) in US, which is an outbreak. USFDA (US Food and Drug Administration) revels, the food that is contaminated is a component in fresh salsa like raw tomatoes, jalapeno peppers, Serrano peppers. Moreover, Salmonella can enter through broken tomatoes and leaves, so growers and packers should take care while growing and packing. Water should not be contaminated with the bacteria. Consumers should wash the stuff in running water before using or eating. Washing hands also is necessary before eating.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 5MC
An ideal antimicrobial agent should be inexpensive, fast acting and stable during storage. These agents alter the membranes and cell wall and damage nucleic acids and proteins of the animal. These agents act mainly on nucleic acids and produce fatal mutations.
Furthermore, these agents should not be harmful to humans, animals and objects and should control growth and reproduction of all microorganisms.
Hence, the correct option is (d) all of the above.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 5SA
Gram-positive bacteria has thick peptidoglycan layer when compared with gram-negative bacteria. Gram-negative has outer lipopolysaccharide, which contains lipids. The lipids can be easily dissolved at higher temperature and they cannot stand as protective covering. So, gram-negative bacteria are more susceptible to heat than gram-positive bacteria. The gram-negative bacteria are not only susceptible to heat, but also to various antibiotics and disinfectants.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 6CT
Medicated over-the-counter foot powder action against fungi:
Explanation
Over-the-counter foot powder is mediated. Moreover, the powder contains the element zinc oxide, which is proven to have antimicrobial activity. Additionally, over-the-counter medicated foot powder contains camphor, eucalyptus oil, lemon oil, and zinc oxide. It also inhibits the growth by affecting cellular functions and causes deformation in fungal hyphae.
Thus, camphor, eucalyptus oil, and lemon oil are considered as inactive ingredients in the preparation.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 6MC

Salmonella enterica is a flagellated, gram-negative bacterium. They cause a disease, salmonellosis, which is carried by infected food products. These organisms do not have any biological significance. Hence, the option (b) is incorrect.
Mycobacterium tuberculosis is a pathogenic causative agent that causes tuberculosis. These bacterium need oxygen to survive, they cannot live in high extreme temperatures. Thus, they are biologically insignificant. Hence, the option (c) is incorrect.
Staphylococcus aureus is a bacterium, which is generally found on the human skin and respiratory tract. Hence, the option (d) is incorrect.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 6SA
There are different methods to control microorganisms. Those methods are classified as physical methods and chemical methods. Some of the physical methods to control microorganism are as follows:

Moist heat:
This method kills cells by denaturing proteins and destroying cytoplasmic membranes. It is used to sterilize chemicals and to disinfect and sanitize different objects. Example: Disinfecting baby bottles
Dry heat:
Hot air is used to denature proteins and foster oxidation of metabolic and structural chemicals. It requires high temperatures for longer times than moist heat, because it penetrates more slowly.
Refrigeration and Freezing:
It halts the growth of most pathogens because chemical reactions occur slower at lower temperatures. It is used in food preparation and storage.
Ionizing radiation:
It denatures the DNA (deoxyribonucleic acid) molecules, which are mutated and responsible for cell death.
Osmotic pressure:
It uses high concentrations of salt or sugar in foods to inhibit microbial growth. The removal of water inhibits cellular metabolism because enzymes are fully functional only in aqueous environments. These are used to preserve foods like salted fish.
Desiccation and Lyophilization:
It is the technique, which combines both freezing and drying. It inhibits metabolism and is used for long term storage of bacterial cells and for preservation of foods.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 7CT
Communicable diseases are common after any natural disaster had occurred. The diseases have increased risk of waterborne illnesses. The disease of water born includes cholera, typhoid, and hepatitis A, E.
The following steps are taken by the people to lessen the spread of waterborne diseases of cholera include:

The primary and healthcare services are to be accessed to bring water safe.
Diseases such as epidemic-prone diseases are detected in the areas affected.
The priority of the communicable disease can be detected for inclusion in the surveillance system. In addition, the need for immunization and vector-control campaigns are arranged.
Antimicrobial drugs stocks of rehydration fluids for vaccines and cholera patients are sent to affected area.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 7MC

