NEET-PG 2013 Practice Questions

Q: T cells in lymph node are present in:

Paracortical area. ***Paracortical area*** - The **paracortical area** contains a high concentration of **T cells**, particularly activated T cells in response to antigenic stimulation [1]. - It plays a crucial role in **immune responses**, bridging the cortex and medulla of the lymph node [1]. *Mantle layer* - The **mantle layer** surrounds the follicles and primarily consists of **B cells**, not T cells. - It is involved in the initial immune response but does not contain a significant number of T lymphocytes. *Medullary cords* - **Medullary cords** mainly contain **plasma cells** and macrophages, with very few T cells present. - Their primary function is the secretion of antibodies rather than T cell activation or response. *Cortical follicles* - **Cortical follicles** are primarily sites for **B cell activation and proliferation**. - While they may have some T cells at their periphery, the majority of T cells are located in the paracortical area.

Q: What is the number of variable regions present on each light and heavy chain of an antibody?

1. ***1*** - Each **light chain** and **heavy chain** within an antibody molecule contains **one variable region (V domain)**. - These variable regions are crucial for **antigen binding specificity**, as they combine to form the antigen-binding site. - The variable domain is located at the **N-terminal end** of each chain. *2* - While a complete antibody molecule has **two antigen-binding sites** (bivalent), each formed by pairing of VH and VL domains, individual chains possess only **one variable region each**. - The number '2' refers to the total number of identical binding sites on the intact antibody, not the number of variable regions per chain. *3* - The number **3** does not correspond to the number of variable regions on individual chains. - This might be confused with the **three complementarity-determining regions (CDRs)** present within each variable domain (CDR1, CDR2, CDR3), which are hypervariable loops that directly contact the antigen. *4* - The number **4** is incorrect for variable regions. - This number corresponds to the total number of **polypeptide chains** in a complete IgG antibody (2 heavy + 2 light chains), or the number of **constant domains** in some heavy chain isotypes (IgM, IgE have 4 CH domains).

Q: What is a limitation of the case fatality rate?

Time period not specified. ***Time period not specified*** - The **case fatality rate (CFR)** is sometimes presented without a clear time frame, making it difficult to compare across different studies or diseases. - A CFR calculated over **24 hours** is vastly different from one calculated over **30 days** or **one year**, yet both could be presented simply as "CFR" *Not useful in acute infectious disease* - The CFR is highly **useful** in acute infectious diseases, as it directly measures the **severity** and immediate impact of an outbreak. - It helps public health officials understand the **lethality** of an infectious agent and aids in resource allocation and intervention strategies. *Not related to virulence* - **Case fatality rate** is directly related to **virulence**, as it reflects the proportion of affected individuals who die from the disease. - A higher CFR indicates a more **virulent pathogen** or a more severe disease process. *It is not related to survival rate* - The **case fatality rate** is inherently linked to the **survival rate**; they are complementary measures. - If the CFR is X%, then the associated survival rate is (100 - X)%, representing the proportion of cases that do not die from the disease.

Q: To achieve neonatal tetanus elimination, the incidence of neonatal tetanus per 1000 live births should be reduced to less than:

1.0. ***1.0*** - The international target for **neonatal tetanus elimination (NTE)** as defined by WHO/UNICEF is an incidence rate of **less than 1 case per 1,000 live births per year** in every district of a country. - This is the globally recognized threshold for declaring that neonatal tetanus has been eliminated as a public health problem. - Countries achieving this target at the district level are considered to have achieved NTE. *0.1* - While 0.1 per 1,000 live births represents an extremely low incidence, this is not the WHO-defined threshold for **neonatal tetanus elimination**. - The elimination target is less stringent at <1 per 1,000 live births, making disease control achievable while still representing a major public health success. *0.2* - An incidence of 0.2 per 1,000 live births, though very low, is not the internationally recognized threshold for **neonatal tetanus elimination**. - The established WHO/UNICEF target is <1 per 1,000 live births in every district. *0.5* - An incidence of 0.5 per 1,000 live births indicates excellent control of neonatal tetanus but is not the specific cut-off value. - The WHO criterion for elimination is less than 1 case per 1,000 live births per year at the district level.

