Diseases & Immunity – NDA Biology PYQs

NDA 2025-II

Q. 1. Which one of the following blood cells type secrete large number of antibodies during an immune response of the body?

(a) Neutrophils

(b) Eosinophils

(c) Lymphocytes

(d) Monocytes

Answer: (c) Lymphocytes

Explanation: During an immune response, B lymphocytes are activated by antigens and differentiate into plasma cells, which secrete large quantities of specific antibodies. These antibodies bind to and neutralise the antigen. Neutrophils are the most abundant white blood cells and are the first responders to infection: they engulf pathogens but do not produce antibodies. Eosinophils combat parasites and allergic reactions. Monocytes differentiate into macrophages and dendritic cells. Concept Tested: B lymphocytes (plasma cells) secrete antibodies during immune response

NDA 2025-I

Q. 2. Initial discovery of antibiotic penicillin was done by

(a) Francis Crick

(b) Maurice Wilkins

(c) Charles Darwin

(d) Alexander Fleming

Answer: (d) Alexander Fleming

Explanation: Alexander Fleming discovered penicillin in 1928 when he noticed that a mould (Penicillium notatum) was inhibiting the growth of Staphylococcus bacteria on an agar plate. This accidental observation led to the development of the first antibiotic. Francis Crick and Maurice Wilkins were involved in discovering the structure of DNA. Charles Darwin proposed the theory of evolution. Concept Tested: Alexander Fleming discovered penicillin (1928) from Penicillium mould

Q. 3. The vector of malaria parasites is

(a) Male Anopheles mosquito

(b) Male Culex mosquito

(c) Female Anopheles mosquito

(d) Female Culex mosquito

Answer: (c) Female Anopheles mosquito

Explanation: Only the female Anopheles mosquito transmits the malarial parasite Plasmodium. Female mosquitoes require blood meals to develop eggs; this is when Plasmodium enters the human body. Male mosquitoes feed only on nectar and plant fluids. Culex mosquitoes transmit filariasis (elephantiasis) and some viral encephalitis, not malaria. Concept Tested: Female Anopheles mosquito: the vector of the malarial parasite Plasmodium

★ JOVIK Exam Insight NDA repeatedly tests malaria vector and pathogen. Vector = Female Anopheles mosquito. Pathogen = Plasmodium (a protozoan). Culex mosquito transmits filariasis (Wuchereria bancrofti). Aedes aegypti transmits dengue and chikungunya.

Q. 4. Which of the following pairs is/are correctly matched?

1. Malaria  :  Mycobacterium

2. TB  :  Plasmodium

Select the answer using the code given below:

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

Answer: (d) Neither 1 nor 2

Explanation: Both pairs are incorrectly matched. Malaria is caused by Plasmodium (a protozoan), not Mycobacterium. Tuberculosis (TB) is caused by Mycobacterium tuberculosis (a bacterium), not Plasmodium. The pairs are swapped: both are wrong. The correct matches are: Malaria → Plasmodium; TB → Mycobacterium tuberculosis. Concept Tested: Malaria → Plasmodium (protozoan); TB → Mycobacterium tuberculosis (bacterium); the pairs in this question are both incorrect

NDA 2024-I

Q. 5. Which one among the following cells produces antibodies against a foreign antigen?

(a) Lymphocytes

(b) Erythrocytes

(c) Eosinophils

(d) Platelets

Answer: (a) Lymphocytes

Explanation: Lymphocytes, specifically B lymphocytes, are responsible for producing antibodies (immunoglobulins) in response to foreign antigens. When a B cell encounters its specific antigen, it differentiates into a plasma cell that secretes large quantities of antibodies. T lymphocytes coordinate the immune response but do not directly produce antibodies. Erythrocytes carry oxygen. Eosinophils target parasites and are involved in allergies. Platelets are involved in blood clotting. Concept Tested: B lymphocytes produce antibodies in response to foreign antigens

NDA 2023-II

Q. 6. An important cause of tooth decay by the bacterium Streptococcus mutans is because of their ability to attach to teeth surface by producing slime layer from

(a) Sugar

(b) Alcohol

(c) Saliva

(d) Teichoic acid

Answer: (a) Sugar

Explanation: Streptococcus mutans is the primary bacterium responsible for dental caries. It produces a sticky slime layer (glucan/dextran) from dietary sugars: especially sucrose: using the enzyme glucosyltransferase. This biofilm (dental plaque) allows the bacteria to adhere firmly to the tooth surface. The bacteria then ferment sugars to produce lactic acid, which demineralises tooth enamel. This is why a high-sugar diet significantly increases the risk of tooth decay. Concept Tested: Streptococcus mutans produces slime layer from sugar to attach to teeth, causing dental caries

