Question 1

Which of the following statements is INCORRECT regarding prokaryotic cells?

Accepted Answer

Answer reason: All cells, including prokaryotes, must have a plasma (cell) membrane to maintain a controlled internal environment and regulate transport in and out of the cell. Prokaryotes characteristically lack a membrane-bound nucleus and other membrane-enclosed organelles, and their DNA is found in a nucleoid region rather than inside a nuclear membrane. They typically carry a single circular chromosome and replicate by binary fission, which are classic prokaryotic features. A common confusion is mixing up “cell wall” with “cell membrane”—some bacteria may lack a cell wall, but they still have a plasma membrane.

Question 2

What will happen if a bacterial cell is pretreated with a lysozyme solution, then placed in distilled water?

Accepted Answer

Answer reason: Lysozyme breaks the β(1→4) glycosidic bonds in peptidoglycan, weakening or removing the bacterial cell wall. In distilled water (a strongly hypotonic environment), water moves into the cell down its osmotic gradient. Without an intact wall to resist turgor pressure, the cytoplasmic membrane cannot withstand the influx and ruptures. Plasmolysis and water leaving the cell would occur in hypertonic conditions, not in distilled water.

Question 3

Normal microbiota provide protection from infection in each of the following ways EXCEPT?

Accepted Answer

Answer reason: Normal microbiota primarily protect the host via colonization resistance: occupying niches, competing for nutrients, and producing inhibitory substances that suppress pathogen growth. They can also modify the local environment (e.g., by generating acids or other metabolites) in ways that make it less favorable for nonresident organisms, including shifting local pH. Lysozyme, however, is a host-derived innate defense enzyme found in secretions such as tears, saliva, and mucus and produced by immune/epithelial cells rather than being a typical protective mechanism attributed to commensal flora. Therefore this choice is the exception compared with the established mechanisms of normal microbiota-mediated protection.

Question 4

Which of the following pairs is mismatched?

Accepted Answer

Answer reason: Puerperal (postpartum) sepsis is classically linked to Group A Streptococcus (Streptococcus pyogenes) as a historically important and highly virulent cause, so pairing it with a different organism makes this association incorrect in standard microbiology teaching. In contrast, acute bacterial endocarditis is strongly associated with Staphylococcus aureus, and subacute endocarditis is commonly due to viridans (alpha-hemolytic) streptococci. Burkitt’s lymphoma has a well-known association with Epstein–Barr virus, supporting that pairing as correct.

Question 5

Which of the following statements about puerperal sepsis is FALSE?

Accepted Answer

Answer reason: Puerperal sepsis refers to postpartum infection of the genital tract and surrounding tissues, typically arising from ascending bacterial contamination of the uterus after delivery or abortion. The process usually starts locally (endometritis or a wound infection) and may spread to cause systemic illness if untreated. Although cross-contamination from hands/instruments of health care personnel can contribute, the condition is primarily a maternal postpartum infection rather than a vertically transmitted infection to the fetus. The marked decline in incidence is explained by improved aseptic technique and effective antibiotic therapy.

Question 6

Which of the following pairs is mismatched?

Accepted Answer

Answer reason: Therefore labeling it as gram-positive (and as a pleomorphic bacillus) is the key mismatch. By contrast, Rickettsia are obligate intracellular organisms, and Bacillus are gram-positive spore-forming rods, which makes those pairings appropriate. Brucella are small gram-negative aerobic coccobacilli/rods, so that pairing is also acceptable at the level tested.

Question 7

Which of the following pairs is mismatched?

Accepted Answer

Answer reason: A malignant pustule is a hallmark lesion of cutaneous anthrax (Bacillus anthracis) that can progress to systemic disease if untreated, so pairing it with cat-scratch disease is incorrect. The other pairings match common clinical associations: brucellosis can cause undulating fever often worse in the evening, tularemia may present with an ulceroglandular lesion, Borrelia infection often presents with flu-like symptoms with rash, and congenital toxoplasmosis can cause significant CNS injury. Therefore this option is the mismatched pair.

Question 8

In humans, beef tapeworm infestations are acquired by ingesting?

