UPSC-CMS 2009 Practice Questions

Q: Which of the following correctly describes gene therapy ?

Introduction of gene sequence into a cell. ***Introduction of gene sequence into a cell*** - **Gene therapy** fundamentally involves the **delivery of genetic material** (DNA or RNA) into a patient's cells to treat or prevent disease. - The goal is to correct a **genetic defect**, provide a new therapeutic function, or alter gene expression for a desired outcome. *Mapping and isolation of gene sequence* - While essential steps in understanding and preparing for gene therapy, **mapping and isolation** alone do not constitute the therapy itself. - These processes are preliminary research activities to identify the target gene and its location. *Synthesis of DNA probes with specific sequence* - **DNA probes** are short, single-stranded DNA or RNA sequences used to detect the presence of complementary nucleic acid sequences. - Their synthesis is a technique used in **molecular diagnostics** and research, not gene therapy, which aims to introduce functional genes. *Use of polymerase chain reaction technique* - **PCR** is a molecular biology technique used to amplify a specific segment of DNA, creating many copies. - It is a tool for **diagnosis**, research, and sometimes in the preparation of genetic material for therapy, but it is not gene therapy itself.

Q: The law stating that "the relative frequencies of each gene allele tend to remain constant from generation to generation" is known as

Hardy-Weinberg Law. ***Hardy-Weinberg Law*** - The **Hardy-Weinberg principle** states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences. - This law provides a baseline for understanding how populations evolve by identifying the conditions under which evolution *does not* occur. *Lamarck's Law* - **Lamarck's theory of inheritance of acquired characteristics** suggested that traits acquired during an organism's lifetime could be passed on to offspring. - This concept is largely disproven and not relevant to allele frequency constancy across generations. *David-Morgan's Law* - This is not a recognized law in genetics. There was a prominent geneticist named **Thomas Hunt Morgan**, whose work focused on fruit flies and established the **chromosome theory of inheritance** and concepts like linkage and crossing over. - While significant to genetics, his work does not describe the constancy of allele frequencies in a population. *Mendel's Law* - **Mendel's Laws of Inheritance** (segregation and independent assortment) describe how traits are passed from parents to offspring through the inheritance of discrete units (genes). - While fundamental to explaining inheritance, they do not directly state that allele frequencies remain constant in a population across generations under specific conditions, as the Hardy-Weinberg law does.

Q: Consider the following : 1. Land filling for source reduction. 2. Vaccination of pigs in the risk area. 3. Immunization of children in risk area. Which of the above are the recommended control strategies for Japanese Encephalitis ?

2 and 3 only. ***2 and 3 only*** - **Immunization of children** in risk areas is the **primary recommended control strategy** for Japanese Encephalitis, as children are particularly vulnerable to severe encephalitis and long-term neurological sequelae from JEV infection. Human vaccination is endorsed by WHO and forms the backbone of JE control programs. - **Vaccination of pigs**: While pigs act as **amplifying hosts** for JEV, **pig vaccination is NOT routinely recommended** by WHO or most national programs due to practical challenges (high turnover of pig populations, cost-effectiveness issues). However, some older guidelines and regional programs have included this as a supplementary strategy in specific contexts. *1 only* - **Landfilling for source reduction** is a method for **solid waste disposal** and is NOT a recommended strategy for Japanese Encephalitis control. - JE vectors (**Culex tritaeniorhynchus mosquitoes**) breed primarily in **rice paddies, irrigation channels, and stagnant water bodies**, not in areas affected by solid waste. - Appropriate environmental management would focus on **water management** in agricultural areas, not landfilling. *1, 2 and 3* - This option incorrectly includes **landfilling**, which is not a recognized JE control strategy. - Landfilling does not target the breeding sites of Culex mosquitoes that transmit JE. *1 and 2 only* - This option incorrectly includes **landfilling** and critically omits **human immunization**, which is the most important and universally recommended control measure. - Human vaccination provides direct protection and is the cornerstone of JE prevention in endemic areas.