NDA 2023-I

Q. 7. Which one of the following is not a characteristic feature of fungi?

(a) Cell wall is made of chitin

(b) Filamentous mycelium is present

(c) Can carry out photosynthesis

(d) Asexual spores are produced

Answer: (c) Can carry out photosynthesis

Explanation: Fungi are heterotrophic organisms: they cannot carry out photosynthesis. They obtain nutrients by absorbing organic material from their environment (saprotrophic or parasitic nutrition). Fungi do have cell walls made of chitin (unlike plant cell walls made of cellulose). Most fungi have a filamentous body called mycelium. They reproduce by producing asexual spores. The inability to photosynthesise is what distinguishes fungi from plants and algae. Concept Tested: Fungi cannot photosynthesise; they are heterotrophs that absorb nutrition

NDA 2022-I

Q. 8. Which one of the following is caused by a bacterial pathogen?

(a) AIDS

(b) Dengue fever

(c) COVID-19

(d) Typhoid fever

Answer: (d) Typhoid fever

Explanation: Typhoid fever is caused by Salmonella typhi, a gram-negative bacterium. It spreads through contaminated food and water. AIDS is caused by HIV (a retrovirus). Dengue is caused by the Dengue virus (a flavivirus). COVID-19 is caused by SARS-CoV-2 (a coronavirus). Typhoid is the only bacterial disease among the four options. Concept Tested: Typhoid fever caused by Salmonella typhi (bacterium); AIDS, dengue, COVID-19 are viral

NDA 2021-II

Q. 9. Which one of the following viruses used to be responsible for highly infectious disease Smallpox?

(a) Adenovirus

(b) Variola virus

(c) Aichi virus

(d) Coxsackie virus

Answer: (b) Variola virus

Explanation: Smallpox was caused by the Variola virus, a member of the Orthopoxvirus genus. It was one of the most devastating diseases in human history. Smallpox was declared eradicated by the WHO in 1980 following a global vaccination campaign. It is the only human infectious disease that has been completely eradicated. Adenovirus causes respiratory infections. Aichi virus and Coxsackie virus cause gastrointestinal and other infections. Concept Tested: Smallpox was caused by the Variola virus; eradicated in 1980

NDA 2020

Q. 10. Which one of the following statements is correct about effects of antibiotics on viruses?

(a) Viruses are “non-living” entities but it can interact with antibiotics

(b) Taking antibiotics cures viral infections

(c) Viruses do not possess metabolic pathways on which antibiotics can function, whereas bacteria have such pathways

(d) Viruses are resistant to antibiotics

Answer: (c) Viruses do not possess metabolic pathways on which antibiotics can function, whereas bacteria have such pathways

Explanation: Antibiotics target specific bacterial structures or metabolic pathways: such as cell wall synthesis (penicillin), protein synthesis (streptomycin), or DNA replication (fluoroquinolones). Viruses do not have cell walls, ribosomes, or independent metabolism. Therefore, antibiotics have nothing to act on in a virus. Option (d) is misleading: viruses are not “resistant”; they simply lack the target structures. Option (c) correctly identifies the scientific reason. Concept Tested: Antibiotics do not work on viruses because viruses lack the metabolic pathways and structures that antibiotics target

★ JOVIK Exam Insight A common misconception is that antibiotics cure all infections. Antibiotics ONLY work on bacteria. They have no effect on viruses (influenza, common cold, COVID-19, dengue). Taking antibiotics for viral infections is not just ineffective: it promotes antibiotic resistance.

NDA 2019-II

Q. 11. Which one of the following is a bacterium that causes disease in the human body?

(a) Varicella zoster

(b) Trypanosoma gambiense

(c) Salmonella typhi

(d) Plasmodium falciparum

Answer: (c) Salmonella typhi

Explanation: Salmonella typhi is a gram-negative bacterium that causes typhoid fever. It spreads through contaminated food and water. Varicella zoster is a virus (causes chickenpox and shingles). Trypanosoma gambiense is a protozoan (causes sleeping sickness). Plasmodium falciparum is a protozoan (causes the most severe form of malaria). Concept Tested: Salmonella typhi: bacterium causing typhoid fever; other options are virus or protozoa

Q. 12. Which one of the following statements regarding viruses is not true?

(a) Viruses need living cells to reproduce.

(b) All viruses are parasites.

(c) Viruses can synthesize their food through photosynthesis.