Accepted Answer

Answer reason: Humans acquire the adult beef tapeworm by ingesting the larval cyst stage (cysticerci) in improperly cooked beef. After ingestion, the cysticercus evaginates in the small intestine, attaches to the mucosa, and matures into the adult tapeworm. In contrast, ingestion of Taenia eggs is more classically associated with larval disease (cysticercosis) and is particularly relevant to Taenia solium rather than typical beef tapeworm intestinal infection. The other listed exposures correspond to different parasites or the pork tapeworm lifecycle rather than beef-derived infection.

Question 9

Typhoid fever differs from salmonellosis in that in typhoid fever?

Accepted Answer

Answer reason: The key distinguishing principle is that typhoid fever (caused by Salmonella enterica serovar Typhi) is a systemic, invasive infection that survives and replicates intracellularly within macrophages, enabling dissemination via lymphatics and bloodstream. In contrast, typical non-typhoidal salmonellosis is primarily a localized gastroenteritis with inflammation largely confined to the intestinal mucosa. A longer incubation can occur with typhoid, but it is not as mechanistically defining and can overlap depending on inoculum and host factors. Gallbladder involvement is more related to chronic carriage and shedding rather than being the primary driver of acute symptom generation, and endospores are not part of Salmonella biology.

Question 10

Which of the following pertains to typhoid fever?

Accepted Answer

Answer reason: Typhoid fever is caused by Salmonella enterica serotype Typhi, a facultative intracellular pathogen that survives and replicates within macrophages after invading intestinal M cells. This intracellular replication enables dissemination through the reticuloendothelial system and subsequent bacteremia with systemic symptoms. A key differentiator is that typhoid is not primarily a toxin-mediated diarrheal illness; systemic spread is due to the organism, not enterotoxin traveling in blood. Bacillary dysentery instead refers to Shigella infection, and “several different species of Salmonella” describes non-typhoidal salmonellosis rather than typhoid fever.

Question 11

All of the following organisms are correctly matched to the recommended treatment EXCEPT?

Accepted Answer

Answer reason: Core principle: antimicrobial selection must match organism type (bacteria vs fungi vs viruses) and drug spectrum. Amphotericin B is a systemic antifungal that targets ergosterol in fungal cell membranes, a structure viruses do not possess. Poliovirus is an RNA virus, and management is primarily supportive with prevention via vaccination rather than antifungal therapy. In contrast, the other pairings align with standard treatments for bacterial meningitis pathogens (third-generation cephalosporins) and cryptococcal CNS infection (amphotericin B), and leprosy therapy includes dapsone-based regimens.

Question 12

Which of the following pairs is mismatched?

Accepted Answer

Answer reason: Cryptococcus neoformans is an encapsulated yeast (fungus) classically associated with meningitis in immunocompromised patients and does not have acid-fast staining characteristics. Acid-fast organisms are typically mycobacteria due to mycolic acids in their cell walls, and “rod” morphology points toward bacteria rather than yeast. The other pairs align with well-known virulence traits or disease associations in neuroinfections.

Question 13

All of the following are true of poliomyelitis EXCEPT?

Accepted Answer

Answer reason: Poliovirus infection is typically acquired via the fecal–oral route, with early replication in the oropharynx and intestinal mucosa before possible viremia. The great majority of infections are asymptomatic or cause only a mild, nonspecific illness, and only a small fraction progress to neurologic disease. Paralytic poliomyelitis occurs in a minority of cases, making the claim that most cases result in paralysis incorrect. A common misconception is to equate the feared complication with typical disease frequency, but epidemiologically paralysis is rare compared with inapparent infection.

Question 14

Bacterial encephalitis and meningitis are difficult to treat because?

Accepted Answer

Answer reason: The key principle is that the blood–brain barrier restricts entry of many drugs from the bloodstream into the central nervous system, limiting achievable antibiotic concentrations at the site of infection. Effective treatment requires agents with adequate CNS penetration (often enhanced during meningeal inflammation) and appropriate spectrum, otherwise bacterial pathogens persist despite therapy. This is why empiric regimens select specific high-penetration antibiotics and are adjusted once susceptibilities are known. A common distractor is the idea that antibiotics inherently harm nervous tissue; while some adverse effects exist, they are not the primary reason CNS bacterial infections are hard to treat.

Question 15

All of the following organisms are transmitted via the respiratory route EXCEPT?

