1. The causative organism of tuberculosis (TB) is:
a) Salmonella typhi
b) Mycobacterium tuberculosis
c) Vibrio cholerae
d) Clostridium tetani
Answer: b) Mycobacterium tuberculosis
Explanation: TB is a bacterial infection mainly affecting lungs, caused by M. tuberculosis.
2. The BCG vaccine is used against:
a) Typhoid
b) Tuberculosis
c) Cholera
d) Diphtheria
Answer: b) Tuberculosis
Explanation: BCG (Bacille Calmette–Guérin) vaccine provides protection against TB.
3. The causative organism of typhoid fever is:
a) Vibrio cholerae
b) Mycobacterium tuberculosis
c) Salmonella typhi
d) Yersinia pestis
Answer: c) Salmonella typhi
Explanation: Typhoid spreads through contaminated food and water.
4. The Widal test is used for diagnosis of:
a) Tuberculosis
b) Typhoid
c) Malaria
d) Cholera
Answer: b) Typhoid
Explanation: Widal test detects antibodies against Salmonella typhi.
5. Cholera is caused by:
a) Vibrio cholerae
b) Salmonella
c) Streptococcus
d) Plasmodium
Answer: a) Vibrio cholerae
Explanation: Cholera is a waterborne bacterial infection causing severe diarrhea.
6. The causative organism of plague is:
a) Bacillus anthracis
b) Yersinia pestis
c) Clostridium botulinum
d) Treponema pallidum
Answer: b) Yersinia pestis
Explanation: Plague (black death) spreads through rat fleas.
7. The causative agent of diphtheria is:
a) Clostridium tetani
b) Corynebacterium diphtheriae
c) Bacillus anthracis
d) Treponema pallidum
Answer: b) Corynebacterium diphtheriae
Explanation: Diphtheria causes throat infection and breathing difficulties.
8. Which bacterial disease is transmitted by rats and fleas?
a) Plague
b) Cholera
c) Typhoid
d) Diphtheria
Answer: a) Plague
Explanation: Plague spreads through flea bites of infected rats.
9. The causative organism of tetanus is:
a) Clostridium tetani
b) Bacillus anthracis
c) Yersinia pestis
d) Streptococcus
Answer: a) Clostridium tetani
Explanation: Tetanus bacteria enter through wounds and produce a toxin affecting nerves.
10. Lockjaw is a symptom of:
a) Typhoid
b) Tetanus
c) Cholera
d) Anthrax
Answer: b) Tetanus
Explanation: Tetanus toxin causes muscle stiffness and lockjaw.
11. Anthrax is caused by:
a) Clostridium botulinum
b) Bacillus anthracis
c) Vibrio cholerae
d) Salmonella
Answer: b) Bacillus anthracis
Explanation: Anthrax affects skin, lungs, and intestines; used as bioweapon.
12. The vaccine DPT provides immunity against:
a) Diphtheria, Pertussis, Tetanus
b) Dengue, Polio, Typhoid
c) Dysentery, Pneumonia, Tuberculosis
d) Diphtheria, Polio, Tetanus
Answer: a) Diphtheria, Pertussis, Tetanus
Explanation: DPT is a triple vaccine for bacterial diseases.
13. Leprosy is caused by:
a) Clostridium tetani
b) Mycobacterium leprae
c) Treponema pallidum
d) Streptococcus
Answer: b) Mycobacterium leprae
Explanation: Leprosy (Hansen’s disease) is a chronic bacterial infection affecting skin and nerves.
14. Pneumonia can be caused by:
a) Streptococcus pneumoniae
b) Haemophilus influenzae
c) Both a and b
d) None
Answer: c) Both a and b
Explanation: Pneumonia may be caused by Streptococcus pneumoniae or Haemophilus influenzae.
15. Syphilis is caused by:
a) Neisseria gonorrhoeae
b) Treponema pallidum
c) Chlamydia trachomatis
d) Mycobacterium
Answer: b) Treponema pallidum
Explanation: Syphilis is a sexually transmitted bacterial infection.
16. Gonorrhea is caused by:
a) Treponema pallidum
b) Chlamydia
c) Neisseria gonorrhoeae
d) Mycobacterium
Answer: c) Neisseria gonorrhoeae
Explanation: Gonorrhea is an STD caused by N. gonorrhoeae.