(d) Viruses are similar to chemical substances outside the host.

Answer: (c) Viruses can synthesize their food through photosynthesis.

Explanation: Viruses cannot carry out photosynthesis. They have no metabolism of their own outside a host cell. Viruses are obligate intracellular parasites: they can only reproduce inside living cells (Statement a and b are correct). Outside a host, viruses behave like inert chemical substances (Statement d is correct). The statement that viruses can photosynthesise is false: they lack the necessary organelles and machinery. Concept Tested: Viruses cannot photosynthesise; they are obligate intracellular parasites with no independent metabolism

NDA 2019-I

Q. 13. Which one of the following statements regarding Penicillin is correct?

(a) Penicillin resistant bacteria can store this antibiotic in vacuole

(b) Penicillin resistant bacteria can degrade this antibiotic by an enzyme called β-lactamase

(c) Penicillin resistant bacteria can degrade this antibiotic by an enzyme called lactic acid dehydrogenase

(d) Penicillin is not absorbed by bacteria; so most bacteria are resistant

Answer: (b) Penicillin resistant bacteria can degrade this antibiotic by an enzyme called β-lactamase

Explanation: Penicillin works by inhibiting the synthesis of bacterial cell walls. Penicillin-resistant bacteria produce an enzyme called β-lactamase (penicillinase), which breaks the β-lactam ring in the penicillin molecule, rendering it inactive. This is the primary mechanism of penicillin resistance. Lactic acid dehydrogenase is a metabolic enzyme unrelated to antibiotic resistance. Bacteria do not store antibiotics in vacuoles (bacteria have no vacuoles). Concept Tested: Penicillin resistance: bacteria produce β-lactamase enzyme to degrade penicillin

Q. 14. Which one of the following statements regarding Cholera is correct?

(a) Cholera is a disease that causes loss of memory

(b) Cholera is a disease of muscles due to consumption of alcohol

(c) Cholera is a disease due to consumption of contaminated food or water

(d) Cholera is a genetic disease

Answer: (c) Cholera is a disease due to consumption of contaminated food or water

Explanation: Cholera is an acute diarrhoeal disease caused by the bacterium Vibrio cholerae. It is transmitted through contaminated food or water: particularly water contaminated with faecal matter. The toxin produced by V. cholerae causes massive loss of fluids and electrolytes through the intestine. Without treatment, severe cholera can be fatal. It is neither genetic nor caused by alcohol consumption. Concept Tested: Cholera: waterborne disease caused by Vibrio cholerae; spread through contaminated food or water

NDA 2018-II

Q. 15. Which one of the following is a waterborne disease?

(a) Jaundice

(b) Tuberculosis

(c) Rabies

(d) Arthritis

Answer: (a) Jaundice

Explanation: Jaundice (specifically infectious hepatitis/hepatitis A) can be waterborne: spread through water or food contaminated with the hepatitis A virus. Tuberculosis spreads through the air via respiratory droplets. Rabies spreads through the bite of infected animals. Arthritis is a non-infectious inflammatory joint condition. Among the options, jaundice is the waterborne disease. Concept Tested: Jaundice (hepatitis A) can be a waterborne disease; TB is airborne; rabies is from animal bites

NDA 2018-I

Q. 16. AIDS is caused by a virus whose genetic material is

(a) single stranded circular DNA

(b) double stranded DNA

(c) single stranded RNA

(d) double stranded RNA

Answer: (c) single stranded RNA

Explanation: HIV (Human Immunodeficiency Virus) is a retrovirus. Its genetic material is single-stranded RNA (two identical copies). HIV also carries the enzyme reverse transcriptase, which copies its RNA genome into DNA inside the host cell. This DNA is then integrated into the host cell genome. The ability to convert RNA into DNA is what makes HIV a retrovirus. Concept Tested: HIV has single-stranded RNA as its genetic material; it is a retrovirus that uses reverse transcriptase

NDA 2017-II

Q. 17. Which one of the following is the scientific name of the causal organism of elephantiasis?

(a) Ascaris lumbricoides

(b) Culex pipiens

(c) Wuchereria bancrofti

(d) Fasciola hepatica

Answer: (c) Wuchereria bancrofti

Explanation: Elephantiasis (lymphatic filariasis) is caused by the parasitic nematode worm Wuchereria bancrofti. It is transmitted by the bite of infected Culex mosquitoes. The worm lives in the lymphatic system and blocks lymph flow, causing massive swelling of limbs and tissues. Ascaris lumbricoides causes ascariasis (roundworm infection). Culex pipiens is the mosquito vector, not the causative organism. Fasciola hepatica causes liver fluke infection. Concept Tested: Elephantiasis (filariasis) caused by Wuchereria bancrofti; transmitted by Culex mosquito

Q. 18. Which one of the following statements about microbes is not correct?

(a) They are used in sewage treatment plants.

