Internal Medicine
2 questionsWhich type of malaria is most commonly associated with renal failure?
Which species of malaria is associated with nephrotic syndrome?
NEET-PG 2012 - Internal Medicine NEET-PG Practice Questions and MCQs
Question 701: Which type of malaria is most commonly associated with renal failure?
- A. Falciparum (Correct Answer)
- B. Vivax
- C. Malariae
- D. Ovale
Explanation: ***Falciparum*** - **Plasmodium falciparum** is notorious for its ability to cause severe and complicated malaria, including **renal failure** due to its high parasitic biomass and tendency to block microvasculature [1]. - The parasite causes red blood cells to become **sticky**, leading to sequestration in capillaries of vital organs, including the kidneys, resulting in acute tubular necrosis [1]. *Vivax* - **Plasmodium vivax** typically causes milder forms of malaria, though it can occasionally lead to severe manifestations, **renal complications are rare** compared to P. falciparum [1]. - While it can cause some organ dysfunction, it generally does not cause the severe multi-organ involvement, particularly **acute renal failure**, that P. falciparum is known for [1]. *Malariae* - **Plasmodium malariae** is associated with a chronic form of malaria and is known to cause **nephrotic syndrome** (specifically malarial nephropathy) due to immune complex deposition, rather than acute renal failure [1]. - The renal pathology in P. malariae infection is typically a **glomerulonephritis** that develops after repeated infections, which is distinct from the acute renal failure seen with P. falciparum [1]. *Ovale* - **Plasmodium ovale** is the least common type of malaria and causes a benign form of the disease, similar to P. vivax [1]. - It rarely, if ever, causes severe complications like **renal failure** [1].
Question 702: Which species of malaria is associated with nephrotic syndrome?
- A. P. vivax
- B. P. falciparum
- C. P. malariae (Correct Answer)
- D. P. ovale
Explanation: ***P. malariae*** - *P. malariae* infection is classically associated with **quartan fever** and can lead to **nephrotic syndrome**, particularly in children [1]. - The mechanism involves the deposition of immune complexes in the glomeruli, causing **membranoproliferative glomerulonephritis**. *P. vivax* - *P. vivax* is known for causing **benign tertian malaria** and frequently leads to **relapses** due to hypnozoites in the liver [1]. - While it can cause renal dysfunction, **nephrotic syndrome** is not a characteristic complication. *P. falciparum* - *P. falciparum* is responsible for the most severe form of malaria, often complicated by **cerebral malaria**, **acute renal failure**, and **blackwater fever** [1]. - Renal complications typically present as **acute tubular necrosis** rather than nephrotic syndrome. *P. ovale* - *P. ovale* causes **mild tertian malaria** similar to *P. vivax* and is also known for **relapses** due to hypnozoites [1]. - It is the least common form of malaria and is not typically associated with **nephrotic syndrome**.
Microbiology
5 questionsWhat is a key distinguishing feature of meningococci compared to gonococci?
Regarding fungal cell wall, all are true except:
Binding of gp120 causes:
What type of test is the Paul-Bunnell reaction?
Which antibody is elevated in parasitic infections?
NEET-PG 2012 - Microbiology NEET-PG Practice Questions and MCQs
Question 701: What is a key distinguishing feature of meningococci compared to gonococci?
- A. Are intracellular pathogens
- B. Are catalase positive
- C. Ferment maltose (Correct Answer)
- D. Possess a capsule
Explanation: ***Ferment maltose*** - *Neisseria meningitidis* ferments both **glucose and maltose**, which is a key biochemical characteristic used for its identification. - *Neisseria gonorrhoeae* only ferments **glucose**, differentiating it from meningococci. *Are intracellular pathogens* - Both **meningococci** (*Neisseria meningitidis*) and **gonococci** (*Neisseria gonorrhoeae*) are facultative intracellular pathogens, meaning they can survive and replicate within host cells. - Therefore, this feature does not distinguish between the two. *Are catalase positive* - Both *Neisseria meningitidis* and *Neisseria gonorrhoeae* are **catalase-positive**, meaning they produce the enzyme catalase. - This characteristic is common to both and thus cannot be used to differentiate them. *Possess a capsule* - While *Neisseria meningitidis* possesses a **polysaccharide capsule**, which is a major virulence factor, *Neisseria gonorrhoeae* typically **lacks a capsule**. - However, the ability to ferment maltose is a more direct and commonly used biochemical distinguishing feature in laboratory settings.