Accepted Answer

Answer reason: The key principle is that “respiratory route” transmission typically involves droplets/aerosols from human nasopharyngeal carriage, whereas some CNS pathogens are acquired primarily through ingestion. This organism is classically foodborne (e.g., unpasteurized dairy, deli meats) with gastrointestinal entry followed by possible bacteremia and CNS invasion, not spread person-to-person via respiratory droplets. In contrast, both common bacterial meningitis pathogens listed (meningococcus and H. influenzae) are well-known to spread via respiratory droplets/secretions from the upper airway. Therefore the “all are respiratory” option is incorrect because one listed pathogen is predominantly acquired by the fecal-oral/foodborne route.

Question 16

Which of the following pairs is mismatched?

Accepted Answer

Answer reason: Therefore, pairing botulism with “stimulates transmission” is incorrect. In contrast, tetanus toxin is a potent neurotoxin that interferes with inhibitory neurotransmitter release, which aligns with its listed association. Poliovirus replication in the oropharynx and gastrointestinal tract and leprosy-related deformities are also consistent with established microbiology.

Question 17

Which one of the following causes a disease characterized by the catarrhal, paroxysmal, and convalescent stages?

Accepted Answer

Answer reason: The organism responsible is a small gram-negative coccobacillus that produces toxins (notably pertussis toxin) that drive the characteristic respiratory disease. Diphtheria instead presents with pharyngitis and a pseudomembrane, while tuberculosis is a chronic granulomatous infection without these distinct stages. RSV typically causes bronchiolitis/pneumonia in infants and does not follow the staged pattern described.

Question 18

All of the following are true of the common cold EXCEPT?

Accepted Answer

Answer reason: The common cold is a self-limited viral upper respiratory infection for which there is no curative therapy that reliably changes the course of illness. Supportive care (e.g., analgesics/antipyretics, hydration, decongestants where appropriate) may provide symptomatic relief but does not markedly shorten duration or severity in most cases. In contrast, the etiologies (rhinoviruses and some coronaviruses), spread through respiratory droplets/aerosols and direct contact, and a typical duration around a week are well-established features. Complications such as otitis media or laryngitis can occur, especially in children or those with underlying risk factors.

Question 19

Why is vaccination for rubella recommended?

Accepted Answer

Answer reason: Rubella is usually a mild viral illness in children and adults, but maternal infection—especially in the first trimester—can transmit transplacentally and cause congenital rubella syndrome. This syndrome is classically associated with major fetal anomalies such as sensorineural deafness, cataracts, and congenital heart disease, along with growth restriction and neurodevelopmental impairment. The vaccination program is therefore primarily justified by prevention of fetal morbidity from congenital infection rather than by high childhood mortality. Statements about eradication are incorrect because outbreaks can still occur where immunity gaps exist.

Question 20

A 17-year-old boy has pus-filled cysts on his face and upper back. Microscopic examination reveals gram-positive rods. This infection is caused by?

Accepted Answer

Answer reason: Gram-positive rods associated with pilosebaceous units are classic for acne due to Cutibacterium (formerly Propionibacterium) acnes, which contributes to inflammatory pustules and cysts on the face and back in adolescents. The organism thrives in anaerobic conditions within plugged follicles and triggers inflammation via lipase activity and immune activation. Staphylococcus aureus is a gram-positive coccus (often in clusters) and more typical of folliculitis/abscesses rather than acne comedones/cysts. Viral and protozoal options do not fit gram-stain morphology or the acne distribution described.

Question 21

A 35-year-old woman has a red, raised rash on the inside of her thighs. Gram-stained skin scrapings show large budding cells with pseudohyphae. The infection is caused by?

Accepted Answer

Answer reason: Large budding yeast cells with pseudohyphae on a Gram-stained scraping are classic for Candida species, reflecting a dimorphic yeast form seen in superficial candidiasis. The inner thigh is a common intertriginous site where moisture and friction promote overgrowth, producing an erythematous, raised rash. The viral options would not show budding cells or pseudohyphae on Gram stain, and typical bacterial pathogens would appear as cocci (clusters for staphylococci or chains for streptococci) rather than yeast forms. Therefore the described microscopic morphology most directly identifies Candida as the causative organism.

Question 22

Which of the following is NOT an antimicrobial feature of the urinary system?