Q: In a community with one lakh population, 20,000 slides were examined in a particular year. Out of these 100 were positive for malarial parasite. What is the Annual Parasite Incidence (API) in this community ?

1. ***Correct Answer: 1*** The **Annual Parasite Incidence (API)** is a key epidemiological indicator for malaria surveillance, defined as the number of **confirmed positive malaria cases per 1,000 population per year**. **Formula:** API = (Number of positive cases / Total population) × 1,000 **Calculation:** - Population = 1,00,000 (one lakh) - Positive cases = 100 - API = (100 / 1,00,000) × 1,000 = **1** The number of slides examined (20,000) is relevant for calculating the **Slide Positivity Rate (SPR)** but not directly used in the API calculation. *Incorrect: 2* - This would be correct if there were 200 positive cases in the same population - Represents double the actual API *Incorrect: 0.5* - This would be correct if there were only 50 positive cases in the population - Represents half the actual API *Incorrect: 5* - This would result from incorrectly using the number of slides examined (20,000) as the denominator instead of the total population (1,00,000) - Confuses SPR calculation methodology with API calculation

Q: Amniocentesis in early pregnancy for genetic disorders is a kind of

primary prevention. ***primary prevention*** - **Primary prevention** aims to *prevent disease from occurring* in the first place by reducing exposure to risk factors and preventing the birth of affected individuals - Amniocentesis in early pregnancy is a **prenatal diagnostic test** that detects genetic disorders in the fetus (who is at risk but not yet diseased) - The goal is to *prevent the occurrence* of genetic disease in the population by enabling informed reproductive decisions and preventing the birth of severely affected infants - This is classified as primary prevention because it **prevents the disease from manifesting** in the community *secondary prevention* - **Secondary prevention** focuses on *early detection and treatment* of disease in individuals who are already affected but asymptomatic - Examples include cancer screening (mammography, Pap smear), hypertension screening, and diabetes screening in adults - Amniocentesis is NOT secondary prevention because the fetus is not yet "diseased" – testing occurs before disease manifestation to prevent it *tertiary prevention* - **Tertiary prevention** aims to *reduce complications* and disability from established, symptomatic disease - Focuses on rehabilitation, preventing progression, and improving quality of life after disease has occurred - Examples include physiotherapy after stroke, insulin therapy for diabetes, and cardiac rehabilitation *primordial prevention* - **Primordial prevention** addresses *underlying determinants* of disease by preventing risk factors from developing in the population - Involves broad public health policies, environmental modifications, and socioeconomic interventions - Examples include tobacco control policies, promoting healthy urban design, and reducing environmental pollution

Q: Which one of the following is a correct combination regarding Indian population?

Blood group O 40%; Rh negative 7%. ***Blood group O 40%; Rh negative 7%*** - In the Indian population, **Blood group O** is indeed the most common, accounting for approximately **30-40%** of the population. - The prevalence of **Rh-negative** individuals in India is relatively low, typically around **5-7%**, making this combination accurate. *Blood group AB 20%; Rh negative 15%* - **Blood group AB** is the least common blood group, typically less than **10%** in the Indian population, making 20% an overestimation. - **Rh negative** prevalence of 15% is significantly higher than the reported figures for India, which are usually around 5-7%. *Blood group A 40%; Rh positive 80%* - While **Blood group A** is common, 40% might be slightly higher than some estimates, which often place it closer to 20-25%. - **Rh positive** prevalence in India is much higher than 80%, typically around **93-95%**, making 80% an underestimation. *Blood group B 33%; Rh positive 99%* - **Blood group B** is also very common in India, often around 30-35%, so 33% is a reasonable estimate. - However, **Rh positive** prevalence of 99% is an overestimation; the actual prevalence is closer to **93-95%**.

Q: Consider the following : 1. Right to be informed 2. Right to choose 3. Right to seek redressal Which of the above is/are the rights included in the Consumer Protection Act ?

