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Q1Science·Disease, Immunity and Public HealthPYQ 2023
'Wolbachia method' is sometimes talked about with reference to which one of the following?
- AControlling the viral diseases spread by mosquitoesCorrect
- BConverting crop residues into packing material
- CProducing biodegradable plastics
- DProducing biochar from thermo-chemical conversion of biomass
Explanation
Correct. Wolbachia are intracellular bacteria introduced into Aedes aegypti mosquitoes to reduce their ability to transmit dengue, Zika, and chikungunya viruses.
Why the other options are incorrect
- Option B
Wolbachia has no connection to crop-residue processing; it is a biological method targeting mosquito-borne viral diseases.
- Option C
Biodegradable plastics are produced from PLA or PHA polymers, not from Wolbachia bacteria.
- Option D
Biochar production involves pyrolysis of biomass and is unrelated to the Wolbachia approach used in vector control.
Q2Science·Disease, Immunity and Public HealthPYQ 2021
In the context of hereditary diseases, consider the following statements:
1. Passing on mitochondrial diseases from parent to child can be prevented by mitochondrial replacement therapy either before or after in vitro fertilisation of the egg.
2. A child inherits mitochondrial diseases entirely from mother and not from father.
Which of the statements given above is/are correct?
- A1 only
- B2 only
- CBoth 1 and 2Correct
- DNeither 1 nor 2
Explanation
Correct. Mitochondrial replacement therapy prevents passage of defective mitochondria, and mitochondrial DNA is inherited maternally since mitochondria in sperm are destroyed after fertilisation.
Why the other options are incorrect
- Option A
Statement 2 is also correct because mitochondria are inherited exclusively through the ovum; sperm contribute negligible mitochondria.
- Option B
Statement 1 is also correct; mitochondrial replacement therapy (pronuclear or spindle transfer) can be performed before or after IVF to prevent transmission.
- Option D
Both statements are factually accurate based on current understanding of mitochondrial inheritance and assisted reproductive technologies.
Q3Science·Disease, Immunity and Public HealthPYQ 2019
Which one of the following statements is not correct?
- AHepatitis B virus is transmitted much like HIV.
- BHepatitis B, unlike Hepatitis C, does not have a vaccine.Correct
- CGlobally, the number of people infected with Hepatitis B and C viruses are several times more than those infected with HIV.
- DSome of those infected with Hepatitis B and C viruses do not show the symptoms for many years.
Explanation
Correct (not correct statement). Hepatitis B does have a highly effective vaccine; it is Hepatitis C that currently lacks a vaccine.
Why the other options are incorrect
- Option A
This is correct; both Hepatitis B and HIV spread through blood, sexual contact, and mother-to-child transmission.
- Option C
This is correct; WHO estimates roughly 350 million chronic HBV and 70 million HCV carriers versus about 38 million living with HIV.
- Option D
This is correct; both infections can remain asymptomatic for years or decades before liver damage becomes apparent.
Q4Science·Disease, Immunity and Public HealthPYQ 2017
Consider the following statements:
1. In tropical regions, Zika virus disease is transmitted by the same mosquito that transmits dengue.
2. Sexual transmission of Zika virus disease is possible.
Which of the statements given above is/are correct?
- A1 only
- B2 only
- CBoth 1 and 2Correct
- DNeither 1 nor 2
Explanation
Correct. Aedes aegypti is the primary vector for both Zika and dengue in the tropics, and Zika can also spread through sexual contact.
Why the other options are incorrect
- Option A
Statement 2 is also correct; Zika virus has been detected in semen and documented cases of sexual transmission exist.
- Option B
Statement 1 is also correct; Aedes aegypti transmits both Zika and dengue in tropical regions.
- Option D
Both statements are well-established facts confirmed by WHO and CDC during the 2015-2016 Zika outbreak.
Q5Science·Disease, Immunity and Public HealthPYQ 2015
H1N1 virus is sometimes mentioned in the news with reference to which one of the following diseases?
- AAIDS
- BBird flu
- CDengue
- DSwine fluCorrect
Explanation
Correct. H1N1 is the influenza A subtype responsible for swine flu, which caused the 2009 global pandemic.
Why the other options are incorrect
- Option A
AIDS is caused by HIV (Human Immunodeficiency Virus), not by any influenza strain.
- Option B
Bird flu is caused by H5N1 or H7N9 strains of influenza A, not by H1N1.
- Option C
Dengue is caused by the dengue virus transmitted by Aedes mosquitoes, not by an influenza virus.
Q6Science·Disease, Immunity and Public HealthPYQ 2014
Consider the following diseases:
1. Diphtheria
2. Chickenpox
3. Smallpox
Which of the above diseases has/have been eradicated in India?
- A1 and 2 only
- B3 onlyCorrect
- C1, 2 and 3
- DNone
Explanation
Correct. Smallpox was declared eradicated globally in 1980 by WHO; India's last case was in 1975. Diphtheria and chickenpox remain endemic.
Why the other options are incorrect
- Option A
Diphtheria still occurs in India despite vaccination, and chickenpox cases continue to be reported regularly.
- Option C
Only smallpox has been eradicated; diphtheria and chickenpox cases are still reported in India.
- Option D
Smallpox has been eradicated both in India and worldwide, so 'none' is incorrect.
Q7Science·Disease, Immunity and Public HealthPYQ 2014
Consider the following pairs:
Vitamin — Deficiency disease
1. Vitamin C — Scurvy
2. Vitamin D — Rickets
3. Vitamin E — Night blindness
Which of the pairs given above is/are correctly matched?
