Question 1

Tuberculosis is the disease cause by?

Accepted Answer

Answer reason: Tuberculosis (TB) is caused by the acid-fast bacillus Mycobacterium tuberculosis, most commonly affecting the lungs. Mycobacterium leprae causes leprosy (Hansen disease), not TB. Variola virus causes smallpox. Therefore, the correct causative organism for tuberculosis is Mycobacterium tuberculosis.

Question 2

The Mantoux test is used for?

Accepted Answer

Answer reason: The Mantoux test (tuberculin skin test/PPD) is used to detect prior sensitization to Mycobacterium tuberculosis by measuring delayed-type (type IV) hypersensitivity at the injection site. Induration (not redness) is measured after 48–72 hours to determine if the result is positive based on risk factors and size cutoffs. It helps identify latent TB infection and supports evaluation of possible TB exposure, but it does not by itself confirm active TB disease.

Question 3

An organism that causes disease is called?

Accepted Answer

Answer reason: A pathogen is a microorganism (or other agent) capable of causing disease in a host. A host is the organism that harbors the pathogen, while a vector transmits a pathogen between hosts (e.g., mosquito). “Infect” is a verb describing the process, not the name for the disease-causing organism.

Question 4

Which type of worm cause the iron deficiency anaemia ...?

Accepted Answer

Answer reason: Hookworms (e.g., Ancylostoma duodenale, Necator americanus) attach to the intestinal mucosa and feed on blood, causing chronic occult gastrointestinal blood loss. Over time this blood loss depletes iron stores and leads to iron deficiency anemia, often with microcytosis and hypochromia. Threadworms (Enterobius) mainly cause perianal itching, roundworms (Ascaris) cause malnutrition/obstruction, and tapeworms are more associated with vitamin B12 deficiency (Diphyllobothrium latum) than iron deficiency.

Question 5

Which one of the below is a water-borne disease?

Accepted Answer

Answer reason: Cholera is classically a water-borne infection caused by Vibrio cholerae and is transmitted via fecally contaminated water or food. It causes profuse watery diarrhea leading to dehydration and electrolyte loss. Chickenpox, measles, and mumps are primarily spread person-to-person through respiratory droplets/airborne routes rather than via contaminated water.

Question 6

Fungus that invade and cause rhinosinusitis or cause thrombosis?

Accepted Answer

Answer reason: Mucormycosis (zygomycosis), classically due to Rhizopus/Mucor species, is an angioinvasive fungal infection that commonly presents as rhinocerebral/rhinosinusitis disease in immunocompromised patients (especially uncontrolled diabetes with ketoacidosis). Its hallmark is invasion of blood vessels causing tissue ischemia, necrosis, and thrombosis. Histoplasmosis and blastomycosis more typically cause pulmonary/systemic disease rather than angioinvasive rhinosinusitis with thrombosis. Toxoplasmosis is a protozoal infection, not a fungus.

Question 7

Full form of RT-PCR is?

Accepted Answer

Answer reason: RT-PCR in common clinical diagnostic usage refers to real-time polymerase chain reaction, a nucleic acid amplification method that detects and quantifies DNA (or cDNA when starting from RNA) during the amplification cycles. The “real-time” component indicates fluorescence-based monitoring as the reaction proceeds, enabling quantification (e.g., Ct values). The other options are incorrect expansions and do not describe a recognized laboratory diagnostic technique.

Question 8

AIDS is caused by HIV. Which among the following is the genetic material of HIV?

Accepted Answer

Answer reason: HIV is a retrovirus (family Retroviridae, genus Lentivirus) that carries two copies of positive-sense single-stranded RNA as its genome. After entering the host cell, HIV uses reverse transcriptase to synthesize complementary DNA, which then integrates into the host genome. Therefore, the genetic material packaged in the virus particle is single-stranded RNA, not DNA or double-stranded RNA.

Question 9

Typhoid Fever is caused by?

Accepted Answer

Answer reason: Typhoid fever is caused by the bacterium Salmonella enterica serovar Typhi (Salmonella Typhi), transmitted via the fecal–oral route through contaminated food or water. Because it is a bacterial infection, it is treated with appropriate antibiotics and prevented with sanitation measures and vaccination in endemic/travel settings. Viral, fungal, and protozoal organisms do not cause typhoid fever.

Question 10

DOTS strategy is mainly used for?

