Viral Diseases

11. Which of the following are the risk factors in the transmission of the

Which of the following are the risk factors in the transmission of the HIV infection ?

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  • 1. Smoking and drinking alcohol
  • 2. Observing bad hygiene
  • 3. Blood transfusion
  • 4. Unprotected sex

Select the correct answer using the code given below :

1 and 3 only
3 and 4 only
1, 3 and 4
1, 2 and 4
This question was previously asked in
UPSC CAPF – 2010
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The risk factors in the transmission of the HIV infection among the given options are Blood transfusion and Unprotected sex.
HIV is transmitted through specific bodily fluids: blood, semen, vaginal secretions, rectal fluids, and breast milk. Transmission routes primarily involve unprotected sexual contact (vaginal, anal, oral), sharing of needles or syringes, blood transfusions (rare in countries with screening), and from mother to child during pregnancy, childbirth, or breastfeeding. Smoking, drinking alcohol, and general bad hygiene are not direct routes of HIV transmission.
HIV is not transmitted through casual contact like touching, hugging, kissing, sharing utensils, using the same toilet, or mosquito bites. Understanding the actual transmission routes is crucial for prevention.

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12. Which one of the following viruses used to be responsible for highly i

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

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Adenovirus
Variola virus
Aichi virus
Coxsackie virus
This question was previously asked in
UPSC NDA-2 – 2021
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Smallpox was a devastating infectious disease caused by the Variola virus. It was eradicated globally by 1980 due to a successful vaccination campaign led by the World Health Organization.
The Variola virus is a member of the Orthopoxvirus genus, which also includes vaccinia virus and monkeypox virus. Smallpox caused a characteristic rash, fever, and often led to severe scarring or death.
Adenoviruses cause various illnesses, primarily respiratory infections. Aichi virus is an enterovirus linked to gastroenteritis. Coxsackie viruses are also enteroviruses known for causing hand, foot, and mouth disease, and other conditions.

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13. Which one of the following statements is correct about effects of anti

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

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Viruses are "non-living" entities but it can interact with antibiotics
Taking antibiotics cures viral infections
Viruses do not possess metabolic pathways on which antibiotics can function, whereas bacteria have such pathways
Viruses are resistant to antibiotics
This question was previously asked in
UPSC NDA-2 – 2020
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Antibiotics are designed to target specific structures or metabolic processes in bacteria, such as cell wall synthesis, protein synthesis (ribosomes), DNA replication, or specific enzymatic pathways. Viruses, being intracellular parasites, lack their own metabolic machinery; they hijack the host cell’s machinery for replication. Therefore, viruses do not possess the metabolic pathways or structures that antibiotics are designed to inhibit, rendering antibiotics ineffective against them.
– Antibiotics target bacterial processes, not viral ones.
– Viruses lack their own metabolic pathways for functions like replication, using host cell machinery instead.
– Taking antibiotics for viral infections is ineffective and contributes to antibiotic resistance in bacteria.
– Viral infections require antiviral medications, not antibiotics.
The misuse of antibiotics for viral infections is a major driver of antibiotic resistance, a growing global health crisis. Antiviral drugs work by targeting different stages of the viral life cycle, such as entry into the host cell, replication of viral genetic material, or assembly and release of new viruses. Examples of viral infections include the common cold, flu, COVID-19, measles, and HIV.

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14. Which one of the following statements regarding viruses is not true

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

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Viruses need living cells to reproduce.
All viruses are parasites.
Viruses can synthesize their food through photosynthesis.
Viruses are similar to chemical substances outside the host.
This question was previously asked in
UPSC NDA-2 – 2019
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The correct option is C) Viruses can synthesize their food through photosynthesis.
Viruses are acellular entities that lack the metabolic machinery necessary for processes like photosynthesis or self-synthesis of food. They are obligate intracellular parasites.
Viruses require a host cell to reproduce because they lack the necessary enzymes and ribosomes. They hijack the host cell’s machinery to replicate. Outside a host cell, a virus particle is essentially an inert complex of genetic material and protein, behaving like a chemical substance. They obtain energy and building blocks from the host cell, not through photosynthesis or any independent metabolic activity.

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15. It is difficult to kill viruses because they

It is difficult to kill viruses because they

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consist of tough protein coat
are very small in size
lack cellular structure
spend a lot of time inside the host's cells
This question was previously asked in
UPSC NDA-2 – 2016
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Viruses lack cellular structure and metabolic machinery of their own. They are obligate intracellular parasites, relying entirely on the host cell’s machinery for replication.
The absence of their own metabolic processes means that many common antimicrobial treatments, such as antibiotics which target bacterial cellular functions, are ineffective against viruses. Developing antiviral drugs is challenging because they must target viral processes without harming the host cell’s similar processes.
While having a protein coat (A) and small size (B) are characteristics of viruses, they don’t inherently make them difficult to kill compared to other microbes. Spending time inside host cells (D) makes them inaccessible to some therapies and antibodies, contributing to the difficulty in *treating* viral infections, but the fundamental reason for the difficulty in *killing* them selectively lies in their non-cellular nature and dependence on host processes.

