Question 1

Which of the following is NOT a sexually transmitted disease (STD)?

Accepted Answer

Answer reason: Hepatitis A is not a sexually transmitted disease. It spreads primarily through the fecal–oral route, usually via contaminated food or water. In contrast, AIDS (HIV), syphilis, and gonorrhea are true sexually transmitted infections.

Question 2

What term best describes the widespread global outbreak of COVID-19?

Accepted Answer

Answer reason: A pandemic refers to an outbreak of an infectious disease that spreads across multiple countries or continents, affecting a large proportion of the global population. COVID-19 met this definition due to its rapid worldwide transmission.

Question 3

Which of the following bacteria is not a source of restriction endnuclease?

Accepted Answer

Answer reason: Classical restriction endonucleases are sourced from bacteria such as Haemophilus influenzae (Hind), Escherichia coli (EcoRI), and Bacillus amyloliquefaciens (BamHI). Agrobacterium tumefaciens is primarily used as a gene-transfer vector, not as a standard source of restriction enzymes.

Question 4

Area of the cytoplasm that contains the single bacterial DNA molecule?

Accepted Answer

Answer reason: In prokaryotes, the single circular chromosome is located in the nucleoid region of the cytoplasm.

Question 5

Streptomycin is produced by?

Accepted Answer

Answer reason: Streptomycin was originally isolated from the actinomycete Streptomyces griseus; the other listed species produce different antibiotics.

Question 6

Which hepatitis has the maximum mortality in pregnancy?

Accepted Answer

Answer reason: Hepatitis E virus is associated with the highest maternal mortality, particularly in the third trimester, due to the risk of fulminant hepatic failure.

Question 7

Which of the following diseases is transmitted by ticks?

Accepted Answer

Answer reason: Lyme disease is transmitted by Ixodes ticks. Malaria and dengue are mosquito-borne, and typhoid fever is spread via contaminated food or water.

Question 8

Which parasitic infestation can cause anemia?

Accepted Answer

Answer reason: Hookworms attach to the intestinal mucosa and feed on blood, causing chronic blood loss and iron-deficiency anemia.

Question 9

The causative organism for roundworm infestation is?

Accepted Answer

Answer reason: Human roundworm infection (ascariasis) is caused by the nematode Ascaris lumbricoides. The other options are unrelated organisms: Neisseria is a bacterium, Pediculus is a louse, and the liver fluke is a trematode, not a roundworm.

Question 10

Which of the following causes endocarditis in patients with underlying colorectal carcinoma?

Accepted Answer

Answer reason: Streptococcus bovis (S. gallolyticus) bacteremia or endocarditis is classically associated with colorectal malignancy; its detection should prompt evaluation for colon cancer.

Question 11

What is poliomyelitis otherwise known as?

Accepted Answer

Answer reason: Poliomyelitis, a viral infection affecting motor neurons, has historically been called infantile paralysis. Zika fever and blackwater fever are distinct diseases.

Question 12

In which of the following do lactic acid bacteria grow?

Accepted Answer

Answer reason: Lactic acid bacteria, such as Lactobacillus, proliferate in curd (yogurt), where they ferment lactose to lactic acid; water or juice are not their typical growth environments.

Question 13

What is the term for bacteria that have a single flagellum at each end?

Accepted Answer

Answer reason: Amphitrichous bacteria have a single flagellum at each pole. Monotrichous bacteria have one at one pole, lophotrichous bacteria have a tuft at one pole, and peritrichous bacteria have flagella distributed all around.

Question 14

Media used for the production of chlortetracycline consist of?

Accepted Answer

Answer reason: Chlortetracycline fermentation requires a carbon source (sugar), complex nutrients from corn steep liquor, buffering with CaCO3, and ammonium salts as nitrogen sources; only option A contains all of these components.

Question 15

The prokaryotic genetic system has?

Accepted Answer

Answer reason: Prokaryotic cells contain DNA but lack histone proteins that package DNA in eukaryotes. Their genetic material is typically a single circular chromosome without histone association.

Question 16

What is the most common cause of diarrhea in children?