(b) They are used in industrial fermenters for the production of beverages.

(c) No antibiotic has been obtained from any microbe.

(d) They are used to get many bioactive molecules for the treatment of diseases.

Answer: (c) No antibiotic has been obtained from any microbe.

Explanation: Option (c) is incorrect. Many antibiotics have been derived from microorganisms. The most famous example is penicillin, derived from the Penicillium mould. Streptomycin is derived from Streptomyces bacteria. Microbes are also used in sewage treatment, fermentation (for beer, wine, vinegar, yogurt), and for producing bioactive molecules such as statins and cyclosporin. Concept Tested: Antibiotics are derived from microbes (e.g., penicillin from Penicillium, streptomycin from Streptomyces)

Q. 19. The term ‘Probiotic’ is applied to

(a) Organic food

(b) Antacid

(c) Antibiotic

(d) Live microbial food supplement

Answer: (d) Live microbial food supplement

Explanation: Probiotics are live microorganisms (mainly bacteria and some yeasts) that, when consumed in adequate amounts, confer a health benefit to the host. They are found in fermented foods such as yogurt, kefir, sauerkraut, and kimchi, or as dietary supplements. Common probiotic species include Lactobacillus and Bifidobacterium. Probiotics are not antibiotics (which kill bacteria) or antacids (which neutralise stomach acid). Concept Tested: Probiotic: live microbial food supplement that confers health benefits

Q. 20. Which one of the following microbes causes acidification and curding of milk?

(a) Lactic Acid Bacillus

(b) Clostridium botulinum

(c) Vibrio cholerae

(d) Saccharomyces cerevisiae

Answer: (a) Lactic Acid Bacillus

Explanation: Lactic Acid Bacillus (Lactobacillus species) converts lactose in milk into lactic acid through fermentation. The increased acidity causes milk proteins (mainly casein) to coagulate and precipitate, resulting in curd formation. This process is the basis of yogurt and curd production. Clostridium botulinum causes botulism. Vibrio cholerae causes cholera. Saccharomyces cerevisiae is a yeast used in bread-making and alcohol fermentation. Concept Tested: Lactic Acid Bacillus (Lactobacillus): converts lactose to lactic acid, causing acidification and curd formation in milk

NDA 2017-I

Q. 21. Sleeping sickness is a parasitic disease of humans and other animals. It is caused by

(a) Histomonas

(b) Trypanosoma

(c) Angomonae

(d) Naegleria

Answer: (b) Trypanosoma

Explanation: African sleeping sickness (trypanosomiasis) is caused by the protozoan parasite Trypanosoma (specifically T. brucei gambiense and T. brucei rhodesiense). It is transmitted by the bite of the tsetse fly. The parasite crosses the blood-brain barrier, affecting the central nervous system and causing disruptions to the sleep cycle, neurological damage, and death if untreated. Naegleria is an amoeba that causes a different brain infection. Concept Tested: Sleeping sickness (African trypanosomiasis) caused by Trypanosoma; transmitted by tsetse fly

Q. 22. Dengue virus causes high fever, rashes and reduces the number of a particular type of blood cells. Those blood cells are

(a) Monocytes

(b) Platelets

(c) Eosinophils

(d) Neutrophils

Answer: (b) Platelets

Explanation: Dengue fever is characterised by a severe drop in platelet count (thrombocytopenia). Platelets are essential for blood clotting. In severe dengue (dengue haemorrhagic fever), the platelet count can fall dangerously low, causing bleeding under the skin (petechiae/rashes), internal bleeding, and circulatory failure. Monitoring platelet count is a key part of dengue management. Concept Tested: Dengue fever causes thrombocytopenia (reduction in platelet count), leading to bleeding tendency

NDA 2016-II

Q. 23. In which one of the following, methanogens, i.e., methane producing bacteria are not present?

(a) Rumen of cattle

(b) Aerobic environment

(c) Anaerobic sludge

(d) Excreta of cattle

Answer: (b) Aerobic environment

Explanation: Methanogens are strictly anaerobic archaea: they can only survive in the absence of oxygen. They are found in: the rumen of cattle (where they produce methane as a byproduct of cellulose fermentation), anaerobic sludge (sewage treatment), and the excreta (dung) of cattle (biogas plants exploit this). An aerobic environment: which contains oxygen: is hostile to methanogens. They cannot survive in oxygen-rich conditions. Concept Tested: Methanogens are strictly anaerobic; they are absent in aerobic (oxygen-containing) environments