Accepted Answer

Answer reason: DOTS (Directly Observed Treatment, Short-course) is a WHO-recommended public health strategy specifically designed to improve adherence to anti-tuberculosis therapy and reduce treatment failure and resistance. It includes supervised dosing, standardized regimens, reliable drug supply, and monitoring/reporting. Therefore, it is mainly used for TB control rather than HIV, malaria, or leprosy programs.

Question 11

Diphtheria affects the?

Accepted Answer

Answer reason: Respiratory diphtheria classically involves the upper respiratory tract, especially the pharynx/tonsils, producing sore throat and a thick gray pseudomembrane. This local throat infection can cause airway obstruction and cervical lymphadenopathy (“bull neck”). Although the toxin can cause systemic complications such as myocarditis and neuropathy, the primary site affected is the throat.

Question 12

Mushroom is a type of?

Accepted Answer

Answer reason: Mushrooms are the fruiting bodies of fungi and belong to the kingdom Fungi. Unlike plants, fungi do not contain chlorophyll and therefore do not photosynthesize. They are eukaryotic organisms that obtain nutrients by absorption from organic matter, distinguishing them from bacteria (prokaryotes) and algae (photosynthetic organisms).

Question 13

Which one of the below diseases is not spread by a mosquito?

Accepted Answer

Answer reason: Dengue, Zika, and chikungunya are arboviral infections transmitted primarily by Aedes mosquitoes. AIDS is caused by HIV, which is transmitted through sexual contact, blood exposure (e.g., needles, transfusion), and vertical transmission from parent to child. HIV does not replicate in mosquitoes and is not biologically transmitted by mosquito bites, so AIDS is not spread by mosquitoes.

Question 14

Which of the following microorganism is used in the production of yogurt?

Accepted Answer

Answer reason: Yogurt is produced by fermenting milk with lactic acid bacteria, classically including Lactobacillus species (e.g., L. delbrueckii subsp. bulgaricus). These organisms ferment lactose to lactic acid, lowering pH and causing milk proteins to coagulate, giving yogurt its texture and tang. While Streptococcus thermophilus is also commonly used, among the single options listed, Lactobacillus is the best answer. Staphylococcus and Mycobacterium are not used as starter cultures for yogurt production.

Question 15

Which microorganism causes tuberculosis?

Accepted Answer

Answer reason: Tuberculosis is caused by the bacterium Mycobacterium tuberculosis, an acid-fast bacillus transmitted primarily via airborne droplet nuclei. Viral, protozoal, and fungal pathogens can cause respiratory infections, but they do not cause classic tuberculosis. The bacterial cell wall (rich in mycolic acids) also explains TB’s acid-fast staining characteristics and need for prolonged multidrug therapy.

Question 16

One of the major components of the cell wall of most fungi is?

Accepted Answer

Answer reason: Most fungal cell walls contain chitin, a structural polysaccharide made of N-acetylglucosamine, which provides rigidity. Peptidoglycan is characteristic of bacterial cell walls, not fungi. Cellulose and hemicellulose are primarily plant cell wall components, making them less appropriate for most fungi.

Question 17

Name the parasite that causes malaria?

Accepted Answer

Answer reason: Malaria is caused by protozoan parasites of the genus Plasmodium (e.g., P. falciparum, P. vivax), transmitted to humans by the bite of infected female Anopheles mosquitoes. The other options are helminths (nematodes) and are associated with different diseases such as filariasis or capillariasis, not malaria. Therefore, Plasmodium is the single best answer.

Question 18

What is the mode of transmission of diphtheria?

Accepted Answer

Answer reason: Diphtheria (Corynebacterium diphtheriae) is primarily spread person-to-person via respiratory droplets from coughing or sneezing. Transmission can also occur from contact with contaminated secretions from skin lesions, but among the listed options droplet spread is the correct mode. It is not classically transmitted by fecal-oral route, sexual contact, or vectors. Therefore, droplet infection is the single best answer.

Question 19

Bacteria were discovered by?

Accepted Answer

Answer reason: Anton van Leeuwenhoek is credited with the first observations of bacteria and other microorganisms using his handcrafted microscopes in the 1670s, describing them as “animalcules.” Robert Hooke is best known for describing cells in cork and observing molds, not first discovering bacteria. Louis Pasteur established germ theory and developed pasteurization, while Edward Jenner pioneered vaccination against smallpox.

Question 20

Which of the following is not a viral disease?

Accepted Answer

Answer reason: Tetanus is not viral; it is caused by the bacterium Clostridium tetani, which produces a neurotoxin (tetanospasmin) leading to muscle rigidity and spasms. In contrast, rabies is caused by the rabies virus, influenza by influenza viruses, and herpes by herpes simplex viruses. Therefore, tetanus is the only option that is not a viral disease.