Accepted Answer

Answer reason: Urine flow provides a constant flushing effect, and urine characteristics such as pH can inhibit or limit proliferation of many organisms. The ureterovesical junction functions as a physiologic anti-reflux mechanism that helps prevent retrograde movement of urine and pathogens toward the kidneys. In contrast, the female urethra is not used to transmit seminal fluid, and this statement is anatomically incorrect rather than a protective antimicrobial feature.

Question 23

A pelvic examination of a 23-year-old woman showed vesicles and ulcerated lesions on her labia. Cultures were negative for Neisseria and Chlamydia; the VDRL test was negative. Which treatment is appropriate?

Accepted Answer

Answer reason: Antiviral therapy reduces viral replication, shortens symptom duration, and decreases viral shedding when started early in an outbreak. Acyclovir is a first-line antiviral option for HSV genital infection. Metronidazole targets anaerobes and Trichomonas, miconazole treats Candida, and penicillin is used for syphilis, none of which match a vesicular-ulcerative HSV presentation.

Question 24

A pelvic examination of a 23-year-old woman showed vesicles and ulcerated lesions on her labia. Cultures were negative for Neisseria and Chlamydia; the VDRL test was negative. Which of the following is probable?

Accepted Answer

Answer reason: Negative cultures for Neisseria and Chlamydia make cervicitis/urethritis etiologies (e.g., gonorrhea or typical chlamydial infection) less likely, and these pathogens do not typically present with vesicles. A negative VDRL argues against syphilis, which more often presents initially as a painless chancre rather than grouped vesicles and shallow ulcers. Candidiasis primarily causes pruritus with thick discharge and erythema, not vesicular ulcerations.

Question 25

A 25-year-old male presented with fever, malaise, and a rash on his chest, arms, and feet. Diagnosis was based on serological testing. The patient then reported that he had an ulcer on his penis two months earlier. This disease can be treated with?

Accepted Answer

Answer reason: The key principle is recognizing the stage-based presentation of syphilis and matching it to first-line antimicrobial therapy. A painless genital ulcer weeks to months earlier suggests primary syphilis (chancre), and subsequent systemic symptoms with a diffuse rash involving extremities is classic for secondary syphilis; serology is commonly used for diagnosis. Penicillin (benzathine penicillin G for uncomplicated early disease) is the recommended treatment and prevents progression and transmission. Antivirals like acyclovir treat herpes, while metronidazole and miconazole target protozoal/bacterial vaginosis-type anaerobes and fungi, respectively, making them mismatched to this spirochetal infection. Surgical management is not a standard therapy for syphilis.

Question 26

Conjugation differs from reproduction because conjugation?

Accepted Answer

Answer reason: Conjugation is a form of horizontal gene transfer in bacteria, where genetic material (often a plasmid) moves from a donor to a recipient via direct contact (e.g., sex pilus). This process increases genetic diversity and can spread traits like antibiotic resistance without creating new daughter cells. In contrast, reproduction involves vertical transmission of DNA during cell division (binary fission) with genome replication and formation of new cells. Options about transcription (DNA to RNA) and reverse transcription (RNA to DNA) describe information flow processes, not bacterial conjugation.

Question 27

Which of the following is an advantage of the standard plate count?

Accepted Answer

Answer reason: This is an advantage over direct microscopic counts, which include dead cells and debris and can overestimate true living load. The method is not immediate because colonies require incubation time, so rapid turnaround is not its strength. It also does not “readily” resolve aggregates because clumps can form a single colony and underestimate the true cell number.

Question 28

Researchers are developing a ribozyme that cleaves the HIV genome. This pharmaceutical agent could be described as?

Accepted Answer

Answer reason: A ribozyme is defined by the principle that RNA can function as an enzyme, catalyzing specific biochemical reactions such as RNA cleavage and ligation. Because the HIV genome is RNA, an agent designed to cleave it fits the concept of catalytic RNA targeting RNA substrates. A hydrolase is a broad protein-enzyme class and does not specifically describe the unique catalytic role of RNA itself. Protease inhibitors and reverse transcriptase inhibitors act on viral proteins rather than directly catalyzing cleavage of the viral RNA genome.

Question 29

Which of the following statements about anaerobic respiration is FALSE?