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

AIDS is caused by a virus whose genetic material is

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single stranded circular DNA
double stranded DNA
single stranded RNA
double stranded RNA
This question was previously asked in
UPSC NDA-1 – 2018
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The correct answer is C) single stranded RNA.
AIDS (Acquired Immunodeficiency Syndrome) is caused by the Human Immunodeficiency Virus (HIV). HIV is a retrovirus, and retroviruses are characterized by having their genetic material in the form of RNA, specifically single-stranded RNA. This RNA is then converted into double-stranded DNA inside the host cell using an enzyme called reverse transcriptase, which is unique to retroviruses.
HIV has two copies of its single-stranded RNA genome. These RNA molecules are encapsidated along with enzymes like reverse transcriptase, integrase, and protease within the viral particle. This allows the virus to infect human cells and replicate its genetic material by incorporating a DNA copy into the host cell’s genome.

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17. Dengue virus causes high fever, rashes and reduces the number of a par

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

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Monocytes
Platelets
Eosinophils
Neutrophils
This question was previously asked in
UPSC NDA-1 – 2017
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Dengue fever is a mosquito-borne viral infection that can cause severe illness. One of the characteristic effects of dengue virus is its impact on blood cells, particularly platelets (thrombocytes). Dengue infection often leads to a significant decrease in platelet count (thrombocytopenia), which can increase the risk of bleeding.
Dengue virus significantly reduces the number of platelets in the blood.
While dengue can affect white blood cell counts (often causing a decrease in lymphocytes and neutrophils), the reduction in platelets is a hallmark of the disease and a critical factor in assessing the severity and managing potential complications like dengue hemorrhagic fever. Monocytes and eosinophils are types of white blood cells, and while their counts can fluctuate during infection, the primary clinically significant reduction targeted by the question is typically platelets.

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18. The recent outbreak of extremely contagious lumpy skin disease affects

The recent outbreak of extremely contagious lumpy skin disease affects mostly which one of the following animals?

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Cow
Dog
Pig
Horse
This question was previously asked in
UPSC Geoscientist – 2023
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The recent outbreak of extremely contagious lumpy skin disease affects mostly Cow (cattle).
– Lumpy Skin Disease (LSD) is a viral disease of cattle and water buffalo, caused by a virus of the genus Capripoxvirus.
– It is transmitted by insects and causes characteristic skin nodules (lumps), fever, reduced milk production, and can lead to death.
LSD does not typically affect dogs, pigs, or horses. The disease caused significant outbreaks in cattle populations across India and neighboring countries in 2022 and 2023, leading to substantial economic losses for farmers.

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19. Which one of the following statements is correct about a virus?

Which one of the following statements is correct about a virus?

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It is a free-living organism.
It contains nucleic acid and protein.
It can synthesize proteins.
It can generate its own energy.
This question was previously asked in
UPSC Geoscientist – 2022
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The correct statement about a virus is that it contains nucleic acid and protein.
Viruses are acellular entities composed primarily of genetic material (DNA or RNA) enclosed within a protein coat called a capsid. Some viruses also have an outer lipid envelope derived from the host cell membrane.
Viruses are obligate intracellular parasites, meaning they cannot replicate or carry out metabolic processes independently. They rely on the host cell’s machinery for protein synthesis, energy generation, and replication. Unlike free-living organisms, viruses cannot survive or reproduce outside of a host cell.

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20. Which one of the following statements explains higher mutation rate an

Which one of the following statements explains higher mutation rate and faster evolution found in RNA virus?

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RNA is relatively unstable compared to DNA.
Virus can multiply only within the living cell of a host.
Metabolic processes are absent in virus.
Virus can remain latent for a long period.
This question was previously asked in
UPSC CDS-2 – 2018
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The correct answer is A) RNA is relatively unstable compared to DNA.
RNA molecules are generally less stable than DNA molecules primarily because of the presence of a hydroxyl group at the 2′ carbon of the ribose sugar, which makes the phosphodiester bond more susceptible to hydrolysis. Additionally, RNA viruses typically lack the proofreading mechanisms that DNA polymerases have, leading to a much higher error rate during replication. These factors result in a higher mutation rate.
Higher mutation rates in RNA viruses contribute to faster evolution, allowing them to adapt quickly to changing environments, evade host immune responses, and develop resistance to antiviral drugs. Options B, C, and D describe general characteristics of viruses but do not specifically explain the higher mutation rate or faster evolution relative to DNA viruses or other life forms.

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