Question 21

Which of the following is an example of a communicable disease?

Accepted Answer

Answer reason: Tuberculosis is caused by Mycobacterium tuberculosis and is transmitted from person to person via airborne droplet nuclei, making it a communicable (infectious) disease. Diabetes, cancer, and hypertension are noncommunicable conditions that do not spread through infectious transmission. Therefore, tuberculosis is the only option that fits the definition of communicable disease.

Question 22

A sexually active 18-years old presents with postcoital spotting, dysuria and a yellow discharge. On exam you find her cervix is erythematous and bleeds with contact. The m/c likely diagnosis is?

Accepted Answer

Answer reason: A friable, erythematous cervix that bleeds on contact with mucopurulent/yellow discharge in a sexually active adolescent is classic for cervicitis, most commonly caused by Chlamydia trachomatis. Dysuria can occur from associated urethritis. Cervical cancer is unlikely at age 18 and does not typically present as acute mucopurulent cervicitis. Primary syphilis usually presents with a painless chancre rather than cervical friability with discharge, and tampon injury would not explain infectious-appearing discharge.

Question 23

Hepatitis B can be prevented by –?

Accepted Answer

Answer reason: Hepatitis B prevention is achieved through active immunization with the hepatitis B (HBV) vaccine, which induces protective anti-HBs antibodies. BCG protects primarily against tuberculosis, and DPT protects against diphtheria, pertussis, and tetanus. There is no licensed HIV vaccine for routine prevention, so it cannot be the correct option.

Question 24

Which one is a vector borne disease-?

Accepted Answer

Answer reason: Malaria is transmitted by a vector—female Anopheles mosquitoes—which carry Plasmodium parasites between humans. This is the defining feature of a vector-borne disease: the pathogen is spread via an intermediate arthropod. Poliomyelitis and typhoid are typically transmitted via the fecal–oral route (contaminated food/water). Tetanus results from wound contamination with Clostridium tetani spores and is not vector-borne.

Question 25

Common causative organism of urinary tract infection is –?

Accepted Answer

Answer reason: Escherichia coli is the most common cause of uncomplicated urinary tract infections, typically originating from the gastrointestinal flora and ascending via the urethra. It has virulence factors such as fimbriae that promote adherence to uroepithelium, facilitating colonization. Pseudomonas is more associated with complicated or catheter-associated UTIs, while mycobacterial and Salmonella UTIs are uncommon and usually occur in specific systemic disease contexts.

Question 26

Major neonatal infection is –?

Accepted Answer

Answer reason: Umbilical sepsis (omphalitis) is a major neonatal infection because the umbilical stump provides a direct portal of entry for bacteria in the early neonatal period. It can rapidly progress to systemic infection and sepsis if not recognized and treated promptly. Thrush is typically a localized mucocutaneous Candida infection, and jaundice is usually a sign/condition rather than an infection. Pneumonia can occur in neonates, but “umbilical sepsis” is classically emphasized as a major neonatal infection related to cord care and high risk of systemic spread.

Question 27

Dengue fever can be prevented by controlling ______?

Accepted Answer

Answer reason: Dengue fever is transmitted primarily by Aedes mosquitoes (especially Aedes aegypti), so prevention focuses on vector control and avoiding mosquito bites. Measures include eliminating standing water, using insecticide-treated measures, repellents, and protective clothing. House flies, rodents, and bed bugs are not vectors for dengue transmission.

Question 28

The absence of bacteria, viruses and other microorganisms is called —?

Accepted Answer

Answer reason: Asepsis refers to the absence of pathogenic microorganisms and the state of being free from contamination by bacteria, viruses, and other microbes. Antisepsis is the use of chemicals on living tissue to inhibit or destroy microorganisms, not the condition itself. Disinfection reduces microbial load on inanimate objects but does not necessarily eliminate all microorganisms (especially spores). Therefore, the term describing the absence of microorganisms is asepsis.

Question 29

Which one is not studied in microbiology?

Accepted Answer

Answer reason: Microbiology focuses on microscopic organisms such as bacteria and fungi, and often includes microscopic algae (e.g., certain unicellular forms). Animal behavior is studied in zoology/ethology and behavioral science rather than microbiology. Therefore, among the options, animal behavior is the one not studied in microbiology.

Question 30

Which mosquitoes transmit malaria to humans?