Accepted Answer

Answer reason: Anaerobic respiration uses an electron transport chain with a terminal electron acceptor other than oxygen, typically an inorganic molecule such as nitrate or sulfate. Using an organic molecule as the final electron acceptor describes fermentation, not anaerobic respiration, making this statement false for anaerobic respiration. Anaerobic respiration still produces ATP and generally yields less ATP than aerobic respiration because the alternative acceptors support less efficient oxidative phosphorylation. Many anaerobic respiratory chains still rely on cytochromes and related carriers to shuttle electrons through the membrane. Confusing fermentation with anaerobic respiration is a common distractor because both occur without oxygen but differ by presence of an ETC and type of terminal acceptor.

Question 30

Which of the following pairs is mismatched?

Accepted Answer

Answer reason: Cross-walls are a defining feature of septate hyphae, so pairing “coenocytic” with “with cross-walls” contradicts standard mycology morphology. The other pairs align with common definitions used to classify fungi by growth form and by clinical depth of infection (cutaneous vs systemic). This makes the hyphal description the clear mismatch.

Question 31

Which of the following statements regarding protozoa is FALSE?

Accepted Answer

Answer reason: Protozoa include many free-living species that are not pathogenic to humans, so it is incorrect to imply that almost all cause disease. Medically important protozoa represent a small subset compared with the wide diversity found in nature. In contrast, protozoa are indeed unicellular eukaryotes and commonly inhabit water and soil as part of normal ecosystems. Many protozoa reproduce asexually, and several important human pathogens (e.g., malaria, leishmaniasis) are transmitted by arthropod vectors, which makes those statements generally true.

Question 32

Which of the following statements is FALSE?

Accepted Answer

Answer reason: A core microbiology principle is that extreme resistance to heat and many chemicals is characteristic of bacterial endospores, not typical fungal reproductive spores. Fungal spores can aid survival and dispersal, but they generally do not demonstrate the same level of intrinsic resistance that makes endospores notoriously hard to eradicate. The other statements reflect common fungal biology: fungi can reproduce via sexual and asexual spores, and spore morphology is routinely used to identify fungi in the lab. A common distractor is confusing fungal spores with endospores; differentiating these spore types is key to selecting appropriate control measures and interpreting lab findings.

Question 33

The life cycle of the fish tapeworm is similar to that of the beef tapeworm. Which of the following is the most effective preventive measure?

Accepted Answer

Answer reason: Thorough cooking denatures parasite proteins and eliminates viable tapeworm larvae that could establish infection after ingestion. Refrigeration does not consistently kill larvae, and salting may be insufficient depending on concentration and duration. Gloves reduce contact exposure but do not prevent ingestion-related infection, and swimming avoidance is irrelevant because transmission is via eating contaminated/undercooked fish rather than water contact.

Question 34

You have isolated an aerobic gram-positive, endospore-forming bacterium that grows well on nutrient agar. To which of the following groups does it most likely belong?

Accepted Answer

Answer reason: Growth on nutrient agar is consistent with many Bacillus species as common, nonfastidious aerobes. In contrast, Gamma- and Deltaproteobacteria are Gram-negative Proteobacteria and would not match the Gram-positive endospore-forming description. Phototrophic bacteria are defined by energy acquisition (light) rather than this specific Gram/endospore phenotype, making it a poorer fit than Bacillales.

Question 35

Burkholderia was reclassified from the gammaproteobacteria to the betaproteobacteria because?

Accepted Answer

Answer reason: Modern bacterial taxonomy and reclassification are primarily driven by molecular phylogeny, especially comparisons of conserved rRNA gene sequences. A close rRNA sequence relationship indicates a shared evolutionary lineage, which can warrant moving an organism into a different proteobacterial class. Phenotypic traits like being a gram-negative rod or clinical syndromes it causes may help identification but do not determine higher-level phylogenetic placement. Likewise, survival in disinfectants is an environmental/virulence-associated characteristic and is not a criterion for class-level reclassification.

Question 36

Which of the following pairs is mismatched?

Accepted Answer

Answer reason: Atmospheric nitrogen fixation is performed by specific diazotrophs (e.g., certain free-living or symbiotic bacteria) that possess nitrogenase, and many are not classic chemoautotrophs. By contrast, sulfate-reducing bacteria characteristically generate hydrogen sulfide during anaerobic respiration, and actinomycetes can propagate via fragmentation of filamentous forms. The mismatch is therefore the attribution of atmospheric nitrogen fixation as a defining feature of chemoautotrophic bacteria.