17. Which bacterial disease spreads mainly through contaminated milk?
a) Cholera
b) Tuberculosis (bovine type)
c) Typhoid
d) Tetanus
Answer: b) Tuberculosis (bovine type)
Explanation: Mycobacterium bovis can spread through unpasteurized milk.
18. Who discovered the bacterium Mycobacterium tuberculosis?
a) Louis Pasteur
b) Robert Koch
c) Alexander Fleming
d) Edward Jenner
Answer: b) Robert Koch
Explanation: Robert Koch discovered M. tuberculosis in 1882.
19. Who discovered penicillin, the first antibiotic?
a) Robert Koch
b) Alexander Fleming
c) Louis Pasteur
d) Edward Jenner
Answer: b) Alexander Fleming
Explanation: In 1928, Fleming discovered penicillin from Penicillium notatum.
20. Lockjaw is caused due to a toxin affecting:
a) Respiratory system
b) Nervous system
c) Digestive system
d) Circulatory system
Answer: b) Nervous system
Explanation: Tetanus toxin affects nerves → muscle spasms.
21. A spore-forming bacterium that causes food poisoning is:
a) Clostridium botulinum
b) E. coli
c) Vibrio cholerae
d) Streptococcus
Answer: a) Clostridium botulinum
Explanation: Botulism results from ingestion of toxin produced in canned food.
22. Typhoid fever is commonly spread through:
a) Air
b) Contaminated food and water
c) Mosquito bites
d) Animal bites
Answer: b) Contaminated food and water
Explanation: Typhoid spreads via feco-oral route.
23. The “Black Death” in medieval Europe was due to:
a) Cholera
b) Tuberculosis
c) Plague
d) Leprosy
Answer: c) Plague
Explanation: Bubonic plague killed millions in Europe in 14th century.
24. Which bacterial disease spreads through wounds?
a) Tetanus
b) Tuberculosis
c) Cholera
d) Typhoid
Answer: a) Tetanus
Explanation: Tetanus spores enter body via wounds and cuts.
25. Who is known as the “Father of Germ Theory”?
a) Robert Koch
b) Louis Pasteur
c) Joseph Lister
d) Edward Jenner
Answer: b) Louis Pasteur
Explanation: Pasteur proposed that microorganisms cause diseases.
26. The causative organism of AIDS is:
a) Hepatitis virus
b) HIV (Human Immunodeficiency Virus)
c) Influenza virus
d) Rabies virus
Answer: b) HIV (Human Immunodeficiency Virus)
Explanation: HIV attacks helper T-cells, weakening immunity and causing AIDS.
27. Which cells are destroyed by HIV?
a) Red blood cells
b) Helper T lymphocytes (CD4 cells)
c) Platelets
d) B lymphocytes
Answer: b) Helper T lymphocytes (CD4 cells)
Explanation: HIV targets CD4+ T-cells, reducing immune defense.
28. Which test is commonly used for detection of HIV infection?
a) ELISA
b) Widal
c) Mantoux
d) Vidal
Answer: a) ELISA
Explanation: ELISA test detects antibodies against HIV.
29. Polio is caused by:
a) HIV
b) Polio virus
c) Adenovirus
d) Influenza virus
Answer: b) Polio virus
Explanation: Polio is caused by poliovirus (Picornavirus family).
30. Polio affects primarily:
a) Heart
b) Brain
c) Nervous system
d) Lungs
Answer: c) Nervous system
Explanation: Polio virus infects motor neurons, causing paralysis.
31. Which vaccine is used for polio prevention?
a) BCG
b) OPV (Oral Polio Vaccine)
c) DPT
d) MMR
Answer: b) OPV (Oral Polio Vaccine)
Explanation: OPV (Sabin vaccine) gives immunity against polio.
32. Rabies is transmitted by:
a) Mosquito bites
b) Infected dog/animal bites
c) Contaminated food
d) Air
Answer: b) Infected dog/animal bites
Explanation: Rabies virus spreads via bite of infected animals.