Accepted Answer

Answer reason: Malaria is transmitted to humans by the bite of infected female Anopheles mosquitoes, which inject Plasmodium sporozoites during blood feeding. Only female mosquitoes blood-feed (males feed on nectar), so males do not transmit malaria. Female Aedes are vectors for diseases like dengue, Zika, and chikungunya rather than malaria. Therefore, the single best answer is Female Anopheles.

Question 31

Scabies is caused by?

Accepted Answer

Answer reason: Scabies is an ectoparasitic infestation caused by the mite Sarcoptes scabiei var. hominis, which burrows into the stratum corneum. This leads to intense pruritus and characteristic lesions due to hypersensitivity to the mite, eggs, and feces. It is therefore not caused by a virus, bacteria, or helminths (worms).

Question 32

Ringworm is caused by?

Accepted Answer

Answer reason: Ringworm (tinea) is a superficial dermatophyte infection caused by fungi such as Trichophyton, Microsporum, or Epidermophyton. Despite the name, no worms are involved; the lesions are typically annular with central clearing due to fungal growth patterns. It is not caused by bacteria or viruses, and treatment is primarily topical or systemic antifungals depending on severity and location.

Question 33

An organism that transmits diseases to another living organism is called?

Accepted Answer

Answer reason: A vector is a living organism (often an arthropod like a mosquito or tick) that carries and transmits an infectious agent from one host to another. A host is the organism that harbors the pathogen, not necessarily the transmitter. A pathogen is the disease-causing microorganism itself, while “infect” is a verb describing the process rather than a transmitting organism.

Question 34

Tuberculosis is caused by -?

Accepted Answer

Answer reason: Tuberculosis is caused by organisms in the Mycobacterium tuberculosis complex, which includes M. tuberculosis, M. bovis, and M. africanum. These species are capable of causing TB disease in humans (with M. bovis more often associated with zoonotic transmission). Therefore, the most inclusive and correct option is that all listed organisms can cause tuberculosis.

Question 35

Trachoma is caused by?

Accepted Answer

Answer reason: Trachoma is a chronic conjunctivitis caused by the bacterium Chlamydia trachomatis (classically serovars A, B, Ba, and C). Recurrent infection leads to conjunctival scarring, entropion, trichiasis, and corneal opacity. Because the etiologic agent is bacterial (an obligate intracellular organism), the correct choice is bacteria rather than virus, fungus, or helminth.

Question 36

Hepatitis B can be transmitted from mother to child at birth. This is called?

Accepted Answer

Answer reason: Mother-to-child transmission occurring during pregnancy, delivery, or shortly after birth is termed vertical transmission. Hepatitis B is a classic example because an infected mother can transmit HBV to the newborn during childbirth via exposure to blood and body fluids. Horizontal transmission refers to person-to-person spread within the same generation (e.g., sexual contact, needles), not parent-to-child at birth. Airborne and foodborne routes do not describe typical HBV transmission.

Question 37

A patient's laboratory report shows acid fast rods in his sputum. These rods are presumed to be?

Accepted Answer

Answer reason: Acid-fast rods in sputum are characteristic of organisms with mycolic-acid–rich cell walls that retain carbol fuchsin stain after acid-alcohol decolorization. Mycobacterium tuberculosis is the classic acid-fast bacillus associated with pulmonary infection and is detected on sputum AFB smear. Bordetella pertussis and Corynebacterium diphtheriae are not acid-fast, and influenza is a virus (not a rod-shaped bacterium). Therefore, the most likely organism is Mycobacterium tuberculosis.

Question 38

Which genus of bacteria causes tuberculosis and leprosy?

Accepted Answer

Answer reason: Tuberculosis is caused by Mycobacterium tuberculosis and leprosy is caused by Mycobacterium leprae, both members of the genus Mycobacterium. These organisms are characteristically acid-fast due to mycolic acids in their cell walls, which is a key microbiology feature of this genus. The other listed genera do not include the classic causative agents of TB or leprosy.

Question 39

A patient presents with complaints of watery diarrhea and pain abdomen. He has drug history of Clindamycin intake for a pre-existing infection. The most likely organism responsible for this condition is?

Accepted Answer

Answer reason: Recent clindamycin use is a classic risk factor for antibiotic-associated diarrhea due to disruption of normal colonic flora, allowing overgrowth of toxigenic Clostridioides (Clostridium) difficile. C. difficile produces toxins A and B that cause colitis, classically presenting with watery diarrhea and abdominal pain. The other listed organisms are not the typical cause of post-antibiotic pseudomembranous colitis, making C. difficile the best answer.