Phenol coefficient is measurable scale that provides information about the bacterial activity of a chemical compound with respect to phenol. This measurable scale provides information on comparable activity but not the accurate activity of the bacteria. Hence, the option (b) is incorrect.
Filter paper test is a test paper that is used to filter bacteria with help of a semi-permeable paper. It can be used by placing perpendicularly to an air or liquid flow. This test is dependent on various other factors to get accurate results. Some of the factors like porosity, wet strength, retention of the particles, compatibility, capacity, flow rate etc. Hence, the option (c) is incorrect.
In-use test is performed by the company that manufactures an antimicrobial cleaner for kitchen. It provides an accurate determination of efficacy under real life conditions although it is time consuming process. Hence, the correct option is (d) In-use test.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 7SA
Thermal death point is the lowest temperature that kills all cells in the broth within 10 minutes, whereas thermal death time is the time that it takes to completely sterilize a volume of liquid at a set temperature. It determines the time required by the drug or disinfectant, to completely sterilize the liquid at a particular temperature. In reality, this method was developed for sterilizing canned foods, but they were found to be more useful even for sterilizing pharmaceutical and cosmetic products.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 8CT
Commercial use of antiseptics and disinfectants:
Explanation
Americans are preoccupied with antisepsis and disinfection, as evidenced that every product contains antiseptics and disinfectant chemicals. Moreover, hand soap, shampoo, toothpaste, hand lotion, and deodorants contain antiseptics. Additionally, cutting boards, scrubbing pads, children toys, and laundry detergents also contain disinfectants. So, extensive use of such products adds to human and animal health, but it promotes the development of strains of microbes that are resistant to antimicrobial agents because the susceptible cells die and resistant cells remain to proliferate.
Hence, widespread commercial use of antiseptics and disinfectants has hurt rather than helped American health.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 8MC

An incinerator is combustion vessel or chamber, which is used for treating waste materials or products. These vessels cannot serve the purpose of holding pressure for longer periods. Hence, the option (b) is incorrect.
A desiccator are sealable enclosures that contain desiccants, which are used to protect or preserve such items that are moist-sensitive. They do not work as autoclaves. Hence, the option (c) is incorrect.
A pressure cooker works like an autoclave because it maintains the same temperature and pressure and also it works with the same principle as autoclave works. Steam sterilizes the contents of an autoclave when it is maintained temperature 121 0C and pressure 15 psi for 15 min. Hence, the correct option is (d) a pressure cooker.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 8SA
Pasteurization is a method of heating foods to kill pathogens and control spoilage without altering the quality of food. Pasteurization allows thermophilic and thermoduric bacteria to survive (not pathogenic), but Sterilization eradicates and kills all microbes. So, “Pasteurization is not sterilization.”

Microbiology with Diseases by Taxonomy Chapter 9 Answers 9CT
Quaternary compounds of ammonium are not active against Mycobacterium tuberculosis :
Explanation
Quaternary ammonium compounds or quats are the surfactants, which act by disrupting the cellular membranes so that affected cells lose essential internal ions like potassium ions. They are bactericidal, mostly against gram positive bacteria. In contrast, the agents are not effective against non-enveloped viruses like mycobacterium (Mycobacterium tuberculosis). Thus, contain large amounts of waxy lipids, so it allows the bacteria survive in drying and protect them from most water based chemicals.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 9MC

Lyophilization is a dehydration process, which is used to preserve sensitive materials or perishable material. In another terms, it is also known as freeze-drying. This process is used to prepare the perishable material to transport in a convenient way. Hence, the option (b) is incorrect.
Beef jerky can be preserved from microbial growth by desiccation or drying. In this process the water in the meat gets removed there by it inhibits the metabolism of microorganisms thereby used for preservation of beef jerky for long time.
Hence, the correct option is (c) desiccation.
Radiation is a process that uses energetic particles or waves to kill organisms. These are harmful to biological systems. Hence, the option (d) is incorrect.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 9SA
Desiccation:
It is the state or condition of extreme drying. It inhibits growth of the microorganism by completely removing the water that microbes need for their metabolism. It is also called drying and is mostly used for preservation of foods. The desiccants are the substances that involve in desiccation and they are hygroscopic in nature.
Lyophilization:
This process is otherwise called freeze-drying or cryodesiccation, as it uses freezing and drying procedures to preserve microbes for many years. This is a long term preservation method among the different microbial culture methods known. Dehydration is the typical principle even in this process.
Differences between Lyophilization and desiccation:

