1. The causative organism of tuberculosis (TB) is ___________.
A) Salmonella typhi
B) Mycobacterium tuberculosis
C) Vibrio cholerae
D) Clostridium tetani
Answer: B
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
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
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
Explanation: Widal test detects antibodies against Salmonella typhi.
5. Cholera is caused by___________.
A) Vibrio cholerae
B) Salmonella
C) Streptococcus
D) Plasmodium
Answer: A
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
Explanation: ELISA test detects antibodies against HIV.
29. Polio is caused by___________.
A) HIV
B) Polio virus
C) Adenovirus
D) Influenza virus
Answer: B
Explanation: Polio is caused by poliovirus (Picornavirus family).
30. Polio affects primarily___________.
A) Heart
B) Brain
C) Nervous system
D) Lungs
Answer: C
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
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
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
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
Explanation: Pasteur developed the first rabies vaccine in 1885.
35. Hepatitis affects mainly___________.
A) Heart
B) Lungs
C) Liver
D) Kidneys
Answer: C
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
Explanation: Sandfly transmits Leishmania.
58. Sleeping sickness is caused by___________.
A) Entamoeba
B) Trypanosoma gambiense
C) Leishmania
D) Giardia
Answer: B
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
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
Explanation: Amoebiasis spreads through contaminated food and water.
61. Giardiasis is caused by___________.
A) Giardia lamblia
B) Entamoeba
C) Trypanosoma
D) Leishmania
Answer: A
Explanation: Giardia causes diarrhea and malabsorption.
62. Trichomoniasis is caused by___________.
A) Trichomonas vaginalis
B) Entamoeba
C) Plasmodium
D) Giardia
Answer: A
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
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
Explanation: Culex mosquito spreads filarial worm.
65. Ascariasis is caused by___________.
A) Taenia
B) Ascaris lumbricoides
C) Trichinella
D) Ancylostoma
Answer: B
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
Explanation: Lack of B12 prevents normal RBC formation.
83. Deficiency of iron causes___________.
A) Goiter
B) Anemia
C) Rickets
D) Scurvy
Answer: B
Explanation: Iron is essential for hemoglobin; deficiency causes anemia.
84. Deficiency of iodine causes___________.
A) Anemia
B) Goiter
C) Rickets
D) Scurvy
Answer: B
Explanation: Iodine deficiency enlarges thyroid gland → goiter.
85. Kwashiorkor is caused by deficiency of___________.
A) Vitamins
B) Proteins
C) Fats
D) Carbohydrates
Answer: B
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
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
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
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
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
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
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
Explanation: Leukemia is blood cancer involving WBCs.
93. Which cancer affects skin pigment cells?
A) Carcinoma
B) Melanoma
C) Sarcoma
D) Leukemia
Answer: B
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
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
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
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
Explanation: Thalassemia reduces hemoglobin production, causing anemia.
98. Alzheimer’s disease affects___________.
A) Heart
B) Lungs
C) Brain
D) Kidneys
Answer: C
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
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
Explanation: Penicillin, discovered by Alexander Fleming in 1928, was the first antibiotic.