Question 40

Which test is used for syphilis screening?

Accepted Answer

Answer reason: VDRL is a classic non-treponemal serologic test used for syphilis screening because it is inexpensive and can be quantified (titers) to help follow disease activity and response to treatment. It detects antibodies to cardiolipin (reagin), not specific treponemal antibodies, so false positives can occur and confirmatory treponemal testing is typically required. Western blot is not the standard screening test for syphilis (more associated with HIV confirmation), and PCR is not routinely used for population screening. ELISA may be used in some treponemal screening algorithms, but among the listed options VDRL is the standard screening answer.

Question 41

Hepatitis A is an acute viral disease of the liver that is essential transmitted through ...?

Accepted Answer

Answer reason: Hepatitis A virus is primarily transmitted via the fecal–oral route, usually through contaminated food or water or close person-to-person contact. Unlike hepatitis B and C, HAV is not typically spread through blood exposure. Droplet and skin transmission are not the main modes for HAV infection. Therefore, the best answer is fecal-oral transmission.

Question 42

What is the treatment of choice for diphtheria?

Accepted Answer

Answer reason: Diphtheria management requires immediate diphtheria antitoxin to neutralize circulating toxin and prevent progression of systemic complications such as myocarditis and neuropathy. Antibiotics (classically erythromycin or penicillin) are given to eradicate Corynebacterium diphtheriae and stop further toxin production and transmission. Antibiotics alone do not inactivate toxin already produced, so antitoxin plus antibiotics is the treatment of choice. Supportive care (e.g., airway management, fluids) may be needed but is not definitive therapy.

Question 43

AIDS stands for?

Accepted Answer

Answer reason: AIDS is the established acronym for Acquired Immune Deficiency Syndrome, the advanced clinical stage of HIV infection characterized by severe immunosuppression. It is termed “acquired” because it is not inherited; it results from infection with HIV. The immune deficiency reflects progressive CD4+ T-cell depletion leading to opportunistic infections and certain malignancies.

Question 44

What is the incubation period of measles?

Accepted Answer

Answer reason: Measles (rubeola) typically has an incubation of about 10–12 days from exposure to the onset of prodromal symptoms (fever, cough, coryza, conjunctivitis). The rash usually appears later, around ~14 days after exposure, which can make longer ranges tempting but refers to rash onset rather than initial symptoms. Therefore, 10–12 days is the best match for the incubation period as commonly tested.

Question 45

Which of the following is the tiny blob-on-a-stick structures in fungi that are involved in reproduction?

Accepted Answer

Answer reason: In many fungi, the "blob-on-a-stick" appearance describes a sporangium sitting atop a sporangiophore (a stalk), forming a sporangium-bearing structure used in asexual reproduction. The sporangium is the sac-like structure that produces and contains spores, which are then dispersed to propagate the fungus. The other options (spermatogonia, sporophyte, gametophyte) refer to animal reproductive cells or plant life-cycle stages rather than typical fungal spore sacs.

Question 46

What is the causative agent of AIDS?

Accepted Answer

Answer reason: AIDS is caused by infection with Human Immunodeficiency Virus (HIV), a retrovirus that targets CD4+ T lymphocytes and leads to progressive immunodeficiency. The other listed viruses can cause important illnesses (e.g., hepatitis B causes hepatitis; HSV causes herpes; EBV causes infectious mononucleosis and is linked to certain cancers) but they do not cause AIDS. Therefore, HIV is the causative agent of AIDS.

Question 47

A nurse if reviewing a patient’s chart and notices that the patient suffers from conjunctivitis. Which of the following microorganisms is related to this condition?

Accepted Answer

Answer reason: Conjunctivitis can be caused by several bacteria, including Haemophilus species; Haemophilus aegyptius (Koch-Weeks bacillus) is classically associated with acute bacterial conjunctivitis. The other options are linked to different diseases: Yersinia pestis causes plague, Helicobacter pylori causes gastritis/peptic ulcer disease, and Vibrio cholerae causes cholera. Therefore, Hemophilus aegyptius is the best match for conjunctivitis among the choices.

Question 48

Which of the following is a fungal infection?

Accepted Answer

Answer reason: Candidiasis is caused by Candida species (most commonly Candida albicans), which are fungi/yeasts, making it a fungal infection. Tuberculosis is caused by Mycobacterium tuberculosis (a bacterium). Typhoid is caused by Salmonella Typhi (a bacterium), and tetanus is caused by Clostridium tetani (a bacterium) producing a neurotoxin.

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