1, 2 and 3. ***1, 2 and 3*** - The **Consumer Protection Act (CPA)** grants consumers several fundamental rights to ensure fair treatment in the marketplace. - These rights include the right to **be informed** about the quality, quantity, potency, purity, standard, and price of goods or services, the right to **choose** from a variety of goods and services at competitive prices, and the right to **seek redressal** against unfair trade practices or exploitation. *1 only* - While the **right to be informed** is a crucial aspect of consumer protection, it is not the sole right provided under the Consumer Protection Act. - The Act encompasses a broader set of rights designed to empower consumers. *2 and 3 only* - The **right to choose** and the **right to seek redressal** are indeed part of the Consumer Protection Act. - However, this option omits the equally important **right to be informed**, which is a foundational element of consumer protection. *1 and 2 only* - The **right to be informed** and the **right to choose** are significant consumer rights. - This option, however, overlooks the **right to seek redressal**, which is vital for consumers to obtain justice against unfair practices.

Q: With reference to lepromin test, which one of the following statements is correct?

Lepromin test is strongly positive in tuberculoid leprosy. ***Lepromin test is strongly positive in tuberculoid leprosy*** - In **tuberculoid leprosy**, the immune system mounts a strong cell-mediated response against *Mycobacterium leprae*, leading to a strongly positive lepromin reaction. - A positive lepromin test indicates a good host immune response and is associated with the **paucibacillary** forms of the disease. *It can be used as a diagnostic test* - The lepromin test is not a diagnostic tool for leprosy; it primarily assesses the host's **cell-mediated immunity** to *Mycobacterium leprae* antigens. - Diagnosis of leprosy relies on **clinical signs**, **skin smears** for acid-fast bacilli, and histopathological examination, not the lepromin test. *Its interpretation is done within 24 hours* - The lepromin test interpretation involves two phases: the **Fernandez reaction** (early reaction at 24-48 hours) and the **Mitsuda reaction** (late reaction at 3-4 weeks). - The most significant and commonly referred result, the **Mitsuda reaction**, is read at **3 to 4 weeks** after injection. *It is not affected by BCG vaccine* - The **BCG vaccine**, which is used to prevent tuberculosis, can induce some cross-reactivity and lead to a positive lepromin test in individuals who have received it. - This cross-reactivity can sometimes confound the interpretation of the lepromin test, as both mycobacteria share common antigens.

Q: The period of time required for the development of the parasite from the gametocyte to sporozoite stage in the body of the mosquito is about 10-20 days. This period is also referred to as

Extrinsic incubation period. ***Extrinsic incubation period*** - This term refers to the time taken for the **Plasmodium parasite** to develop from the **ingested gametocytes** to the **infective sporozoites** within the mosquito vector. - The duration of this period is typically 10-20 days, depending on the **species of Plasmodium** and environmental factors such as temperature. *Asexual cycle* - The asexual cycle, or **schizogony**, occurs within the human host, specifically in the **liver** (exoerythrocytic) and **red blood cells** (erythrocytic). - This cycle involves the multiplication of the parasite and is responsible for the clinical symptoms of malaria. *Schizogony* - **Schizogony** is a form of asexual reproduction characteristic of **apicomplexan parasites**, including Plasmodium. - It describes the process where a single parasitic cell (e.g., a **merozoite** or **sporozoite**) divides multiple times within a host cell to produce many daughter cells. *Erythrocytic cycle* - The **erythrocytic cycle** is a specific part of the human asexual cycle where **merozoites** infect red blood cells, multiply, and then lyse the cells to release more merozoites. - This cycle is responsible for the periodic fevers and other symptoms of malaria, but does not involve development within the mosquito.

Q: Which one of the following is a characteristic of Human Immunodeficiency Virus (HIV)?