33. The causative agent of rabies is:
a) Paramyxovirus
b) Rhabdovirus
c) Retrovirus
d) Flavivirus
Answer: b) Rhabdovirus
Explanation: Rabies is caused by rabies virus (Rhabdoviridae family).
34. The vaccine for rabies was developed by:
a) Robert Koch
b) Louis Pasteur
c) Edward Jenner
d) Alexander Fleming
Answer: b) Louis Pasteur
Explanation: Pasteur developed the first rabies vaccine in 1885.
35. Hepatitis affects mainly:
a) Heart
b) Lungs
c) Liver
d) Kidneys
Answer: c) Liver
Explanation: Hepatitis = inflammation of the liver caused by Hepatitis viruses (A–E).
36. Which hepatitis virus is transmitted through contaminated food and water?
a) Hepatitis A & E
b) Hepatitis B & C
c) Hepatitis D
d) All types
Answer: a) Hepatitis A & E
Explanation: Hepatitis A/E spread feco-orally, while B/C spread via blood/sexual contact.
37. Which hepatitis virus can cause chronic infection and liver cancer?
a) Hepatitis A
b) Hepatitis B & C
c) Hepatitis E
d) Hepatitis D only
Answer: b) Hepatitis B & C
Explanation: Hepatitis B and C can cause chronic liver disease and cancer.
38. Which vaccine is available against hepatitis?
a) Only Hepatitis A
b) Hepatitis A and B
c) Hepatitis C
d) None
Answer: b) Hepatitis A and B
Explanation: Effective vaccines exist for Hepatitis A and B.
39. Smallpox is caused by:
a) Variola virus
b) Varicella virus
c) Adenovirus
d) Measles virus
Answer: a) Variola virus
Explanation: Smallpox, eradicated in 1980, was caused by variola virus.
40. The first disease eradicated by vaccination was:
a) Polio
b) Smallpox
c) Measles
d) Plague
Answer: b) Smallpox
Explanation: WHO declared smallpox eradicated in 1980.
41. The first vaccine developed by Edward Jenner was against:
a) Measles
b) Rabies
c) Smallpox
d) Polio
Answer: c) Smallpox
Explanation: Jenner developed smallpox vaccine in 1796 using cowpox virus.
42. Measles is caused by:
a) Variola virus
b) Paramyxovirus (Morbillivirus)
c) Adenovirus
d) Retrovirus
Answer: b) Paramyxovirus (Morbillivirus)
Explanation: Measles causes fever, rash, and can lead to pneumonia.
43. Chickenpox is caused by:
a) Variola virus
b) Varicella-zoster virus
c) Pox virus
d) Adenovirus
Answer: b) Varicella-zoster virus
Explanation: Chickenpox is caused by Varicella-zoster, a herpesvirus.
44. Which viral disease is also known as “German measles”?
a) Rubeola
b) Rubella
c) Chickenpox
d) Smallpox
Answer: b) Rubella
Explanation: Rubella (German measles) is caused by Rubella virus.
45. Influenza (flu) is caused by:
a) Orthomyxovirus
b) Adenovirus
c) Paramyxovirus
d) Retrovirus
Answer: a) Orthomyxovirus
Explanation: Influenza virus (Orthomyxoviridae) causes seasonal flu.
46. The causative agent of COVID-19 is:
a) SARS-CoV
b) SARS-CoV-2
c) MERS-CoV
d) H1N1 virus
Answer: b) SARS-CoV-2
Explanation: COVID-19 is caused by the novel coronavirus SARS-CoV-2.
47. Athlete’s foot is caused by:
a) Virus
b) Fungus
c) Bacterium
d) Protozoan
Answer: b) Fungus
Explanation: Athlete’s foot (Tinea pedis) is a fungal infection.
48. Ringworm is caused by:
a) Roundworms
b) Fungus (Dermatophytes)
c) Virus
d) Bacteria
Answer: b) Fungus (Dermatophytes)
Explanation: Ringworm is caused by fungi like Trichophyton, Microsporum.
49. Candidiasis (thrush) is caused by:
a) Aspergillus
b) Candida albicans
c) Penicillium
d) Rhizopus
Answer: b) Candida albicans
Explanation: Candida is a yeast causing oral and genital thrush.