Q: Immersion syndrome is also known as?

Hydrocution. ***Hydrocution*** - **Immersion syndrome**, or hydrocution, is a sudden death that occurs immediately upon immersion in cold water. - It is believed to be caused by a **vasovagal reflex** triggered by the sudden temperature change, leading to cardiac arrest. *Wet drowning* - This term refers to conventional drowning where an individual inhales water, leading to respiratory compromise and death. - It is characterized by the presence of **fluid in the lungs**, which is not the primary mechanism in immersion syndrome. *Dry drowning* - **Dry drowning** occurs when water does not enter the lungs; instead, the glottis spasms and closes, preventing air and water from entering. - This leads to suffocation, often hours after the initial water exposure, and is distinct from the immediate cardiac event of immersion syndrome. *Secondary drowning* - **Secondary drowning**, or delayed drowning, refers to complications that arise hours or days after a near-drowning incident due to inhaled water causing pulmonary edema. - It involves a delayed physiological response rather than an immediate reflex.

Q: Which of the following is called Preisz-Nocard bacillus?

C. pseudotuberculosis. ***C. pseudotuberculosis*** - This bacterium is historically known as the **Preisz-Nocard bacillus**, named after its discoverers. - It is an important pathogen in animals, causing conditions like **caseous lymphadenitis** in sheep and goats. *C. diphtheriae* - This bacterium causes **diphtheria** and is known for producing a potent **exotoxin** that can lead to systemic complications. - It forms a characteristic **pseudomembrane** in the throat and is not associated with the Preisz-Nocard designation. *M. tuberculosis* - This is the causative agent of **tuberculosis** in humans, primarily affecting the lungs. - It is known for its **acid-fast staining** property and a complex pathogenesis involving granuloma formation. *Mycoplasma* - This genus includes bacteria that lack a **cell wall**, making them resistant to many common antibiotics. - They are known for causing various infections, including **atypical pneumonia** and genitourinary tract infections, but are not referred to as the Preisz-Nocard bacillus.

Q: Which among the following is an absolute contraindication of Hormone replacement therapy?

Breast carcinoma. ### Breast carcinoma - Hormone replacement therapy (HRT) is **contraindicated** in breast carcinoma because many breast cancers are **estrogen-receptor positive**, meaning estrogen can stimulate their growth [1]. - Using HRT in patients with a history of breast cancer significantly increases the risk of **recurrence** or **progression** of the disease [1]. *Endometriosis* - Endometriosis is not an **absolute contraindication**; HRT can sometimes be used in women with a history of endometriosis, especially if a hysterectomy and bilateral oophorectomy have been performed. - However, unopposed estrogen therapy might **exacerbate** remaining endometrial implants, so a combined estrogen-progestin regimen is typically preferred [1]. *Heart disease* - While HRT has been shown to have **risks** in women with established coronary heart disease, it is not an absolute contraindication for all forms of heart disease. - The **Women's Health Initiative study** demonstrated increased cardiovascular events in older women initiating HRT, but current guidelines suggest that timing of initiation is crucial and benefits may outweigh risks for younger postmenopausal women. *Osteoarthritis* - Osteoarthritis is **not a contraindication** to HRT; in fact, some studies suggest that estrogen may have protective effects on cartilage [2]. - HRT is neither a treatment nor a contraindication for osteoarthritis and does not significantly impact its progression or severity [2].

Q: ABO isoantibodies are of which class?

IgM. ***IgM*** - Naturally occurring **ABO isoantibodies** are predominantly of the **IgM class**. - These **pentameric antibodies** are highly effective at causing **agglutination** of incompatible red blood cells, which is crucial in transfusion reactions [1]. *IgG* - While IgG antibodies can be formed against ABO antigens (e.g., in hemolytic disease of the newborn), the **naturally occurring isoantibodies** are primarily IgM. - IgG antibodies are **monomeric** and can cross the **placenta**, which is a key difference from the primary IgM ABO antibodies. *IgD* - **IgD** antibodies are primarily found on the surface of **B cells** and play a role in B cell activation. - They are **not a primary mediator** of ABO isoantibody response or red blood cell agglutination. *IgA* - **IgA** antibodies are predominantly found in **mucosal secretions** and play a role in mucosal immunity. - While some IgA may be present, it is **not the predominant class** for naturally occurring ABO isoantibodies involved in transfusion reactions. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 154-155.

