Prelims Previous Year Questions

1)        Which of the following diseases can be transmitted from one person to another through tattooing? (2013)

1. Chikungunya
2. Hepatitis B
3. HIV-AIDS

            Select the correct answer using the codes given below,

(a)      1 only

(b)      2 and 3 only

(c)       1 and 3 only

(d)      1, 2 and 3

Answer: B

Explanation:

• Tattooing can potentially transmit infectious diseases if proper hygiene and safety measures are not followed.
• Chikungunya: Chikungunya is primarily transmitted to people through the bite of infected mosquitoes. It is not directly transmitted through tattooing.
• Hepatitis B: Hepatitis B is a viral infection that can be transmitted through the exchange of bodily fluids, including blood. If the equipment used for tattooing is not properly sterilized, it can lead to the transmission of hepatitis B, as the virus can be present in blood.
• HIV-AIDS: Similar to hepatitis B, HIV (Human Immunodeficiency Virus) can be transmitted through the exchange of certain bodily fluids, including blood. If the tattooing equipment is contaminated with infected blood and is not adequately sterilized, there is a risk of transmitting HIV.

2)        Which of the following statements is/are correct? (2013)

1. Viruses lack enzymes necessary for the generation of energy.
2. Viruses can be cultured in any synthetic medium.
3. Viruses are transmitted from one organism to another by biological vectors only.

            Select the correct answer using the codes given below.

(a)      1 only

(b)      2 and 3 only

(c)       1 and 3 only

(d)      1, 2 and 3

Answer: A

Explanation:

Viruses lack enzymes necessary for the generation of energy.

• This statement is correct. Viruses are considered obligate intracellular parasites, meaning they cannot generate energy on their own. They lack the cellular machinery, including enzymes, for metabolic processes like energy generation. Instead, they rely on the host cell’s machinery to replicate and produce energy.

Viruses can be cultured in any synthetic medium.

• This statement is incorrect. Unlike bacteria and other microorganisms, viruses cannot be cultured in any synthetic medium. They require a living host cell to replicate. In laboratory settings, scientists use host cells (such as animal cells or bacterial cells) to culture viruses.

Viruses are transmitted from one organism to another by biological vectors only.

• This statement is incorrect. Viruses can be transmitted through various means, not limited to biological vectors. While some viruses are indeed transmitted by biological vectors (organisms that can transmit the virus from one host to another, like mosquitoes for certain diseases), others can be transmitted through direct contact, contaminated surfaces, or through the air.

3)        Consider the following diseases: (2014)

1. Diphtheria
2. Chickenpox
3. Smallpox

            Which of the above diseases has/have been eradicated in India?

(a)      1 only

(b)      3 only

(c)       1, 2 and 3

(d)      None

Answer: B

Explanation:

• Diphtheria: Diphtheria has not been eradicated in India. It is a bacterial infection caused by Corynebacterium diphtheriae. Vaccination programs have significantly reduced the incidence of diphtheria, but it is not eradicated.
• Chickenpox: Chickenpox has not been eradicated in India. It is a viral infection caused by the varicella-zoster virus. Vaccination is available for chickenpox, but the disease has not been eliminated.
• Smallpox: Smallpox has been eradicated globally, including in India. The World Health Organization (WHO) officially declared the eradication of smallpox in 1980. Smallpox is the only human disease to be eradicated through vaccination efforts.
• Smallpox was eradicated from India in 1977

4)        Consider the following pairs (2014)

 Which of the pairs given above is/are correctly matched?

(a)      1 and 2 only

(b)      3 only

(c)       1, 2 and 3

(d)      None

Answer: A

Explanation:

Vitamin C – Scurvy:

• Deficiency Disease: Scurvy is a disease caused by a deficiency of vitamin C. Vitamin C is essential for the synthesis of collagen, a protein that helps in the formation of connective tissues in the body.

Vitamin D – Rickets:

• Deficiency Disease: Rickets is a condition that results from a deficiency of vitamin D, calcium, or phosphate. Vitamin D is crucial for the proper absorption of calcium and phosphate, and its deficiency can lead to weak or soft bones.

Vitamin A – Night Blindness:

• Deficiency Disease: Night Blindness is associated with a deficiency of vitamin A. Vitamin A is essential for maintaining healthy skin and mucous membranes, and it is also important for vision, particularly in low-light conditions.