Accepted Answer

Answer reason: Rotavirus is the leading cause of acute gastroenteritis and severe diarrhea in young children worldwide; Adenovirus and Giardia are less common.

Question 17

Who described the tetanus bacillus?

Accepted Answer

Answer reason: Arthur Nicolaier first described the tetanus bacillus (later isolated by Kitasato).

Question 18

Which disease is caused by a dog bite?

Accepted Answer

Answer reason: Rabies is transmitted via the saliva of infected animals, commonly through dog bites; the other options are unrelated (vitamin C deficiency, a nonspecific term, and a genetic condition).

Question 19

A 16-year-old girl presents with fever (39°C), pelvic pain, generalized malaise, and nausea a few days after unprotected intercourse. What is the most likely diagnosis?

Accepted Answer

Answer reason: Primary HSV infection typically presents 2–12 days after exposure with systemic, flu-like symptoms such as fever, malaise, and nausea, along with pelvic or genital pain; other options do not match this acute timing and symptom pattern.

Question 20

Which of the following diseases are related to coronavirus?

Accepted Answer

Answer reason: MERS and SARS are both caused by coronaviruses (MERS-CoV and SARS-CoV), so both options A and B are correct.

Question 21

What is the causative agent of tetanus?

Accepted Answer

Answer reason: Tetanus is caused by Clostridium tetani, a spore-forming anaerobic bacterium that produces the tetanospasmin neurotoxin.

Question 22

The yield of the antibiotic depends upon?

Accepted Answer

Answer reason: Antibiotic production during fermentation is affected by culture pH, inoculum age, and medium composition; all influence yield.

Question 23

Penicillin is recovered after fermentation as?

Accepted Answer

Answer reason: In industrial recovery, penicillin from the fermentation broth is commonly converted to the stable, water-soluble potassium salt for extraction and crystallization.

Question 24

A high yield of chlorotetracycline requires?

Accepted Answer

Answer reason: Chlortetracycline is produced by aerobic fermentation; optimal oxygen levels must be maintained to maximize secondary metabolite production. Controlled aeration yields the highest output.

Question 25

A worm infestation transmitted through meat is?

Accepted Answer

Answer reason: Tapeworms (Taenia saginata/solium) are acquired by eating undercooked beef or pork containing cysticerci. Hookworm, pinworm, and Ascaris have other transmission routes.

Question 26

Pneumonia is most commonly caused by ____.?

Accepted Answer

Answer reason: Community-acquired pneumonia is most often caused by bacterial pathogens, classically Streptococcus pneumoniae; viruses, fungi, and chemical pneumonitis are less common overall.

Question 27

Measles is caused by?

Accepted Answer

Answer reason: Measles is caused by the rubeola (measles) virus, a Morbillivirus in the Paramyxoviridae family. Nipah and Hendra are Henipaviruses, and Pneumovirus refers to RSV, not to measles.

Question 28

On 11 February 2020, the World Health Organization announced an official name for the disease that is causing the 2019 novel coronavirus outbreak. What is the new name of the disease?

Accepted Answer

Answer reason: WHO officially named the disease caused by the 2019 novel coronavirus COVID-19 on Feb 11, 2020.

Question 29

The first case of the novel coronavirus was identified in...?

Accepted Answer

Answer reason: COVID-19 (SARS-CoV-2) was first identified in Wuhan, Hubei Province, China, in late 2019.

Question 30

What is the incubation period of scabies?

Accepted Answer

Answer reason: Primary scabies has an incubation period of about 2–6 weeks before symptoms appear; reinfestation presents sooner.

Question 31

Which of the following is true of Haemophilus influenzae?

Accepted Answer

Answer reason: Encapsulated H. influenzae, especially type b with a PRP capsule, causes invasive disease (e.g., meningitis, epiglottitis). Nonencapsulated strains cause mucosal infections. Other statements are false regarding epidemiology and culture requirements.

Question 32

The Widal test is a test for...?

Accepted Answer

Answer reason: The Widal test detects agglutinating antibodies (O and H) against Salmonella typhi and Salmonella paratyphi and is used to diagnose typhoid fever.

Question 33

HIV is a?