Lyophilization is used to preserve different strains of the microorganisms, while desiccation is used to eradicate microorganisms from an area.
Lyophilization process is used for the cells that are sensitive to heat and contain very delicate structures, whereas desiccation is used against all cells.
Very less or no harm occurs to the microbes in Lyophilization, whereas cells will be harmed greatly in desiccation.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 10MC

Visible light waves are those ranges of waves where all objects are visible for a human or animal naked eye. These waves are not harmful and do not have ability to harm organisms. This is not used for antimicrobial technique. Hence, the option (b) is incorrect.
Radio waves are lengthy waves that travel longer distances. They do not effect organisms, as they are less intensive to make harm. This is not used for antimicrobial technique. Hence, the option (c) is incorrect.
Microwaves are highly intensive infrared rays that can pass through any object. They are highly penetrative and harmful to living organisms, if exposed to external environment. This is not used for antimicrobial technique. Hence, the option (d) is incorrect.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 10SA
Halogens, alcohols, and oxidizing agents are the different agents used for controlling the growth of microorganisms. They have different actions on the microorganisms.

Alcohols:
They denature proteins and disrupt cell membrane. These are intermediate-level of disinfectants. They are also used as antiseptics before injections. The proteins treated with alcohols cannot fold properly and cannot function. As a result, the cells will die.
Example: Ethyl alcohol
Halogens:
They denature proteins and kill microbes present in water or on medical instruments or skin. These are also intermediate-level of disinfectants.
Examples: iodine, chlorine, bromine, and fluorine.
Oxidizing agents:
These denature proteins by oxidation. They release oxygen free radicals, which are toxic to microbes and some anaerobes. These are high-level disinfectants.
Examples: hydrogen peroxide, per-acetic acid, and ozone.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 11MC

Phenols are intermediate to low level disinfectants. They can disrupt cell membrane and denature proteins. They are more effective against aerobic microorganisms rather than anaerobic microorganisms. Therefore, the option (a) is incorrect.
Silver, which is a heavy metal ion, can act as antimicrobial agent. It has the ability to combine with sulfur atoms present in cysteine molecules, thereby denaturing the proteins. They are more effective against aerobic microorganisms rather than anaerobic microorganisms. Therefore, the option (b) is incorrect.
Ethanol has bactericidal, fungicidal, and virucidal properties. They are regarded as intermediate level disinfectants. They are very much effective against aerobic microorganisms, rather than anaerobic microorganisms. Therefore, the option (c) is incorrect. Hence, the correct answer is option (d) hydrogen peroxide.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 11SA
Hyperthermophilic prokaryotes are viable in canned goods after post sterilization:
Explanation
Autotrophically growing green non-sulfur phototroph, utilize H₂ (hydrogen) or H₂S (hydrogensulphide) as electron donors. The organism carries out hydroxypropionate pathway by reducing two molecules of CO₂ to glyoxylate; for instance, Chloroflexus. Hydroxypropionate is a three carbon compound and is vital intermediate in hydroxypropionate pathway. Apart from Chloroflexus many hyperthermophilic archaea like Metalosphaera, Sulfolobus, and Acidianus carry out hydroxypropionate pathway. These are non-phototrophic organisms, which are present near the base of Archaea in the phylogenetic tree. Therefore, hydroxypropionate pathway roots are very deep. Besides, hyperthermophilic prokaryotes survive at high temperatures and environmental conditions like acidity or radiations.
Therefore, hyperthermophilic prokaryotes remain viable in canned goods after commercial sterilization because the microbes grow at 85^oC, but not at 37^oC where the food is stored. So, this situation doesn’t create any problem to consumers.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 12MC