50. Aspergillosis is caused by:
a) Candida
b) Trichophyton
c) Aspergillus
d) Microsporum
Answer: c) Aspergillus
Explanation: Aspergillus fungus infects lungs and sinuses, especially in immunocompromised persons.
51. Malaria is caused by:
a) Virus
b) Bacterium
c) Protozoan (Plasmodium)
d) Fungus
Answer: c) Protozoan (Plasmodium)
Explanation: Malaria is caused by Plasmodium species transmitted by female Anopheles mosquito.
52. Which species causes malignant (severe) malaria?
a) Plasmodium vivax
b) Plasmodium malariae
c) Plasmodium falciparum
d) Plasmodium ovale
Answer: c) Plasmodium falciparum
Explanation: P. falciparum causes cerebral malaria, most fatal type.
53. The infective stage of malaria parasite for humans is:
a) Gametocyte
b) Sporozoite
c) Merozoite
d) Trophozoite
Answer: b) Sporozoite
Explanation: Sporozoites from mosquito saliva infect humans.
54. The organ first affected in malaria is:
a) Brain
b) Liver
c) Heart
d) Kidney
Answer: b) Liver
Explanation: Sporozoites first multiply in liver before entering red blood cells.
55. The vector of malaria is:
a) Culex mosquito
b) Female Anopheles mosquito
c) Aedes mosquito
d) Sandfly
Answer: b) Female Anopheles mosquito
Explanation: Female Anopheles transmits malaria.
56. Kala-azar (black fever) is caused by:
a) Plasmodium
b) Leishmania donovani
c) Entamoeba histolytica
d) Giardia
Answer: b) Leishmania donovani
Explanation: Kala-azar is transmitted by sandfly.
57. The vector of kala-azar is:
a) Mosquito
b) Sandfly (Phlebotomus)
c) Housefly
d) Tsetse fly
Answer: b) Sandfly (Phlebotomus)
Explanation: Sandfly transmits Leishmania.
58. Sleeping sickness is caused by:
a) Entamoeba
b) Trypanosoma gambiense
c) Leishmania
d) Giardia
Answer: b) Trypanosoma gambiense
Explanation: Sleeping sickness is transmitted by tsetse fly.
59. The vector of sleeping sickness is:
a) Housefly
b) Tsetse fly
c) Sandfly
d) Aedes mosquito
Answer: b) Tsetse fly
Explanation: Tsetse fly transmits Trypanosoma.
60. Amoebic dysentery is caused by:
a) Giardia lamblia
b) Entamoeba histolytica
c) Trichomonas vaginalis
d) Ascaris lumbricoides
Answer: b) Entamoeba histolytica
Explanation: Amoebiasis spreads through contaminated food and water.
61. Giardiasis is caused by:
a) Giardia lamblia
b) Entamoeba
c) Trypanosoma
d) Leishmania
Answer: a) Giardia lamblia
Explanation: Giardia causes diarrhea and malabsorption.
62. Trichomoniasis is caused by:
a) Trichomonas vaginalis
b) Entamoeba
c) Plasmodium
d) Giardia
Answer: a) Trichomonas vaginalis
Explanation: It is a sexually transmitted protozoan infection.
63. Filariasis (elephantiasis) is caused by:
a) Wuchereria bancrofti
b) Ascaris lumbricoides
c) Taenia solium
d) Plasmodium
Answer: a) Wuchereria bancrofti
Explanation: Transmitted by Culex mosquito, causes swelling of legs/genitals.
64. The vector of filariasis is:
a) Anopheles mosquito
b) Aedes mosquito
c) Culex mosquito
d) Sandfly
Answer: c) Culex mosquito
Explanation: Culex mosquito spreads filarial worm.
65. Ascariasis is caused by:
a) Taenia
b) Ascaris lumbricoides
c) Trichinella
d) Ancylostoma
Answer: b) Ascaris lumbricoides
Explanation: Roundworm infection spreads via contaminated vegetables/water.
66. Hookworm disease is caused by:
a) Ancylostoma duodenale
b) Ascaris lumbricoides
c) Wuchereria
d) Taenia
Answer: a) Ancylostoma duodenale
Explanation: Hookworm enters through skin, causes anemia.