Accepted Answer

Answer reason: HIV is a retrovirus with a single-stranded RNA genome; it uses reverse transcriptase to make DNA during replication and is classified as an RNA virus.

Question 34

Culture media sterilized by?

Accepted Answer

Answer reason: The standard method to sterilize culture media is moist heat in an autoclave (121°C for ~15 min). Dry heat (hot-air oven) is used for glassware, and ethylene oxide or glutaraldehyde are used for heat-sensitive equipment, not media.

Question 35

Malaria is caused by?

Accepted Answer

Answer reason: Malaria is caused by Plasmodium species, which are protozoan parasites—not fungi or bacteria.

Question 36

Which of the following has "periodic fever (72 hours)" as its pathology?

Accepted Answer

Answer reason: Plasmodium malariae causes quartan malaria with fever spikes every 72 hours; P. vivax and P. ovale are tertian (48 hours), and P. falciparum is often irregular.

Question 37

Tuberculosis is the disease caused by ___?

Accepted Answer

Answer reason: Tuberculosis is caused by Mycobacterium tuberculosis; Mycobacterium leprae causes leprosy, and the variola virus causes smallpox.

Question 38

The world's smallest organism is?

Accepted Answer

Answer reason: Mycoplasmas are the smallest free-living organisms (cells); viruses are acellular and often not classified as organisms. Hence, option C.

Question 39

Trichomoniasis is caused by?

Accepted Answer

Answer reason: Trichomoniasis is caused by Trichomonas vaginalis, a protozoan parasite, not a fungus, bacterium, or virus.

Question 40

Whooping cough is an infection?

Accepted Answer

Answer reason: Whooping cough (pertussis) is caused by the bacterium Bordetella pertussis; therefore, it is a bacterial infection.

Question 41

Media of transmission of the bovine type of the tuberculosis bacillus?

Accepted Answer

Answer reason: Bovine tuberculosis (Mycobacterium bovis) is commonly transmitted to humans through the ingestion of unpasteurized milk and dairy products from infected cattle.

Question 42

Which disease does a dog bite cause?

Accepted Answer

Answer reason: Dog bites can transmit the rabies virus, causing rabies. Ringworm is a fungal skin infection, and cancer or a heart attack is not caused by dog bites.

Question 43

Which hepatitis virus is associated with the highest mortality in pregnancy?

Accepted Answer

Answer reason: Hepatitis E infection has the highest maternal mortality, especially in the third trimester, due to fulminant hepatic failure.

Question 44

From where did coronavirus get its name?

Accepted Answer

Answer reason: Coronaviruses are named for their characteristic halo or crown-like spikes on the viral envelope visible under electron microscopy (“corona” means crown in Latin).

Question 45

A Scotch tape swab is used to identify?

Accepted Answer

Answer reason: The Scotch tape swab (perianal cellulose tape test) detects Enterobius vermicularis eggs around the anus, diagnosing pinworm infection.

Question 46

Koplik's spot is a typical sign of which disease?

Accepted Answer

Answer reason: Koplik spots—tiny bluish-white lesions on the buccal mucosa—are pathognomonic for measles (rubeola).

Question 47

Which of the following is not a sexually transmitted disease?

Accepted Answer

Answer reason: Anthrax (Bacillus anthracis) is not transmitted sexually, whereas syphilis, gonorrhea, and HIV/AIDS are sexually transmitted infections.

Question 48

Which of the following has "stool examination" as its diagnosis?

Accepted Answer

Answer reason: Cryptosporidium parvum is an intestinal protozoan identified by oocysts in stool (acid-fast stain or antigen tests). Plasmodium spp. and Babesia are blood parasites diagnosed with blood smears, not stool.

Question 49

The percentage of formaldehyde in concentrated formalin?

Accepted Answer

Answer reason: Concentrated formalin is a commercial aqueous solution of formaldehyde containing about 37–40% formaldehyde by weight; commonly rounded to 40%.

Question 50

The Widal test is a test for ______?

Accepted Answer

Answer reason: The Widal test detects agglutinating antibodies (O and H) against Salmonella typhi/paratyphi, used to diagnose typhoid fever.

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

Microbiology NCLEX Practice Test

Continue Learning