Aseptic means an environment or a procedure, which is free of pathogenic contaminants. Aseptic will best describe a surgical procedure that is free of microbial contamination. Another example is vegetables and fruits packed in aseptic conditions. They are completely free of microorganisms. Therefore, the option (d) is correct.
Disinfection is the use of different chemical and physical agents as disinfectants. They include heat, alcohol, ultraviolet light, bleech, etc. They have the ability to inhibit microorganisms, but they cannot ensure that all microbes are destroyed and the surface is free of them. Therefore, the option (a) is incorrect.
Sanitization is the process of disinfection in public places like restaurants. The places and utensils that are utilized by large number of people are sanitized rather than disinfected. Even this process of sanitization cannot ensure the complete destruction of microbes. Therefore, the option (b) is incorrect.
Degerming is a process of removing microbes by scrubbing. For instance, when we wash our hands we degerm our hands. Similarly, nurses before injecting, they degerm that particular area by scrubbing with cotton and alcohol. Even this process cannot ensure complete destruction of microbes. Therefore, the option (c) is also incorrect option. Hence, the correct answer is option (d) aseptic.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 12SA
Alcohols are very effective in 70% solution than 100%:
Explanation
Alcohols in cell membrane facilitate diffusion and are effective. 70% alcohol is used as antiseptic when compared to 100% alcohol; since, 70% alcohol facilitates coagulation of protein. Besides, 100% solution causes protein to harden on exterior side of organism. It causes the microorganism to be dormant, but does not lead to death. Thus, 100% alcohol will dry the bacteria, but it will not kill so, in general 70% alcohol is used.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 13MC

The Center for Disease Control and Prevention has established biosafety guidelines in microbiological laboratories. BSL-3 is a third level of biosafety, in which there is entry through double sets of doors and ventilation, so air moves into the room through an open door. Air leaving will be HEPA filtered (High-efficiency particulate air) before being discharged outside the room. Therefore, the option (a) is the correct answer.
Pressurized suits and showers in entryways are facilities provided under biosafety level 4. They are not considered under BSL-3. Therefore, the option (b) and (c) are incorrect. Option (d) is incorrect, as only one of the given options that is (a) is correct.
Hence, the correct answer is option (a) double sets of entry doors.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 13SA
Action of quats and soaps:
Explanation
Soaps and quats are surfactants, soaps do not kill microorganism, they will wash off the surfaces, but quats disrupt cellular membrane where the affected cell lose internal ions. In contrast, soaps have hydrophobic end, which have fatty acids and hydrophilic end which is negatively charged. Thus, quats are composed of an ammonium cation in which the hydrogen atoms are replaced by other functional groups.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 14MC

Decimal reduction time (D) is the time required to destroy 90% of the microbes in a sample. So, in a sample of E. coli, which has been subjected to heat (lowest temperature) for a specified time, 90% of the cells has been destroyed. So, decimal reduction time will best describe this event. Therefore, the option (c) is correct.
Thermal death point is the minimum temperature, which can kill all the microbes in 10 min. Therefore, option (a) is incorrect. Thermal death time is the time required to completely destroy the microbes in a particular volume of liquid at a particular temperature. Therefore, the option (b) is also incorrect. Option (d) is incorrect as one of the given options is correct.
Hence, the correct option is (c) decimal reduction time.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 14SA
Advantages and disadvantages of using ionizing radiation in food sterilizing:
Explanation
Radiations from electron beams, gamma rays, and X -rays have shorter than 1nm ionizing radiations.
The advantages of using ionization radiations are killing microbes, larvae, and eggs. In addition, it also kills cells that spoil or over ripen fruits and vegetables.
The disadvantages of using ionization radiation are causing of cancer, change taste, and nutritional value of fruits and vegetables.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 15MC

Carbolic acid, which is otherwise named phenol, has corrosive properties. Its vapors are corrosive to skin, eyes, and respiratory tract. Repeated exposure to such vapors can lead to dermatitis and even third degree burns. Therefore, option (a) is incorrect.
Glutaraldehyde, though it is not carcinogenic, it is highly toxic and acts as strong irritant. Therefore, the option (b) is incorrect.
Formalin is a human carcinogen. Exposure to formalin will badly affect the health of a person exposed. Ingestion of formaldehyde will cause death of the person. Thus it is highly toxic to humans. Therefore, the option (d) is incorrect.
Hydrogen peroxide is least toxic to humans and is less irritant. It can cause poisoning only when a large amount of liquid comes in contact with eyes and lungs. If poisoned the symptoms like abdominal pain, body aches, temporary change of the skin color etc are observed. These symptoms are not lethal or toxic. Hence, the correct option is (c) hydrogen peroxide.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 15SA
Camper’s remove pathogenic protozoa, bacteria, and viruses in stream water:
Explanation
Water in streams look clean, but have harmful pathogens in water. The pathogens include bacteria, protozoa, and virus. However, the microorganisms in water cause fever and nausea. The infections can be inhibited by short term treatment; for instance, campers. In addition, iodine tablets and drops of chlorine to 2 liters of water can treat stream water to remove pathogenic protozoa, bacteria, and viruses.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 16MC