- A1 and 2 onlyCorrect
- B3 only
- C1, 2 and 3
- DNone
Explanation
Correct. Vitamin C deficiency causes scurvy and Vitamin D deficiency causes rickets; Vitamin E deficiency causes neurological problems, not night blindness.
Why the other options are incorrect
- Option B
Pair 3 is wrong because night blindness is caused by Vitamin A deficiency, not Vitamin E deficiency.
- Option C
Pair 3 is incorrect; night blindness (nyctalopia) results from Vitamin A deficiency, while Vitamin E deficiency leads to hemolytic anaemia and nerve damage.
- Option D
Pairs 1 and 2 are correctly matched; scurvy is linked to Vitamin C and rickets to Vitamin D.
Q8Science·Disease, Immunity and Public HealthPYQ 2013
Which of the following diseases can be transmitted from one person to another through transfusion of blood?
1. Chikungunya
2. Hepatitis B
3. HIV-AIDS
Select the correct answer using the codes given below.
- A1 only
- B2 and 3 onlyCorrect
- C1 and 3 only
- D1, 2 and 3
Explanation
Correct. Hepatitis B and HIV are well-known blood-borne infections that can transmit through transfusion; chikungunya, though a viraemic infection, is not a standard transfusion-transmitted disease.
Why the other options are incorrect
- Option A
Chikungunya is primarily transmitted by Aedes mosquitoes, not through blood transfusion under standard screening protocols.
- Option C
Chikungunya is not a recognised transfusion-transmissible infection in clinical practice, unlike HIV.
- Option D
Chikungunya is a mosquito-borne viral disease and is not classified among standard transfusion-transmitted infections.
Q9Science·Disease, Immunity and Public HealthPYQ 2010
Widespread resistance of malarial parasites to drugs like chloroquine has prompted attempts to develop a malaria vaccine to combat malaria. Why is it difficult to develop an effective malaria vaccine?
- AMalaria is caused by several species of Plasmodium.Correct
- BMan does not develop immunity to malaria during natural infection.
- CVaccines can be developed only against bacteria.
- DMan is only an intermediate host and not the definitive host.
Explanation
Correct. Multiple Plasmodium species (P. falciparum, P. vivax, P. malariae, P. ovale) with antigenic variation make it extremely difficult to design a single effective vaccine.
Why the other options are incorrect
- Option B
Humans do develop partial immunity after repeated exposure in endemic areas, so this statement is incorrect.
- Option C
Vaccines have been developed against viruses, parasites, and fungi as well, not just bacteria.
- Option D
While the mosquito is the definitive host, the difficulty in vaccine development relates to antigenic diversity, not host classification.
Q10Science·Disease, Immunity and Public HealthPYQ 2010
With regard to the transmission of the Human Immunodeficiency Virus, which one of the following statements is not correct?
- AThe chances of transmission from female to male are twice as likely as from male to female.Correct
- BThe chances of transmission are more if a person suffers from other sexually transmitted infections.
- CAn infected mother can transmit the infection during pregnancy, at childbirth and by breastfeeding.
- DThe risk of contracting infection from transfusion of infected blood is much higher than an exposure to contaminated needle.
Explanation
Correct (not correct statement). Epidemiological data shows that male-to-female transmission is actually more likely due to greater mucosal exposure, not the reverse.
Why the other options are incorrect
- Option B
This is correct; co-infection with STIs like syphilis or herpes increases HIV transmission risk due to genital ulcers and inflammation.
- Option C
This is correct; vertical transmission can occur in utero, during delivery, or through breast milk.
- Option D
This is correct; transfusion of infected blood carries over 90% transmission risk, far higher than needlestick exposure (~0.3%).
Q11Science·Disease, Immunity and Public HealthPYQ 1999
Which one of the following genetic diseases is sex-linked?
- ARoyal haemophiliaCorrect
- BTay-Sachs disease
- CCystic fibrosis
- DHypertension
Explanation
Correct. Royal haemophilia (Haemophilia B) is an X-linked recessive disorder famously traced through European royal families from Queen Victoria.
Why the other options are incorrect
- Option B
Tay-Sachs disease is an autosomal recessive disorder caused by a mutation on chromosome 15, not sex-linked.
- Option C
Cystic fibrosis is an autosomal recessive condition involving a mutation in the CFTR gene on chromosome 7.
- Option D
Hypertension is a multifactorial condition influenced by many genes and environmental factors, not a sex-linked genetic disease.
Q12Science·Disease, Immunity and Public HealthPYQ 1996
AIDS is transmitted:
I. By sexual contact.
II. By blood transfusion.
III. By mosquitoes and other blood sucking insects.
IV. Across the placenta.
Of these statements
- AI, II and III are correct
- BI, II and IV are correctCorrect
- CI, III and IV are correct
- DI and III are correct
Explanation
Correct. HIV transmits through sexual contact (I), blood transfusion (II), and across the placenta from mother to child (IV); mosquitoes cannot transmit HIV.
Why the other options are incorrect
- Option A
Statement III is incorrect; HIV does not survive or replicate in mosquitoes, and no evidence supports insect-borne transmission.
- Option C
Statement III is wrong; HIV is not transmitted by mosquitoes or other blood-sucking insects.
- Option D
This excludes placental transmission (IV), which is a well-established route of vertical HIV transmission.