5)        H1N1 virus is sometimes mentioned in the news with reference to which one of the following diseases. (2015)

(a)       AIDS

(b)      Bird flu

(c)       Dengue

(d)      Swine flu

Answer: D

Explanation:

• H1N1, commonly known as swine flu, is a subtype of influenza A virus that causes respiratory illness in humans. The “H1N1” designation refers to the specific types of proteins found on the surface of the virus, namely hemagglutinin (H) and neuraminidase (N). Swine flu got its name because it was originally identified in pigs.
• In 2009, there was a global outbreak of H1N1 influenza, leading to widespread illness and concern. The virus spread easily from person to person, and it caused symptoms similar to those of seasonal influenza, including fever, cough, sore throat, body aches, and fatigue. The World Health Organization (WHO) declared it a pandemic, but it was later determined that the severity of the illness was similar to that of seasonal flu.
• Since then, H1N1 has continued to circulate as one of the seasonal influenza viruses. It is included in the annual flu vaccine to provide protection against this specific strain. While H1N1 is not as prominent in the news as it was during the 2009 pandemic, it remains a part of the seasonal flu viruses that health authorities monitor and vaccinate against.

6)        Which of the following statements is/are correct? (2016)

            Viruses can infect

1. bacteria
2. fungi
3. plants

            Select the correct answer using the code given below.

(a)      1 and 2 only

(b)      3 only

(c)       1 and 3 only

(d)      1, 2 and 3

Answer: D

Explanation:

• Viruses can infect bacteria: This is correct, and viruses that infect bacteria are known as bacteriophages. They are specific to bacterial hosts and play a crucial role in controlling bacterial populations in various environments.
• Viruses can infect fungi: This is also correct. There are viruses, known as mycoviruses, that infect fungi. These viruses can affect the growth, development, and virulence of fungal hosts.
• Viruses can infect plants: This is correct as well. Plant viruses are a significant concern in agriculture as they can cause diseases in crops, affecting crop yield and quality. Examples include the Tobacco Mosaic Virus (TMV) and the Tomato Yellow Leaf Curl Virus.

7)        Consider the following statements: (2017)

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?

(a)      1 only

(b)      2 only

(c)       Both 1 and 2

(d)      Neither 1 nor 2

Answer: C

Explanation:

• In tropical regions, Zika virus disease is transmitted by the same mosquito that transmits dengue: This is true. The primary vector for Zika virus transmission is the Aedes mosquito, particularly Aedes aegypti. This mosquito species is also responsible for the transmission of other viruses like dengue and chikungunya.
• Sexual transmission of Zika virus disease is possible: This statement is correct. Zika virus can be sexually transmitted from an infected person to their partner. This mode of transmission became a significant concern during the Zika virus outbreak.

8)        Which of the following are the reasons for the occurrence of multi-drug resistance in microbial pathogens in India? (2019)

1. Genetic predisposition of some people
2. Taking incorrect doses antibiotics to cure diseases
3. Using antibiotics in livestock farming
4. Multiple chronic diseases in some people

Select the correct answer using the code given below.

(a)       1 and 2

(b)      2 and 3 only

(c)       1, 3 and 4

(d)      2, 3 and 4

Answer: B

Explanation:

• Genetic predisposition of some people: While genetic factors can play a role in individual responses to drugs, they are not a direct cause of multi-drug resistance in microbial pathogens.
• Taking incorrect doses of antibiotics to cure diseases: Incorrect use of antibiotics, including incorrect doses, is a major factor contributing to the development of drug resistance in microbial pathogens. This includes factors such as not completing the prescribed course of antibiotics.
• Using antibiotics in livestock farming: The use of antibiotics in livestock farming, often for promoting growth or preventing diseases, is a significant contributor to the development of drug resistance. The widespread use of antibiotics in agriculture can lead to the emergence of resistant strains of bacteria.
• Multiple chronic diseases in some people: While individuals with chronic diseases may be more susceptible to infections, the occurrence of multiple chronic diseases itself is not a direct cause of multi-drug resistance in microbial pathogens.

9)        Which one of the following statements is not correct? (2019)

(a)      Hepatitis B virus is transmitted Much like HIV.

(b)      Hepatitis B, unlike Hepatitis C, does not have a vaccine.

(c)       Globally, the number of people infected with Hepatitis B and C viruses are several times more than those infected with HIV.

(d)      Some of those of those infected with Hepatitis B and C viruses do not show the symptoms for many years.