Question 37

All of the following are true of M. leprae EXCEPT?

Accepted Answer

Answer reason: M. leprae is a very slow-growing mycobacterium with a long doubling time (classically on the order of days to weeks), which explains its prolonged incubation period and chronic clinical course. A 12-hour generation time would be inconsistent with its known biology and the slow progression of leprosy. The organism prefers cooler temperatures than core body temperature, contributing to involvement of cooler body regions. It also survives within macrophages and has tropism for Schwann cells in peripheral nerves, and it can be propagated in armadillos for research purposes.

Question 38

The female client has been diagnosed with genital warts. Which assessment findings should the nurse associate with genital warts?

Accepted Answer

Answer reason: They are often painless, so a key finding is visible lesions rather than significant tenderness. Painful vesicles are more typical of genital herpes, and a painless chancre is classic for primary syphilis rather than HPV. Therefore the finding of painless, cauliflower-appearing lesions best matches genital warts.

Question 39

The mother of an infant gives a history of poor feeding for a few days. A complete physical examination shows white plaques in the mouth with an erythematous base. The plaques stick to the mucous membranes tightly and bleed when scraped. The nurse would suspect which condition?

Accepted Answer

Answer reason: This can lead to painful feeding and poor intake in infants due to oral discomfort. In contrast, herpes typically presents with painful vesicles/ulcers, and measles is characterized by Koplik spots plus systemic febrile illness and rash rather than thick removable plaques. Chickenpox is primarily a generalized vesicular skin eruption, not isolated bleeding oral plaques.

Question 40

A baker forgets to put yeast in his bread dough. Which of the following do you expect to happen to the bread as a result?

Accepted Answer

Answer reason: Leavening in standard bread depends on yeast fermenting sugars and producing carbon dioxide gas. That CO2 gets trapped in the gluten network, creating bubbles that expand the dough and produce the characteristic rise and crumb structure. Without yeast, there is minimal CO2 generation, so the dough remains dense and flat even if baked normally. A sour taste is more consistent with lactic acid bacteria fermentation (e.g., sourdough), not simply omission of yeast, and baking time is not the primary predictable change.

Question 41

All of the following are advantages of a bioreactor instead of a flask culture EXCEPT?

Accepted Answer

Answer reason: Bioreactors are designed for controlled, scalable microbial growth by providing engineered control of physical and chemical parameters. Compared with flasks, they allow larger working volumes while maintaining better process control through sensors and automated regulation of pH, dissolved oxygen, temperature, and agitation. Mechanical stirring and sparging support more uniform aeration and mixing, improving mass transfer and culture consistency. Dedicated ports and closed-system design enable aseptic sampling, reducing contamination risk relative to repeatedly opening a flask.

Question 42

Commercial sterilization of processed canned foods uses a 12D treatment which is based upon a theoretical population of 1012 C. botulinum endospores in a can of food. After treatment, there would theoretically be how many endospores left?

Accepted Answer

Answer reason: Starting from 10^12 endospores, reducing by 12 logs yields 10^(12-12) = 10^0, which equals 1 remaining survivor on a theoretical basis. This is the basis of the “botulinum cook” standard for low-acid canned foods to achieve an extremely low probability of viable C. botulinum spores. Options like 10 or 100 correspond to only 11D or 10D reductions, respectively, and therefore do not match the definition of a 12D process.

Question 43

Which of the following is the best evidence for a three-domain system?

Accepted Answer

Answer reason: The three-domain system (Bacteria, Archaea, Eukarya) is primarily supported by molecular phylogeny using conserved genes that change slowly over evolutionary time. rRNA (especially small-subunit rRNA) is present in all cellular life and provides a reliable basis for comparing deep evolutionary relationships. Distinct rRNA sequence differences demonstrate that Archaea are as different from Bacteria as they are from Eukarya, supporting three fundamental lineages. By contrast, Gram reaction only classifies many bacteria, and traits like “extreme environments” are ecological and do not define domain-level phylogeny.

Question 44

Which of the following statements about gram-negative cell walls is FALSE?