Q. 24. Malarial parasite is a

(a) bacteria

(b) protozoa

(c) virus

(d) fungus

Answer: (b) protozoa

Explanation: The malarial parasite Plasmodium is a protozoan: specifically a single-celled eukaryotic organism belonging to the phylum Apicomplexa. There are several species: P. falciparum (most deadly), P. vivax, P. malariae, and P. ovale. Malaria is therefore a protozoal disease, not bacterial, viral, or fungal. Concept Tested: Plasmodium (malarial parasite) is a protozoan, not a bacterium, virus, or fungus

Q. 25. It is difficult to kill viruses because they

(a) consist of tough protein coat

(b) are very small in size

(c) lack cellular structure

(d) spend a lot of time inside the host’s cells

Answer: (d) spend a lot of time inside the host’s cells

Explanation: Viruses are difficult to target with antiviral drugs primarily because they spend most of their life cycle inside host cells. Since they use the host cell’s own machinery for replication, any drug that damages the virus also risks damaging the host cell. This makes it difficult to design drugs that selectively kill the virus without harming the patient. A tough protein coat and small size do not explain why killing viruses is specifically difficult. Concept Tested: Viruses are difficult to kill because they replicate inside host cells, making selective targeting difficult without harming the host

NDA 2016-I

Q. 26. Which of the commonly used household item(s) release Bisphenol A (BPA) which is an endocrine disruptor and bad for human health?

1. Steel utensils

2. Plastic coffee mugs

3. Aluminium utensils

4. Plastic water storage bottles

Select the correct answer using the code given below:

(a) 1 only

(b) 1 and 2 only

(c) 2 and 4 only

(d) 1, 2 and 3 only

Answer: (c) 2 and 4 only

Explanation: BPA (Bisphenol A) is an industrial chemical used in the production of certain plastics, particularly polycarbonate plastics and epoxy resins. It leaches into food and beverages from plastic containers, especially when heated. Items 2 (plastic coffee mugs) and 4 (plastic water storage bottles) are plastic products that may contain and release BPA. Steel and aluminium utensils do not contain BPA. Concept Tested: BPA (endocrine disruptor) is released from plastic items such as plastic mugs and water storage bottles; not from steel or aluminium

Q. 27. Which of the following pairs of vector and disease is/are correctly matched?

Vector :  Disease

1. Anopheles : Malaria

2. Aedes aegypti : Chikungunya

3. Tsetse fly : Filariasis

4. Bed bugs : Sleeping sickness

Select the correct answer using the code given below:

(a) 1, 2 and 3 only

(b) 1 and 2 only

(c) 1 and 4 only

(d) 2 only

Answer: (b) 1 and 2 only

Explanation: Pair 1 is correct: Anopheles mosquito transmits malaria. Pair 2 is correct: Aedes aegypti transmits dengue fever and chikungunya. Pair 3 is incorrect: the tsetse fly transmits sleeping sickness (trypanosomiasis), not filariasis. Filariasis is transmitted by Culex mosquitoes. Pair 4 is incorrect: sleeping sickness is transmitted by the tsetse fly, not bed bugs. Concept Tested: Anopheles → malaria; Aedes aegypti → dengue/chikungunya; Tsetse fly → sleeping sickness (NOT filariasis); Culex → filariasis

★ JOVIK Exam Insight The vector-disease table is a high-frequency NDA topic. Key pairings: Anopheles (female) → malaria. Aedes aegypti → dengue and chikungunya. Culex → filariasis (Wuchereria bancrofti). Tsetse fly → sleeping sickness (Trypanosoma). Do not confuse tsetse fly with filariasis.