Question 702: Regarding fungal cell wall, all are true except:
- A. Contains chitin
- B. Prevent osmotic damage
- C. Does not contain peptidoglycan
- D. Azoles act on them (Correct Answer)
Explanation: ***Azoles act on them*** - **Azole antifungals** primarily target the **ergosterol synthesis** pathway, specifically inhibiting the **lanosterol 14-alpha-demethylase** enzyme, which is located in the fungal cell membrane, not the cell wall. - While the cell wall is crucial for fungal viability, agents targeting it (e.g., **echinocandins**) are distinct from azoles. *Contains chitin* - The fungal cell wall is indeed a complex structure composed of various carbohydrates, with **chitin** being a major structural polysaccharide that provides rigidity. - Chitin is a **beta-(1,4)-linked polymer of N-acetylglucosamine** and is a unique component distinguishing fungal cells from animal cells. *Prevent osmotic damage* - The rigid fungal cell wall provides structural support and protects the cell from **environmental stresses**, particularly **osmotic lysis** in hypotonic environments. - It maintains the cell's integrity against internal **turgor pressure**, which is essential for fungal growth and survival. *Does not contain peptidoglycan* - Fungal cell walls are distinct from bacterial cell walls in their composition; they **do not contain peptidoglycan**. - **Peptidoglycan** is a characteristic component of bacterial cell walls, which is targeted by antibiotics like penicillins.
Question 703: Binding of gp120 causes:
- A. Infection of target cell
- B. Facilitation of co-receptor binding (Correct Answer)
- C. Fusing of virus and target cell
- D. None of the options
Explanation: ***Facilitation of co-receptor*** - **gp120** binding to the **CD4 receptor** on target cells induces a conformational change in gp120, which then exposes or creates a binding site for a **chemokine co-receptor** (CCR5 or CXCR4). - This interaction is crucial for the subsequent steps of viral entry, as it allows the virus to make further contact with the cell surface. *Infection of target cell* - While binding of gp120 is the *first step* in infection, it does not directly cause the infection itself. - Infection occurs after a series of events including co-receptor binding, membrane fusion, and reverse transcription. *Fusing of virus and target cell* - **Fusion** of the viral and cellular membranes is primarily mediated by **gp41**, which is part of the gp160 envelope glycoprotein complex alongside gp120. - This fusion event *follows* the binding of gp120 to CD4 and the co-receptor, as gp120 binding initiates the conformational changes that expose and activate gp41. *None of the options* - One of the provided options accurately describes a direct consequence of gp120 binding, making this option incorrect.
Question 704: What type of test is the Paul-Bunnell reaction?
- A. Agglutination (Correct Answer)
- B. CF
- C. Precipitation
- D. Flocculation test
Explanation: ***Agglutination*** - The **Paul-Bunnell reaction** is an **agglutination test** used to detect specific antibodies in infectious mononucleosis. - It identifies **heterophile antibodies** that agglutinate **sheep red blood cells**. *CF* - **Complement Fixation (CF) tests** measure antibody or antigen by observing the *fixation* of complement components. - This method is distinct from the **direct clumping** of cells seen in agglutination. *Precipitation* - **Precipitation reactions** involve soluble antigens and antibodies forming an **insoluble lattice** that settles out of solution. - These reactions detect soluble complexes, not the clumping of cells. *Flocculation test* - **Flocculation tests** are a type of **precipitation reaction** where *finely dispersed particles* form visible clumps (floccules). - While related to precipitation, the Paul-Bunnell reaction specifically involves the *agglutination of red blood cells*.
Question 705: Which antibody is elevated in parasitic infections?
- A. IgA
- B. IgE (Correct Answer)
- C. IgG
- D. IgM
Explanation: **Correct: IgE** - **IgE** is centrally involved in the immune response to **parasitic infections**, particularly helminths. - This antibody promotes the release of inflammatory mediators from **mast cells** and **basophils**, leading to the expulsion of parasites. - Elevated IgE is a **characteristic finding** in helminthic infections and is used diagnostically. *Incorrect: IgA* - **IgA** is primarily found in **mucosal secretions** and plays a key role in protecting against pathogens at mucosal surfaces. - While it has a role in general immunity, it is **not the primary antibody** involved in the systemic response to parasitic infections. *Incorrect: IgG* - **IgG** is the most abundant antibody in serum and provides **long-term immunity** against many pathogens. - While IgG levels may rise in response to chronic parasitic infections, it is **not the characteristic or primary antibody** elevated in active or initial parasitic responses. *Incorrect: IgM* - **IgM** is the first antibody produced during a **primary immune response** and is important for activating the complement system. - While it indicates an early infection, it is **less specific** for parasitic infections compared to IgE.