Ethylene oxide, being an alkylating agent, it is a highly reactive sporicidal gas. It can rapidly penetrate and kill the endospores of microorganisms. Ethylene oxide is otherwise named oxirane. It is widely used in hospitals for sterilizing medical equipment, and heat sensitive tools. Therefore, the option (b) is correct.
Copper ions cannot penetrate any cell unless there are ion channels for their entry. Therefore, they can show no negative effect on endospores. Thus, option (a) is incorrect.
Ethylene can dissolve lipids, but not spore walls of the endospore. It cannot penetrate into the spore wall of endospore. Therefore, option (c) is incorrect.
Triclosan is a biocide, with number of membrane and cytoplasmic targets. It can act effectively on vegetative cells, but cannot act on spores. Therefore, the option (d) is also incorrect option.
Hence, the correct option is (b) ethylene oxide.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 17MC

Phenol is the disinfectant, which interferes with the cell membrane of microorganisms. They are active even in the presence of contaminating agents like pus and vomit. Therefore, the option (a) is correct.
Peracetic acid interferes with the metabolism of microorganisms, while silver nitrate and gluteraldehyde interferes with protein denaturation. Therefore, the options (b), (c), and (d) are incorrect options. Hence, the correct option is (a) phenol.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 18MC

Iodophor is iodine containing organic compound, which slowly releases iodine, a quat is a quaternary ammonium compound used for antimicrobial action and formalin is formaldehyde dissolved in water to make 37% solution. All these compounds do not contain alcohol in them. Therefore, the options (a), (b), and (c) are incorrect.
Tinctures are generally solutions of antimicrobial chemicals in alcohol. So, a tincture of bromine contains alcohol. This disinfectant is used in wide areas including space crafts for sterilizing different objects. Hence, the correct option is (d) a tincture of bromine.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 19MC

Ethylene oxide is used as an antimicrobial chemical to sterilize spacecraft. NASA (National Aeronautics and Space Administration) uses this gas to sterilize the spacecraft before landing on any new land. Therefore, the option (d) is correct.
Phenols are intermediate to low level disinfectants. They can disrupt cell membrane and denature proteins. They are more effective against aerobic microorganisms rather than anaerobic microorganisms. But they are not used in space crafts. Therefore, the option (a) is incorrect.
Alcohol has bactericidal, fungicidal, and virucidal properties. They are regarded as intermediate level disinfectants. They are very much effective against aerobic microorganisms, but not used in space crafts. Therefore, the option (b) is incorrect.
Heavy metals ions like zinc, silver, mercury, arsenic, and copper can as antimicrobial agents. They have the ability to combine with sulfur atoms present in cysteine molecule and thereby can disrupt the proteins. But, they are not used in space crafts. Thus, the option (c) is incorrect.
Hence, the correct option is (d) ethylene oxide.

Microbiology with Diseases by Taxonomy Chapter 9 Answers 20MC

Surfactants like quaternary ammonium compounds are mostly soluble in water. These are the synthetic detergents, which are more soluble in water than soaps. They are composed of ammonium cation (NH4⁺) in which the atoms of hydrogen are replaced by some other functional groups. For example, benzalkonium chloride, cetylpyridinium chloride etc. Since they are readily soluble in water, they are used in mouth washes. Thus, the option (a) is correct.
Though alcohols are soluble in water they are not readily soluble. Only simple and low carbon alcohols are soluble in water, but not the compounds that contain more number of carbon atoms. Therefore, the option (b) is incorrect.
Soaps have fatty acid ends and are less soluble in water compared to quaternary ammonium compounds. Therefore, the option (c) is incorrect.
Peracetic acid is more soluble in fats, rather than in water. It is a colorless, pungent, sour smelling liquid. It is included under the group hydroperoxides. Since, it is not water soluble the option (d) is incorrect. Hence, the correct option is (a) quaternary ammonium compounds.

Microbiology with Diseases by Taxonomy Chapter 9 Answers

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