NDA 2015-II

Q. 28. Who among the following discovered the antibiotic producing fungus from Penicillium genus?

(a) Louis Pasteur

(b) Sir Alexander Fleming

(c) Stanley Prusiner

(d) Robert Hooke

Answer: (b) Sir Alexander Fleming

Explanation: Sir Alexander Fleming discovered penicillin in 1928 when he observed that a Penicillium mould was lysing Staphylococcus colonies on an agar plate. This accidental discovery is one of the most important in medical history. Louis Pasteur developed germ theory and pasteurisation. Stanley Prusiner discovered prions. Robert Hooke first observed and named the cell. Concept Tested: Alexander Fleming discovered penicillin from Penicillium fungus (1928)

Q. 29. Which one of the following is not a site of action in human body for the malarial parasite plasmodium?

(a) Liver

(b) Kidney

(c) Red blood cell

(d) Brain

Answer: (b) Kidney

Explanation: Plasmodium has a complex life cycle in the human body. After injection by a mosquito bite, it first travels to the liver, where it undergoes asexual multiplication (exoerythrocytic stage). It then infects red blood cells (erythrocytic stage), where it continues to multiply and causes the characteristic fever cycles. In severe malaria (P. falciparum), infected RBCs can clog capillaries in the brain: causing cerebral malaria. The kidney is not a primary site of Plasmodium activity. Concept Tested: Plasmodium acts in liver, red blood cells, and brain (cerebral malaria); kidney is not a site of Plasmodium infection

NDA 2014-II

Q. 30. Leprosy is caused by

(a) virus

(b) bacteria

(c) protozoa

(d) retrovirus

Answer: (b) bacteria

Explanation: Leprosy (Hansen’s disease) is caused by Mycobacterium leprae, a slow-growing gram-positive bacterium. It primarily affects the skin, peripheral nerves, upper respiratory tract, and eyes. M. leprae was the first bacterium identified as causing disease in humans (discovered by Armauer Hansen in 1873). Leprosy is one of the oldest known diseases and is still present in parts of Asia, Africa, and South America. Concept Tested: Leprosy caused by Mycobacterium leprae (bacterium): Hansen’s disease

NDA 2014-I

Q. 31. What is ‘breakbone fever’ most commonly known as?

(a) Typhoid

(b) Rhinitis

(c) Yellow fever

(d) Dengue

Answer: (d) Dengue

Explanation: Dengue fever is popularly called ‘breakbone fever’ because of the severe muscle and joint pain it causes: patients describe it as feeling as though their bones are breaking. It is caused by the dengue virus (a flavivirus) and is transmitted by the Aedes aegypti mosquito. Typhoid is a bacterial gastrointestinal disease. Rhinitis is inflammation of the nasal lining. Yellow fever is a viral haemorrhagic fever transmitted by Aedes mosquitoes. Concept Tested: Dengue fever is known as ‘breakbone fever’ due to severe muscle and joint pain

Q. 32. Which one among the following is not a sexually transmitted disease?

(a) Syphilis

(b) Gonorrhea

(c) Scurvy

(d) Hepatitis B

Answer: (c) Scurvy

Explanation: Scurvy is a nutritional deficiency disease caused by a lack of vitamin C (ascorbic acid). It is not transmitted through sexual contact. Syphilis is caused by Treponema pallidum (a bacterium) and is a classic STD. Gonorrhea is caused by Neisseria gonorrhoeae (a bacterium) and is an STD. Hepatitis B is caused by the Hepatitis B virus and can be transmitted sexually (as well as through blood and vertical transmission). Concept Tested: Scurvy is a vitamin C deficiency disease, not an STD; syphilis, gonorrhea, and hepatitis B are STDs

NDA 2013-II

Q. 33. Which one among the following organs in humans is not involved in elicitation of immune response?

(a) Thymus

(b) Brain

(c) Spleen

(d) Lymph Nodes

Answer: (b) Brain

Explanation: The immune system organs include the thymus (where T lymphocytes mature), the spleen (filters blood and mounts immune responses), and lymph nodes (filter lymph and house immune cells). The brain is not part of the immune system. While the nervous and immune systems can interact (neuroimmunology), the brain itself does not directly elicit or carry out immune responses. Concept Tested: Brain is not an immune organ; thymus, spleen, and lymph nodes are involved in immune response

Q. 34. Which one among the following diseases is not caused by polluted water?

(a) Dysentery

(b) Jaundice

(c) Typhoid

(d) Tuberculosis

Answer: (d) Tuberculosis

Explanation: Tuberculosis (TB) is caused by Mycobacterium tuberculosis and spreads through the air via respiratory droplets from an infected person’s cough or sneeze. It is an airborne disease, not waterborne. Dysentery (bacterial or amoebic), typhoid (Salmonella typhi), and jaundice (hepatitis A) can all spread through contaminated water. Concept Tested: Tuberculosis is airborne (not waterborne); dysentery, typhoid, and jaundice can be waterborne

NDA 2013-I

Q. 35. Consider the following diseases:

1. Cholera

2. Tuberculosis

3. Filaria

4. Typhoid

Which of the above diseases are caused by bacteria?

