UPSC-CMS 2009 - Community Medicine PYQs Practice Questions

Q: Match the diseases in List-I with their respective incubation periods in List-II and select the correct answer using the code given below:

A→1 B→2 C→3 D→4. ***A→1 B→2 C→3 D→4*** - This option correctly matches **Measles (A)** with **10-14 days (1)**, which is the accurate incubation period for this **paramyxovirus infection**. - It properly pairs **Diphtheria (B)** with **2-6 days (2)**, reflecting the typical incubation period for **Corynebacterium diphtheriae**. - **Hepatitis A (C)** is correctly matched with **15-50 days (3)**, consistent with the incubation period of this **hepatotropic picornavirus**. - **Hepatitis B (D)** is correctly matched with **6 weeks-6 months (4)**, reflecting the prolonged incubation period of this **hepadnavirus**. *A→3 B→4 C→2 D→1* - This option incorrectly assigns **Measles** to **15-50 days**, which is far too long for this **viral exanthem** that typically manifests within **10-14 days**. - It also mismatches **Diphtheria** with **6 weeks-6 months**, when this **bacterial infection** has a much shorter incubation period of **2-6 days**. *A→4 B→3 C→2 D→1* - This option incorrectly assigns **Measles** to **6 weeks-6 months**, which is excessively long for this **acute viral infection**. - It also misplaces **Hepatitis A** to **2-6 days**, when its actual incubation period is much longer at **15-50 days**. *A→1 B→4 C→3 D→2* - This option correctly matches **Measles** with **10-14 days** but incorrectly assigns **Diphtheria** to **6 weeks-6 months** instead of the correct **2-6 days**. - It also mismatches **Hepatitis B** to **2-6 days**, when it actually has a much longer incubation period of **6 weeks-6 months**. [Practice more Community Medicine PYQs on OnCourse]

Q: For a screening test, 90% specificity means that 90% of non-diseased persons will give a

True negative result. ***True negative result*** - **Specificity** is defined as the proportion of **true negatives** among individuals **without the disease**. - A 90% specificity means that 90% of healthy individuals will correctly test negative for the disease. *False negative result* - A **false negative** occurs when a diseased person tests negative, which is related to the concept of **sensitivity**, not specificity. - This would imply missing actual cases of the disease. *True positive result* - A **true positive** occurs when a diseased person tests positive, which is also related to **sensitivity**. - This indicates accurate detection of the disease in affected individuals. *False positive result* - A **false positive** occurs when a non-diseased person inappropriately tests positive. - If 90% of non-diseased persons give a negative result (true negative), then 10% would give a **false positive result**. [Practice more Community Medicine PYQs on OnCourse]

Q: Berksonian bias is a selection bias which occurs in

Hospital based studies. ***Hospital based studies*** - **Berksonian bias** is a type of **selection bias** that occurs when the study population is drawn from a hospital or clinical setting. - This can lead to an artificially inflated or deflated association between risk factors and diseases, as hospital patients often have multiple health conditions or risk factors not representative of the general population. *Natural exposure studies* - These studies observe populations exposed to a factor naturally, without intervention, and are less prone to selection bias related to hospital admission. - While other biases can occur, **Berksonian bias** specifically relates to admission criteria for healthcare facilities. *Community based studies* - **Community-based studies** aim to recruit participants from the general population, making them less susceptible to **Berksonian bias** compared to hospital-based studies. - They strive for a more representative sample, reducing the selection pressures seen in clinical settings. *Laboratory based studies* - **Laboratory studies** typically use controlled environments and experimental designs, often involving cell cultures or animal models. - They are generally not subject to **Berksonian bias**, which is specific to human population studies drawing from clinical settings. [Practice more Community Medicine PYQs on OnCourse]

Q: Among the following, which has the highest quantity of retinol (Vitamin A) activity per 100 g of fruit?