It is easily killed by heat. ***It is easily killed by heat*** - HIV is an **enveloped RNA virus** that is highly susceptible to inactivation by heat, typically at **56-60°C for 30 minutes**. - This characteristic is important for **sterilization of medical equipment** and understanding the environmental stability of the virus. - Heat lability is a key feature of enveloped viruses due to disruption of the lipid envelope. *It is easily killed by T4 lymphocytes* - **CD4+ T lymphocytes (T4 cells)** are the primary **target cells** for HIV, meaning the virus infects and ultimately destroys them. - HIV evades the immune system and **replicates within** these cells, leading to progressive immunodeficiency. - The virus is NOT killed by T4 cells; rather, it uses them for replication and destroys them in the process. *It cannot cross blood brain barrier* - HIV is known to **cross the blood-brain barrier (BBB)** early in infection, leading to neurological complications. - Presence of HIV in the central nervous system contributes to conditions like **HIV-associated neurocognitive disorder (HAND)** and HIV encephalopathy. - Infected macrophages and monocytes serve as "Trojan horses" carrying the virus across the BBB. *It is resistant to acetone* - HIV is an **enveloped virus**, and its lipid envelope is **susceptible to dissolution by lipid solvents** such as acetone, alcohol, and detergents. - This property makes HIV vulnerable to inactivation by common disinfectants and explains its poor environmental stability. - The envelope is essential for viral entry, so its disruption renders the virus non-infectious.

Question 1

Which of the following correctly describes gene therapy ?

Accepted Answer

Introduction of gene sequence into a cell

Answer

Mapping and isolation of gene sequence

Answer

Synthesis of DNA probes with specific sequence

Answer

Use of polymerase chain reaction technique

Question 2

The law stating that "the relative frequencies of each gene allele tend to remain constant from generation to generation" is known as

Accepted Answer

Hardy-Weinberg Law

Answer

Lamarck's Law

Answer

David-Morgan's Law

Answer

Mendel's Law

Question 3

Consider the following :

1. Land filling for source reduction.
2. Vaccination of pigs in the risk area.
3. Immunization of children in risk area. Which of the above are the recommended control strategies for Japanese Encephalitis ?

Accepted Answer

2 and 3 only

Answer

1 only

Answer

1, 2 and 3

Answer

1 and 2 only

Question 4

In a community with one lakh population, 20,000 slides were examined in a particular year. Out of these 100 were positive for malarial parasite. What is the Annual Parasite Incidence (API) in this community ?

Accepted Answer

1

Answer

2

Answer

0.5

Answer

5

Question 5

Amniocentesis in early pregnancy for genetic disorders is a kind of

Accepted Answer

primary prevention

Answer

secondary prevention

Answer

tertiary prevention

Answer

primordial prevention

Question 6

Which one of the following is a correct combination regarding Indian population?

Accepted Answer

Blood group O 40%; Rh negative 7%

Answer

Blood group AB 20%; Rh negative 15%

Answer

Blood group A 40%; Rh positive 80%

Answer

Blood group B 33%; Rh positive 99%

Question 7

Consider the following :

1. Right to be informed
2. Right to choose
3. Right to seek redressal Which of the above is/are the rights included in the Consumer Protection Act ?

Accepted Answer

1, 2 and 3

Answer

1 only

Answer

2 and 3 only

Answer

1 and 2 only

Question 8

With reference to lepromin test, which one of the following statements is correct?

Accepted Answer

Lepromin test is strongly positive in tuberculoid leprosy

Answer

It can be used as a diagnostic test

Answer

Its interpretation is done within 24 hours

Answer

It is not affected by BCG vaccine

Question 9

The period of time required for the development of the parasite from the gametocyte to sporozoite stage in the body of the mosquito is about 10-20 days. This period is also referred to as

Accepted Answer

Extrinsic incubation period

Answer

Asexual cycle

Answer

Schizogony

Answer

Erythrocytic cycle

Question 10

Which one of the following is a characteristic of Human Immunodeficiency Virus (HIV)?

Accepted Answer

It is easily killed by heat

Answer

It is easily killed by T4 lymphocytes

Answer

It cannot cross blood brain barrier

Answer

It is resistant to acetone

UPSC-CMS 2009

Biochemistry

Community Medicine

Dermatology

Microbiology