Accepted Answer

Answer reason: Gram-negative bacteria are relatively less susceptible to penicillin because their outer membrane acts as a permeability barrier and they often possess periplasmic beta-lactamases that inactivate beta-lactam antibiotics. The thin peptidoglycan layer still helps prevent osmotic lysis in hypotonic environments, so that statement is true. The presence of an outer membrane containing lipopolysaccharide (endotoxin) supports the statements about an extra outer layer and potential toxicity in humans. The Gram stain characteristics of gram-negative organisms are tied to their cell envelope structure, including the outer membrane and thin peptidoglycan, rather than implying high penicillin sensitivity.

Question 45

Which of the following statements about schistosomiasis is FALSE?

Accepted Answer

Answer reason: Schistosomiasis is a helminth infection caused by trematodes (blood flukes), not nematodes. Cercariae from freshwater snails penetrate intact human skin, and pathology is largely driven by host inflammatory/immune reactions to eggs deposited in tissues. The freshwater aquatic snail serves as the intermediate host in the lifecycle. A distinguishing feature of adult schistosomes is the male’s gynecophoral canal, which holds the female worm.

Question 46

A patient returning from an extended trip into Mexico has the following symptoms: a papule at the site of a previous bug bite and enlarged lymph nodes. Microscopic examination of the papule reveals nucleated cells in white blood cells. The patient most likely has?

Accepted Answer

Answer reason: Leishmania is transmitted by sandflies and classically causes a papule/ulcer at the bite site with regional lymphadenopathy. The organism exists as intracellular amastigotes within nucleated cells of the mononuclear phagocyte system (e.g., macrophages), matching the finding of nucleated organisms inside white blood cells from the lesion. Malaria instead shows parasites within anucleate red blood cells and typically presents with cyclic fevers rather than a localized bite papule. Anthrax causes a painless black eschar, and brucellosis and schistosomiasis do not characteristically produce intracellular organisms in lesion WBCs from a bug bite papule.

Question 47

All of the following pertain to pinworm infections EXCEPT?

Accepted Answer

Answer reason: Enterobius vermicularis is a helminth that spreads via ingestion (and sometimes inhalation) of embryonated eggs from contaminated hands, bedding, clothing, and other fomites. The classic diagnostic method is the perianal “tape test,” because eggs are laid around the anus, especially at night. Because reinfection and household spread are common, treating close contacts/household members is often recommended along with strict hygiene and laundering. Waterborne “cysts” are characteristic of certain protozoa (e.g., Giardia), not pinworm, making this statement the exception.

Question 48

All of the following are true regarding African trypanosomiasis EXCEPT?

Accepted Answer

Answer reason: African trypanosomiasis (sleeping sickness) is a vector-borne protozoal infection transmitted by the tsetse fly, and untreated infection can progress to CNS involvement and death. T. brucei gambiense is responsible for the majority of human African trypanosomiasis cases and typically causes a more chronic illness than T. brucei rhodesiense. The statement claiming all subspecies have multiple hosts is inaccurate because host range differs by subspecies, and some Trypanosoma brucei subspecies are primarily animal pathogens with different epidemiology and reservoirs. The other statements correctly reflect the disease’s common name, vector, typical fatality if untreated, and the predominance of gambiense in human disease.

Question 49

All of the following are associated with botulism outbreaks EXCEPT?

Accepted Answer

Answer reason: Botulism outbreaks are classically linked to specific toxin types and exposure sources, and epidemiology shows higher risk in certain communities with traditional fermented marine foods. C. botulinum spores have been found in honey, supporting the infant botulism association and the avoidance of honey in infants. Type E illness is strongly associated with aquatic environments and seafood, aligning with foodborne outbreaks in northern regions. The statement claiming the lowest rate in Alaskan natives contradicts well-known outbreak patterns, making it the exception.

Question 50

Which of the following statements about rabies is FALSE?

Accepted Answer

Answer reason: Most infections in the U.S. are the result of bites from infected dogs. In the U.S., human rabies cases are now most commonly linked to bats, while dog-associated rabies has been largely controlled through vaccination and public health measures. Therefore attributing most U.S. infections to infected dog bites is epidemiologically incorrect. The other statements align with core rabies facts: it is a Lyssavirus infection, hydrophobia is a classic manifestation, and direct fluorescent antibody (immunofluorescence) testing is a standard diagnostic method. Incubation is variable but often falls in the range of weeks to a few months, making the stated average plausible compared with the clearly wrong U.S. source attribution.