Answer: B

Explanation:

(a)      Hepatitis B virus is transmitted much like HIV: This statement is correct. Both Hepatitis B and HIV can be transmitted through contact with infected blood, unprotected sex, and from an infected mother to her child during childbirth.

(b)      Hepatitis B, unlike Hepatitis C, does not have a vaccine: This statement is not correct. There is an effective vaccine for Hepatitis B. The Hepatitis B vaccine has been available since the early 1980s and is a crucial tool in preventing Hepatitis B infections.

(c)      Globally, the number of people infected with Hepatitis B and C viruses is several times more than those infected with HIV: This statement is correct. Hepatitis B and C infections are more widespread globally compared to HIV infections.

(d)      Some of those infected with Hepatitis B and C viruses do not show symptoms for many years: This statement is correct. Many individuals infected with Hepatitis B or C may not show symptoms immediately, and the infections can progress without noticeable signs for an extended period. This is one of the reasons these infections can lead to complications if not detected and treated early. 

10)     What is the importance of using Pneumococcal Conjugate Vaccines in India? (2020)

1. These vaccines are effective against pneumonia as well as meningitis and sepsis.
2. Dependence on antibiotics that are not effective against drug-resistant bacteria can be reduced.
3. These vaccines have no side effects and cause no allergic reactions.

Select the correct answer using the code given below:

(a)       1 only

(b)      1 and 2 only

(c)       3 only

(d)      1, 2 and 3

Answer: B

Explanation:

• These vaccines are effective against pneumonia as well as meningitis and sepsis: This statement is correct. Pneumococcal Conjugate Vaccines (PCVs) are designed to protect against diseases caused by the bacterium Streptococcus pneumoniae. These diseases include pneumonia, meningitis, and sepsis.
• Dependence on antibiotics that are not effective against drug-resistant bacteria can be reduced: This statement is correct. Vaccination with PCVs helps prevent infections caused by Streptococcus pneumoniae, which is a major contributor to pneumonia. By preventing these infections, the need for antibiotic treatment and the risk of antibiotic resistance can be reduced.
• These vaccines have no side effects and cause no allergic reactions: This statement is not correct. While vaccines, including PCVs, are generally safe and well-tolerated, they can have side effects. Common side effects may include mild reactions at the injection site or mild fever. Severe allergic reactions are extremely rare but not impossible.

11)     With reference to recent developments regarding Recombinant Vector Vaccines’, consider the following statements: (2021)

1. Genetic engineering is applied in the development of these vaccines.
2. Bacteria and viruses are used as vectors.

            Which of the statements given above is/are correct?

(a)       1 only

(b)      2 only

(c)       Both 1 and 2

(d)      Neither 1 nor 2

Answer: C

Explanation:

• Genetic engineering is applied in the development of these vaccines: This statement is correct. Recombinant Vector Vaccines involve the use of genetic engineering techniques to insert genetic material (usually a gene that codes for a part of the pathogen) into a different, harmless vector. This vector then acts as a vehicle to deliver the genetic material into the cells of the host, triggering an immune response.
• Bacteria and viruses are used as vectors: This statement is correct. Recombinant vectors can include both bacteria and viruses. In the context of vaccines, these vectors are modified to carry genetic material that stimulates an immune response without causing the disease. Common vectors include adenoviruses and modified vaccinia virus Ankara (MVA).

12)     In the context of hereditary diseases, consider the following statements: (2021)

1. Passing on mitochondrial diseases from parent to child can be prevented by mitochondrial replacement therapy either before or after in vitro fertilization of egg.
2. A child inherits mitochondrial diseases entirely from mother and not from father.

Which of the statements given above is/are correct?

(a)       1 only

(b)      2 only

(c)       Both 1 and 2

(d)      Neither 1 nor 2

Answer: C

Explanation:

• Passing on mitochondrial diseases from parent to child can be prevented by mitochondrial replacement therapy either before or after in vitro fertilization of the egg: This statement is correct. Mitochondrial replacement therapy (MRT) is a technique that involves replacing defective mitochondria in the egg or embryo with healthy mitochondria from a donor. This can be done either before or after in vitro fertilization to prevent the transmission of mitochondrial diseases from the mother to the child.
• A child inherits mitochondrial diseases entirely from the mother and not from the father: This statement is correct. Mitochondria are inherited maternally, meaning that the mitochondrial DNA (mtDNA) is passed down from the mother to her offspring. The father does not contribute mitochondria to the offspring. As a result, mitochondrial diseases, which are caused by mutations in the mtDNA, are inherited exclusively from the mother.