Ripe Mango. ***Ripe Mango*** - **Ripe mangoes** are an excellent source of **beta-carotene**, which the body converts into **retinol (Vitamin A)**. - They contain approximately **1,262 µg retinol activity equivalents (RAE)** per 100 g, which is significantly higher than the other options listed. - While fruits contain provitamin A carotenoids rather than preformed retinol, mangoes provide the highest **Vitamin A activity** among these choices. *Papaya* - While papaya does contain **beta-carotene**, its concentration is much lower (approximately **47 µg RAE/100 g**). - It is a good source of Vitamin C and other antioxidants, but not the leading source of Vitamin A among these fruits. *Tomato* - Tomatoes are rich in **lycopene**, another carotenoid, but it is not converted to **retinol** as beta-carotene is. - They have low overall **Vitamin A activity** (approximately **42 µg RAE/100 g**) compared to mangoes. *Orange* - Oranges are primarily known for their high content of **Vitamin C** and are poor sources of **Vitamin A**. - Their Vitamin A activity is minimal (approximately **11 µg RAE/100 g**), with primary carotenoids being **beta-cryptoxanthin** and **zeaxanthin**, which contribute less to Vitamin A activity. [Practice more Community Medicine PYQs on OnCourse]

Q: According to International Health Regulations, there is no risk of spread of yellow fever if the Aedes aegypti index is kept at

below 1%. ***below 1%*** - The **International Health Regulations (IHR)** specify that a **house index** (percentage of houses infested with *Aedes aegypti* larvae) of **below 1%** is considered sufficient to prevent the spread of yellow fever. - Maintaining this low index is crucial for controlling potential outbreaks in endemic or receptive areas. *2-4%* - An *Aedes aegypti* index in this range (2-4%) indicates a **moderate risk** of yellow fever transmission, as the vector population is still significant enough to facilitate spread. - This level is **above the recommended threshold** for effective prevention according to IHR. *5-7%* - An index between 5-7% signifies an **elevated risk** of yellow fever transmission, indicating a substantial presence of the vector population. - At this level, there is a **high probability** of ongoing or impending disease outbreaks. *8-10%* - An *Aedes aegypti* index of 8-10% represents a **very high risk** of yellow fever spread, suggesting an widespread vector presence. - This range indicates a **strong potential for rapid and extensive disease transmission**. [Practice more Community Medicine PYQs on OnCourse]

Question 1

Match the diseases in List-I with their respective incubation periods in List-II and select the correct answer using the code given below:

Accepted Answer

A→1  B→2  C→3  D→4

Answer

A→4  B→3  C→2  D→1

Answer

A→1  B→4  C→3  D→2

Answer

A→3  B→4  C→2  D→1

Question 2

For a screening test, 90% specificity means that 90% of non-diseased persons will give a

Accepted Answer

True negative result

Answer

False negative result

Answer

True positive result

Answer

False positive result

Question 3

Berksonian bias is a selection bias which occurs in

Accepted Answer

Hospital based studies

Answer

Natural exposure studies

Answer

Community based studies

Answer

Laboratory based studies

Question 4

Among the following, which has the highest quantity of retinol (Vitamin A) activity per 100 g of fruit?

Accepted Answer

Ripe Mango

Answer

Papaya

Answer

Tomato

Answer

Orange

Question 5

According to International Health Regulations, there is no risk of spread of yellow fever if the Aedes aegypti index is kept at

Accepted Answer

below 1%

Answer

2-4%

Answer

5-7%

Answer

8-10%

Question 6

During the process of chlorination of water, the disinfecting action of chlorine is due to the formation of

Accepted Answer

Hypochlorous acid and hypochlorite ions

Answer

Chlorine gas only

Answer

Hydrochloric acid only

Answer

Hypochlorous acid only

Question 7

Kata thermometer is used for recording :

Accepted Answer

Low air velocities

Answer

Relative humidity of the air

Answer

Mean radiant temperature

Answer

Maximum and minimum temperature

Question 8

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 9

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 10

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

UPSC-CMS 2009 — Community Medicine