Train with a large NCLEX question bank and jump into a full exam-style simulator

Microbiology NCLEX Practice Test

Continue Learning

Which of the following statements is INCORRECT regarding prokaryotic cells?

What will happen if a bacterial cell is pretreated with a lysozyme solution, then placed in distilled water?

Normal microbiota provide protection from infection in each of the following ways EXCEPT?

Which of the following pairs is mismatched?

Which of the following statements about puerperal sepsis is FALSE?

Which of the following pairs is mismatched?

Which of the following pairs is mismatched?

In humans, beef tapeworm infestations are acquired by ingesting?

Typhoid fever differs from salmonellosis in that in typhoid fever?

Which of the following pertains to typhoid fever?

All of the following organisms are correctly matched to the recommended treatment EXCEPT?

Which of the following pairs is mismatched?

All of the following are true of poliomyelitis EXCEPT?

Bacterial encephalitis and meningitis are difficult to treat because?

All of the following organisms are transmitted via the respiratory route EXCEPT?

Which of the following pairs is mismatched?

Which one of the following causes a disease characterized by the catarrhal, paroxysmal, and convalescent stages?

All of the following are true of the common cold EXCEPT?

Why is vaccination for rubella recommended?

A 17-year-old boy has pus-filled cysts on his face and upper back. Microscopic examination reveals gram-positive rods. This infection is caused by?

A 35-year-old woman has a red, raised rash on the inside of her thighs. Gram-stained skin scrapings show large budding cells with pseudohyphae. The infection is caused by?

Which of the following is NOT an antimicrobial feature of the urinary system?

A pelvic examination of a 23-year-old woman showed vesicles and ulcerated lesions on her labia. Cultures were negative for Neisseria and Chlamydia; the VDRL test was negative. Which treatment is appropriate?

A pelvic examination of a 23-year-old woman showed vesicles and ulcerated lesions on her labia. Cultures were negative for Neisseria and Chlamydia; the VDRL test was negative. Which of the following is probable?

A 25-year-old male presented with fever, malaise, and a rash on his chest, arms, and feet. Diagnosis was based on serological testing. The patient then reported that he had an ulcer on his penis two months earlier. This disease can be treated with?

Conjugation differs from reproduction because conjugation?

Which of the following is an advantage of the standard plate count?

Researchers are developing a ribozyme that cleaves the HIV genome. This pharmaceutical agent could be described as?

Which of the following statements about anaerobic respiration is FALSE?

Which of the following pairs is mismatched?

Which of the following statements regarding protozoa is FALSE?

Which of the following statements is FALSE?

The life cycle of the fish tapeworm is similar to that of the beef tapeworm. Which of the following is the most effective preventive measure?

You have isolated an aerobic gram-positive, endospore-forming bacterium that grows well on nutrient agar. To which of the following groups does it most likely belong?

Burkholderia was reclassified from the gammaproteobacteria to the betaproteobacteria because?

Which of the following pairs is mismatched?

All of the following are true of M. leprae EXCEPT?

The female client has been diagnosed with genital warts. Which assessment findings should the nurse associate with genital warts?

The mother of an infant gives a history of poor feeding for a few days. A complete physical examination shows white plaques in the mouth with an erythematous base. The plaques stick to the mucous membranes tightly and bleed when scraped. The nurse would suspect which condition?

A baker forgets to put yeast in his bread dough. Which of the following do you expect to happen to the bread as a result?

All of the following are advantages of a bioreactor instead of a flask culture EXCEPT?

Commercial sterilization of processed canned foods uses a 12D treatment which is based upon a theoretical population of 1012 C. botulinum endospores in a can of food. After treatment, there would theoretically be how many endospores left?

Which of the following is the best evidence for a three-domain system?

Which of the following statements about gram-negative cell walls is FALSE?

Which of the following statements about schistosomiasis is FALSE?

A patient returning from an extended trip into Mexico has the following symptoms: a papule at the site of a previous bug bite and enlarged lymph nodes. Microscopic examination of the papule reveals nucleated cells in white blood cells. The patient most likely has?

All of the following pertain to pinworm infections EXCEPT?

All of the following are true regarding African trypanosomiasis EXCEPT?

All of the following are associated with botulism outbreaks EXCEPT?

Which of the following statements about rabies is FALSE?

Think you’re ready for the NCLEX?

Leave a Reply Cancel reply