67. The infective stage of hookworm is:
a) Egg
b) Larva
c) Adult worm
d) Cyst
Answer: b) Larva
Explanation: Filariform larvae penetrate skin, enter bloodstream.
68. Taeniasis is caused by:
a) Ascaris
b) Wuchereria
c) Taenia solium / Taenia saginata
d) Ancylostoma
Answer: c) Taenia solium / Taenia saginata
Explanation: Pork tapeworm (T. solium) and beef tapeworm (T. saginata) cause taeniasis.
69. Hydatid disease is caused by:
a) Echinococcus granulosus
b) Ascaris
c) Wuchereria
d) Trichinella
Answer: a) Echinococcus granulosus
Explanation: Dog tapeworm forms hydatid cysts in liver/lungs.
70. Trichinosis is caused by:
a) Trichinella spiralis
b) Ascaris
c) Taenia
d) Hookworm
Answer: a) Trichinella spiralis
Explanation: Nematode infection acquired from undercooked pork.
71. Guinea worm disease is caused by:
a) Dracunculus medinensis
b) Taenia
c) Ascaris
d) Hookworm
Answer: a) Dracunculus medinensis
Explanation: Transmitted by drinking water containing infected Cyclops.
72. Which is the intermediate host of Guinea worm?
a) Mosquito
b) Cyclops (water flea)
c) Housefly
d) Sandfly
Answer: b) Cyclops (water flea)
Explanation: Cyclops acts as vector/intermediate host of Dracunculus.
73. Schistosomiasis (bilharzia) is caused by:
a) Roundworm
b) Flatworm (Schistosoma)
c) Hookworm
d) Filarial worm
Answer: b) Flatworm (Schistosoma)
Explanation: Blood fluke causes schistosomiasis, common in Africa.
74. The vector of Japanese encephalitis is:
a) Sandfly
b) Culex mosquito
c) Anopheles mosquito
d) Housefly
Answer: b) Culex mosquito
Explanation: Culex mosquitoes transmit Japanese encephalitis virus.
75. The housefly transmits diseases like:
a) Cholera, Typhoid, Dysentery
b) Malaria
c) Filariasis
d) Sleeping sickness
Answer: a) Cholera, Typhoid, Dysentery
Explanation: Housefly spreads pathogens mechanically by contaminating food.
76. Deficiency of Vitamin A causes:
a) Rickets
b) Scurvy
c) Night blindness
d) Pellagra
Answer: c) Night blindness
Explanation: Vitamin A is essential for rhodopsin in eyes; deficiency impairs vision in dim light.
77. Deficiency of Vitamin D causes:
a) Beriberi
b) Pellagra
c) Rickets
d) Night blindness
Answer: c) Rickets
Explanation: Vitamin D deficiency causes soft, weak bones in children (rickets).
78. Deficiency of Vitamin C causes:
a) Pellagra
b) Scurvy
c) Beriberi
d) Rickets
Answer: b) Scurvy
Explanation: Vitamin C deficiency → bleeding gums, loose teeth, poor wound healing.
79. Deficiency of Vitamin K causes:
a) Bone deformity
b) Night blindness
c) Excessive bleeding
d) Pellagra
Answer: c) Excessive bleeding
Explanation: Vitamin K is needed for clotting factors; deficiency delays blood clotting.
80. Deficiency of Vitamin B1 (Thiamine) causes:
a) Pellagra
b) Beriberi
c) Scurvy
d) Night blindness
Answer: b) Beriberi
Explanation: Beriberi affects nervous system and heart due to lack of thiamine.
81. Deficiency of Vitamin B3 (Niacin) causes:
a) Pellagra
b) Beriberi
c) Rickets
d) Scurvy
Answer: a) Pellagra
Explanation: Pellagra shows 3 Ds: diarrhea, dermatitis, dementia.
82. Deficiency of Vitamin B12 causes:
a) Pernicious anemia
b) Rickets
c) Scurvy
d) Pellagra
Answer: a) Pernicious anemia
Explanation: Lack of B12 prevents normal RBC formation.
83. Deficiency of iron causes:
a) Goiter
b) Anemia
c) Rickets
d) Scurvy
Answer: b) Anemia
Explanation: Iron is essential for hemoglobin; deficiency causes anemia.