Q: An Englishman travels to a place which is resistant to chloroquine and mefloquine. What should he take as prophylaxis?

Atovaquone-proguanil. ***Atovaquone-proguanil*** - This combination, known as **Malarone**, is the most appropriate prophylactic agent for areas with **multi-drug resistant malaria**, including resistance to chloroquine and mefloquine [1], [2]. - It targets multiple stages of the parasite life cycle, providing excellent protection and is generally well-tolerated with specific **WHO and CDC recommendations** for chloroquine and mefloquine resistant areas [1], [3]. *Primaquine* - **Primaquine** is primarily used for **causal prophylaxis** against *P. vivax* and *P. ovale* to prevent relapse, not as primary prophylaxis [2]. - It is not typically recommended as the primary prophylactic agent in areas with **chloroquine and mefloquine resistance** and requires **G6PD testing** due to risk of hemolysis [1]. *Proguanil* - While proguanil is used for malaria prophylaxis, **proguanil alone** is not effective enough for prophylaxis in areas with multi-drug resistant malaria. - It is typically used in **combination with atovaquone** rather than as monotherapy for effective protection [3]. *Doxycycline* - **Doxycycline** is also an effective prophylactic agent for areas with **chloroquine and mefloquine-resistant malaria** and is commonly recommended [1], [2]. - While effective, it can cause **photosensitivity** and **gastrointestinal upset**, making atovaquone-proguanil the preferred first-line choice.

Question 1

T cells in lymph node are present in:

Accepted Answer

Paracortical area

Answer

Mantle layer

Answer

Medullary cords

Answer

Cortical follicles

Question 2

What is the number of variable regions present on each light and heavy chain of an antibody?

Accepted Answer

1

Answer

2

Answer

3

Answer

4

Question 3

What is the most critical priority in reducing mortality in the immediate aftermath of natural disasters?

Accepted Answer

Triage and prioritization of casualties

Answer

Disease surveillance and outbreak prevention

Answer

Establishment of temporary medical facilities

Answer

Psychological support and trauma counseling

Question 4

What is a limitation of the case fatality rate?

Accepted Answer

Time period not specified

Answer

Not useful in acute infectious disease

Answer

Not related to virulence

Answer

It is not related to survival rate

Question 5

To achieve neonatal tetanus elimination, the incidence of neonatal tetanus per 1000 live births should be reduced to less than:

Accepted Answer

1.0

Answer

0.1

Answer

0.5

Answer

0.2

Question 6

Immersion syndrome is also known as?

Accepted Answer

Hydrocution

Answer

Wet drowning

Answer

Dry drowning

Answer

Secondary drowning

Question 7

Which of the following is called Preisz-Nocard bacillus?

Accepted Answer

C. pseudotuberculosis

Answer

C. diphtheriae

Answer

M. tuberculosis

Answer

Mycoplasma

Question 8

Which among the following is an absolute contraindication of Hormone replacement therapy?

Accepted Answer

Breast carcinoma

Answer

Endometriosis

Answer

Heart disease

Answer

Osteoarthritis

Question 9

ABO isoantibodies are of which class?

Accepted Answer

IgM

Answer

IgG

Answer

IgD

Answer

IgA

Question 10

An Englishman travels to a place which is resistant to chloroquine and mefloquine. What should he take as prophylaxis?

Accepted Answer

Atovaquone-proguanil

Answer

Primaquine

Answer

Doxycycline

Answer

Proguanil

NEET-PG 2013

Anatomy

Biochemistry

Community Medicine

Forensic Medicine

Microbiology

Obstetrics and Gynecology

Pathology

Pharmacology