13)     Consider the following: (2021)

1. Bacteria
2. Fungi
3. Virus.

            Which of the above can be cultured in artificial/synthetic medium?

(a)      1 and 2 only

(b)      2 and 3 only

(c)       1 and 3 only

(d)      1, 2 and 3

Answer: A

Explanation:

• Bacteria: Bacteria can be cultured in artificial/synthetic medium. In laboratory settings, scientists use artificial media that provide all the nutrients required for bacterial growth.
• Fungi: Fungi can also be cultured in artificial/synthetic medium. Similar to bacteria, fungi can be grown in laboratory media that contain the necessary nutrients for their growth.
• Virus: Viruses cannot be cultured on artificial/synthetic media alone because they lack the cellular machinery for metabolic processes and replication. However, they can be cultured using living host cells in a laboratory setting. The host cells provide the necessary environment for the virus to replicate.

14)     Consider the following statements: (2021)

1. Adenoviruses have single-stranded DNA genomes whereas retroviruses have double-stranded DNA genomes.
2. Common cold is sometime caused by an adenovirus whereas AIDS is caused by a retrovirus.

Which of the statements given above is/are correct?

(a)       only

(b)      2 only

(c)       Both 1 and 2

(d)      Neither 1 nor 2

Answer: B

Explanation:

• Adenoviruses: Adenoviruses actually have double-stranded DNA genomes, not single-stranded DNA genomes.
• Common cold and AIDS: Adenoviruses can indeed cause the common cold, but they are not responsible for AIDS. AIDS is caused by the human immunodeficiency virus (HIV), which is a retrovirus.

15)     The term ‘ACE2’ is talked about in the context of (2021)

(a)      genes introduced in the genetically modified plants

(b)      development of India’s own satellite navigation system

(c)       radio collars for wildlife tracking

(d)      spread of viral diseases

Answer: D

Explanation:

• ACE2 stands for Angiotensin-Converting Enzyme 2. It is a protein on the surface of many cell types. It serves as the entry point into cells for some coronaviruses, including the SARS-CoV-2 virus responsible for the COVID-19 pandemic. The interaction between the spike protein of the virus and ACE2 is a crucial step in the viral infection process. Understanding ACE2 and its role is significant in the context of studying and combating viral diseases, particularly those caused by coronaviruses. 

16)     In the context of vaccines manufactured to prevent COVID-19 pandemic, consider the following statements: (2022)

1. The Serum Institute of India produced COVID-19 vaccine named Covishield using mRNA platform.
2. Sputnik V vaccine is manufactured using vector-based platform.
3. COVAXIN is an inactivated pathogen-based vaccine.

Which of the statements given above are correct?

(a)      1 and 2 only

(b)      2 and 3 only

(c)       1 and 3 only

(d)      1, 2 and 3

Answer: B

Explanation:

• The Serum Institute of India produced the COVID-19 vaccine named Covishield, but it is not based on the mRNA platform. Covishield is an adenovirus vector-based vaccine.
• Sputnik V vaccine is indeed manufactured using a vector-based platform.
• COVAXIN is an inactivated pathogen-based vaccine. 

17)     Which one of the following statements best describes the role of B cells and T cells in the human body? (2022)

(a)      They protect the body from environmental allergens.

(b)      They alleviate the body’s pain and inflammation.

(c)       They act as immunosuppressants in the body.

(d)      They protect the body from the diseases caused by pathogens.

Answer: D

Explanation:

• B cells and T cells are two key types of lymphocytes, a type of white blood cell, that play crucial roles in the immune system’s defense against diseases caused by pathogens.

B Cells (B Lymphocytes):

• Role: B cells are primarily responsible for the production of antibodies, which are proteins that recognize and neutralize specific pathogens such as bacteria and viruses.
• Process: When a pathogen enters the body, B cells recognize its unique antigens (molecules on the surface of the pathogen) and, upon activation, transform into plasma cells. Plasma cells then produce antibodies that can bind to and mark the pathogen for destruction by other immune cells.

T Cells (T Lymphocytes):

• Role: T cells have diverse functions, including directly attacking infected cells and coordinating immune responses. There are two main types: helper T cells and cytotoxic T cells.
• Helper T Cells (Th): Assist other immune cells, including B cells, by releasing signaling molecules (cytokines) that regulate and enhance immune responses.
• Cytotoxic T Cells (Tc): Destroy infected or abnormal cells directly by inducing apoptosis (programmed cell death).