Obstetrics and Gynecology
1 questionsWhat is the most common primary malignancy of the fallopian tube?
NEET-PG 2012 - Obstetrics and Gynecology NEET-PG Practice Questions and MCQs
Question 701: What is the most common primary malignancy of the fallopian tube?
- A. Squamous cell carcinoma
- B. Serous carcinoma (Correct Answer)
- C. Teratoma
- D. Choriocarcinoma
Explanation: ***Serous carcinoma*** - **Serous carcinoma** is the most common type of **primary** fallopian tube malignancy, accounting for approximately **90%** of primary tumors. - It often shares molecular and morphological similarities with **high-grade serous ovarian carcinoma** and **primary peritoneal cancer**. - Note: While primary fallopian tube cancer is rare (0.14-1.8% of gynecologic malignancies), metastatic disease to the fallopian tube is more common, typically from **ovarian or endometrial** primaries. *Squamous cell carcinoma* - **Squamous cell carcinoma** is exceedingly rare in the fallopian tube, as the tubal lining is composed of **ciliated and secretory columnar epithelium**, not squamous epithelium. - When present, it usually represents **metastatic spread** from cervical or other primary sites. *Teratoma* - **Teratomas** are germ cell tumors typically found in the **ovaries**, composed of tissues from multiple germ layers. - Primary teratomas of the fallopian tube are **extraordinarily rare** and not the most common primary malignancy. *Choriocarcinoma* - **Choriocarcinoma** is a highly malignant **gestational trophoblastic neoplasm** usually associated with pregnancy complications. - It primarily occurs in the **uterus**, and primary fallopian tube choriocarcinoma is **exceptionally uncommon**.
Pathology
2 questionsWhich of the following germ cell tumors is benign?
Ewing's sarcoma arises from which type of cells?
NEET-PG 2012 - Pathology NEET-PG Practice Questions and MCQs
Question 701: Which of the following germ cell tumors is benign?
- A. Seminoma
- B. Dermoid cyst (Correct Answer)
- C. Embryonal carcinoma
- D. Yolk sac tumor
Explanation: ***Seminoma*** - Seminomas are well-known malignant **germ cell tumors**, primarily affecting young males [2]. - They are associated with elevated **human chorionic gonadotropin (hCG)** and can spread to lymph nodes [3]. *Leydig cell tumor* - These tumors are usually **benign** and arise from Leydig cells in the testes. - While they can produce **testosterone**, they do not typically exhibit malignancy. *Sertoli cell tumor* - Sertoli cell tumors are also generally **benign** and arise from Sertoli cells in the testes. - They lack the malignant behavior seen in seminomas and have a low rate of metastasis [1]. *Dermoid cyst* - Dermoid cysts are **benign** mature teratomas, commonly found in the ovaries or testicles. - They can contain different tissue types (like hair, fat, and teeth) but are not malignant. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 512-513. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lower Urinary Tract and Male Genital System, pp. 979-980. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lower Urinary Tract and Male Genital System, pp. 980-982.
Question 702: Ewing's sarcoma arises from which type of cells?
- A. G cells
- B. Totipotent cells
- C. Neurons
- D. Primitive neuroectodermal cells (Correct Answer)
Explanation: ***Primitive neuroectodermal cells*** - **Ewing's sarcoma** is a malignant small round blue cell tumor largely believed to arise from **primitive neuroectodermal cells**. - This cellular origin explains why it's often grouped under the term **PNET (Primitive Neuroectodermal Tumor)**. *G cells* - **G cells** are specialized **enteroendocrine cells** found in the stomach and duodenum that secrete **gastrin**. - They are involved in regulating gastric acid secretion and have no association with Ewing's sarcoma. *Totipotent cells* - **Totipotent cells** have the ability to differentiate into **any type of cell**, including embryonic and extraembryonic tissues. - While all cancers originate from cellular changes, Ewing's sarcoma originates from a more specific, committed cell lineage, not totipotent stem cells. *Neurons* - **Neurons** are the basic functional units of the nervous system, responsible for transmitting electrical and chemical signals. - While Ewing's sarcoma has neuroectodermal characteristics, it does not arise from fully differentiated neurons but rather from more **primitive precursors**.