(a) 1 and 3 only

(b) 2 and 4 only

(c) 1, 3 and 4

(d) 1, 2 and 4

Answer: (d) 1, 2 and 4

Explanation: Cholera is caused by Vibrio cholerae (bacterium). Tuberculosis is caused by Mycobacterium tuberculosis (bacterium). Typhoid is caused by Salmonella typhi (bacterium). All three are bacterial. Filaria is caused by Wuchereria bancrofti, a parasitic nematode worm: not a bacterium. Therefore 1 (Cholera), 2 (TB), and 4 (Typhoid) are bacterial diseases. Concept Tested: Bacterial diseases: cholera (Vibrio cholerae), TB (Mycobacterium), typhoid (Salmonella typhi); filaria is caused by a nematode worm

NDA 2012-II

Q. 36. Which one among the following waterborne diseases is not caused by a bacteria?

(a) Cholera

(b) Typhoid

(c) Bacillary dysentery

(d) Hepatitis A

Answer: (d) Hepatitis A

Explanation: Hepatitis A is caused by the Hepatitis A virus (HAV), not a bacterium. It spreads through contaminated food and water. Cholera is caused by Vibrio cholerae (bacterium). Typhoid is caused by Salmonella typhi (bacterium). Bacillary dysentery is caused by Shigella (bacterium). Hepatitis A stands out as a viral waterborne disease. Concept Tested: Hepatitis A is a viral waterborne disease; cholera, typhoid, and bacillary dysentery are bacterial waterborne diseases

Q. 37. After entering the human body through mosquito bite, the malarial parasite (plasmodium) shows initial multiplication in

(a) Spinal chord

(b) Blood

(c) Liver

(d) Spleen

Answer: (c) Liver

Explanation: When an infected female Anopheles mosquito bites a human, it injects Plasmodium sporozoites into the bloodstream. These sporozoites travel rapidly to the liver, where they invade liver cells (hepatocytes) and undergo initial multiplication (exoerythrocytic schizogony) over 1–2 weeks. The merozoites produced then enter the blood to infect red blood cells. The liver is where Plasmodium first multiplies in the human body. Concept Tested: Plasmodium first multiplies in the liver (exoerythrocytic stage) after entering the human body

Q. 38. Which one among the following is not included in the major clinical sign as a case definition of AIDS in children < 12 years of age?

(a) Persistent cough for more than 1 month

(b) Loss of weight

(c) Chronic diarrhoea

(d) Prolonged fever

Answer: (a) Persistent cough for more than 1 month

Explanation: The WHO clinical case definition for AIDS in children under 12 includes: loss of weight or failure to thrive, chronic diarrhoea, and prolonged fever: these are the three major signs. Persistent cough for more than one month is listed as a minor sign, not a major clinical sign, in several WHO paediatric AIDS case definitions. Among the options, persistent cough is not among the primary (major) clinical signs in the case definition. Concept Tested: WHO paediatric AIDS case definition: major signs are weight loss, chronic diarrhoea, prolonged fever; persistent cough is a minor sign

Q. 39. Polio disease is caused by

(a) Bacteria

(b) Fungi

(c) Virus

(d) Worm

Answer: (c) Virus

Explanation: Poliomyelitis (polio) is caused by the poliovirus, a member of the Enterovirus genus. It primarily spreads through faecal-oral contamination. The virus can infect the spinal cord and cause irreversible paralysis. Polio has been largely eradicated through widespread vaccination with OPV (oral polio vaccine) and IPV (inactivated polio vaccine). Concept Tested: Polio caused by the poliovirus; spread through faecal-oral route; preventable by vaccination

NDA 2011-II

Q. 40. The common edible mushroom is a

(a) mass of fungal spores

(b) type of hypha

(c) tightly packed mycelium

(d) structure used for producing asexual spores

Answer: (c) tightly packed mycelium

Explanation: The edible part of a mushroom (the visible fruiting body) is a densely packed mass of hyphae: the individual filamentous threads that make up a fungal body. The entire structure is called the basidiocarp or fruiting body. It is composed of tightly packed mycelium (interwoven hyphae). The fruiting body produces sexual spores (basidiospores) from its gills: not asexual spores. Option (d) is therefore also inaccurate; the mushroom produces sexual spores. Concept Tested: Edible mushroom is a tightly packed mass of hyphae (mycelium) forming the fungal fruiting body