84. Deficiency of iodine causes:
a) Anemia
b) Goiter
c) Rickets
d) Scurvy
Answer: b) Goiter
Explanation: Iodine deficiency enlarges thyroid gland → goiter.
85. Kwashiorkor is caused by deficiency of:
a) Vitamins
b) Proteins
c) Fats
d) Carbohydrates
Answer: b) Proteins
Explanation: Protein deficiency → swollen belly, edema in children.
86. Marasmus is caused by deficiency of:
a) Only proteins
b) Energy (proteins + calories)
c) Only vitamins
d) Only minerals
Answer: b) Energy (proteins + calories)
Explanation: Severe calorie + protein deficiency → muscle wasting, weakness.
87. Diabetes mellitus is due to deficiency of:
a) Insulin
b) Glucagon
c) Thyroxine
d) Cortisol
Answer: a) Insulin
Explanation: Lack of insulin from pancreas → high blood sugar.
88. Which organ is affected in diabetes mellitus?
a) Liver
b) Pancreas
c) Kidney
d) Heart
Answer: b) Pancreas
Explanation: Beta cells of pancreas fail to produce enough insulin.
89. Hypertension is:
a) Low blood sugar
b) High blood pressure
c) High cholesterol
d) Weak bones
Answer: b) High blood pressure
Explanation: Hypertension is persistent BP above 140/90 mmHg.
90. Arteriosclerosis is caused by:
a) Hardening of arteries due to fat deposition
b) Weak bones
c) Vitamin deficiency
d) Low BP
Answer: a) Hardening of arteries due to fat deposition
Explanation: Cholesterol builds up in arteries → reduced elasticity.
91. Cancer is caused by:
a) Bacteria
b) Uncontrolled cell division
c) Virus only
d) Fungi
Answer: b) Uncontrolled cell division
Explanation: Cancer results from abnormal cell growth forming tumors.
92. Which cancer affects white blood cells?
a) Carcinoma
b) Leukemia
c) Sarcoma
d) Melanoma
Answer: b) Leukemia
Explanation: Leukemia is blood cancer involving WBCs.
93. Which cancer affects skin pigment cells?
a) Carcinoma
b) Melanoma
c) Sarcoma
d) Leukemia
Answer: b) Melanoma
Explanation: Melanoma arises from pigment-producing cells of skin.
94. Sickle cell anemia is caused by:
a) Vitamin deficiency
b) Mutation in hemoglobin gene
c) Lack of iron
d) Lack of vitamin B12
Answer: b) Mutation in hemoglobin gene
Explanation: Genetic disorder producing abnormal sickle-shaped RBCs.
95. Hemophilia is:
a) Excessive RBC production
b) Inability of blood to clot
c) Weak bones
d) Vitamin deficiency
Answer: b) Inability of blood to clot
Explanation: Hemophilia is a hereditary X-linked disorder where blood fails to clot.
96. Down syndrome is caused by:
a) Lack of vitamins
b) Trisomy of chromosome 21
c) Deficiency of hormones
d) Viral infection
Answer: b) Trisomy of chromosome 21
Explanation: Extra chromosome 21 causes Down syndrome (genetic disorder).
97. Thalassemia is:
a) Vitamin deficiency
b) Genetic disorder affecting hemoglobin synthesis
c) Iron overload disease
d) Viral infection
Answer: b) Genetic disorder affecting hemoglobin synthesis
Explanation: Thalassemia reduces hemoglobin production, causing anemia.
98. Alzheimer’s disease affects:
a) Heart
b) Lungs
c) Brain
d) Kidneys
Answer: c) Brain
Explanation: Alzheimer’s is a neurodegenerative disease causing memory loss.
99. Osteoporosis is caused by deficiency of:
a) Calcium & Vitamin D
b) Iron
c) Iodine
d) Vitamin C
Answer: a) Calcium & Vitamin D
Explanation: Osteoporosis = weak bones due to lack of calcium and vitamin D.
100. The first antibiotic discovered for bacterial diseases was:
a) Streptomycin
b) Penicillin
c) Tetracycline
d) Chloramphenicol
Answer: b) Penicillin
Explanation: Penicillin, discovered by Alexander Fleming in 1928, was the first antibiotic.