Q. 41. AIDS is caused by Human Immunodeficiency Virus (HIV) which is

(a) Retro virus

(b) Lente virus

(c) Arbo virus

(d) Immune virus

Answer: (a) Retro virus

Explanation: HIV (Human Immunodeficiency Virus) is classified as a retrovirus. Retroviruses use the enzyme reverse transcriptase to convert their RNA genome into DNA, which is then integrated into the host cell genome. HIV is more specifically a lentivirus (a subgroup of retroviruses), but among the options, “Retro virus” is the correct broader classification. Arbovirus is a group of viruses transmitted by arthropods (mosquitoes, ticks). Concept Tested: HIV is a retrovirus (uses reverse transcriptase to convert RNA to DNA)

NDA 2010-I

Q. 42. Leishmania, the causative agent of kala-azar, multiplies asexually by

(a) budding

(b) binary fission

(c) multiple fission

(d) sporogony

Answer: (b) binary fission

Explanation: Leishmania is a protozoan parasite that causes kala-azar (visceral leishmaniasis). It reproduces asexually by binary fission: the organism divides into two daughter cells. This is the primary mode of asexual reproduction in most protozoa. Budding (producing an outgrowth), multiple fission (producing many cells simultaneously), and sporogony (spore formation) are other forms of asexual reproduction used by different organisms. Concept Tested: Leishmania (kala-azar) reproduces asexually by binary fission

Q. 43. Administering a vaccine provides protection by inducing synthesis of antibodies (proteins) specific to the vaccine. The cell in the body responsible for the production of antibodies is

(a) granulocyte

(b) lymphocyte

(c) erythrocyte (red blood cell)

(d) platelet

Answer: (b) lymphocyte

Explanation: Vaccines work by stimulating the adaptive immune response. The vaccine antigen is presented to B lymphocytes, which become activated and differentiate into plasma cells. Plasma cells are specialised B lymphocytes that produce large quantities of specific antibodies. Granulocytes (neutrophils, eosinophils, basophils) are innate immune cells. Erythrocytes carry oxygen. Platelets are involved in clotting. Concept Tested: Lymphocytes (B cells/plasma cells) produce antibodies in response to vaccines

Q. 44. To which one of the following types of organism do mushrooms belong?

(a) Algae

(b) Ferns

(c) Fungi

(d) Lichens

Answer: (c) Fungi

Explanation: Mushrooms are the fruiting bodies of certain species of fungi, primarily from the class Basidiomycetes. They are not plants, algae, or lichens. Fungi are heterotrophs that absorb nutrients from their environment. Algae are photosynthetic. Ferns are vascular plants. Lichens are a symbiotic association between a fungus and an alga or cyanobacterium. Concept Tested: Mushrooms are fungi (Basidiomycetes): not algae, plants, or lichens

NDA 2009-I

Q. 45. Oral Rehydration Therapy is recommended for patients suffering from

(a) Tuberculosis

(b) Typhoid

(c) Tetanus

(d) Cholera

Answer: (d) Cholera

Explanation: Cholera causes massive loss of fluids and electrolytes through severe watery diarrhoea. Oral Rehydration Therapy (ORT): drinking a solution of water, salt, and glucose: is the primary treatment for cholera. It replaces the lost fluids and electrolytes, preventing death from dehydration. Tuberculosis is treated with antibiotics. Tetanus is treated with antitoxin and antibiotics. Typhoid is treated with antibiotics. Concept Tested: Oral Rehydration Therapy (ORT) is the primary treatment for cholera to replace lost fluids

Q. 46. Match List I with List II and select the correct answer using the code given below the lists:

List I (Disease)  :   List II (Diagnosis)

A. AIDS       1. Widal test

B. Plague     2. Wayson stain test

C. Typhoid    3. ELISA test

4. Mantoux test

Code: A  B  C

List I (Disease)	List II (Diagnosis)
A. AIDS	1. Widal test
B. Plague	2. Wayson stain test
C. Typhoid	3. ELISA test
	4. Mantoux test

Code:

(a) 4    3    2

(b) 3    2    1

(c) 1    2    3

(d) 3    2    4

Answer: (b) 3    2    1

Explanation: AIDS is diagnosed by the ELISA test (Enzyme-Linked Immunosorbent Assay), which detects HIV antibodies: match A → 3. Plague (caused by Yersinia pestis) is identified using the Wayson stain test: match B → 2. Typhoid is diagnosed using the Widal test, which detects antibodies against Salmonella typhi: match C → 1. The Mantoux test (tuberculin skin test) is used to detect tuberculosis, not any of the three diseases listed. Concept Tested: Diagnostic tests: AIDS → ELISA; Plague → Wayson stain; Typhoid → Widal test; Mantoux test is for TB

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