Biochemistry
2 questionsWhich chromosome is responsible for the production of MIF?
Which of the following statements about DNA polymerase I is correct?
NEET-PG 2018 - Biochemistry NEET-PG Practice Questions and MCQs
Question 101: Which chromosome is responsible for the production of MIF?
- A. Y chromosome
- B. Chromosome 22 (Correct Answer)
- C. Chromosome 16
- D. X Chromosome
Explanation: ***Chromosome 22*** * The **macrophage migration inhibitory factor (MIF)** gene is located on **chromosome 22q11.2**, making it responsible for MIF production. * MIF is a crucial **pro-inflammatory cytokine** involved in immune responses and inflammation. *Chromosome 16* * Chromosome 16 contains genes like those for **alpha-globin** and **CDH1 (E-cadherin)**, not MIF. * Disorders associated with chromosome 16 include **alpha-thalassemia** and certain types of **hereditary diffuse gastric cancer**. *X Chromosome* * The X chromosome contains genes primarily involved in **sex determination** and various X-linked disorders. * Examples include genes like **DMD (Duchenne muscular dystrophy)** and **F8 (hemophilia A)**, but not MIF. *Y chromosome* * The Y chromosome contains genes, such as **SRY (sex-determining region Y)**, that are critical for male sexual development. * It plays a role in male-specific traits and conditions like **infertility** but does not carry the gene for MIF.
Question 102: Which of the following statements about DNA polymerase I is correct?
- A. Participates in the synthesis of Okazaki fragments.
- B. Is the primary enzyme for DNA replication in bacteria
- C. Involved in DNA repair processes. (Correct Answer)
- D. Not essential for DNA replication in bacteria.
Explanation: ***Involved in DNA repair processes.*** - **DNA polymerase I** possesses **5' to 3' exonuclease activity**, which is crucial for removing **RNA primers** and damaged DNA segments during DNA repair. - Its **DNA repair function** is essential for maintaining genome integrity by excising incorrect nucleotides and filling the gaps. - DNA pol I plays a key role in **nick translation** and **gap filling** after primer removal during DNA replication. *Participates in the synthesis of Okazaki fragments.* - **DNA polymerase III** is the primary enzyme responsible for synthesizing **Okazaki fragments** on the lagging strand during bacterial DNA replication. - While DNA polymerase I does **process** Okazaki fragments by removing RNA primers and filling gaps, it does not *synthesize* them. *Is the primary enzyme for DNA replication in bacteria* - **DNA polymerase III** is the main enzyme responsible for the bulk of DNA synthesis during replication in **bacteria**. - DNA polymerase I plays a more specialized role in **primer removal** and **gap filling** rather than primary elongation. *Not essential for DNA replication in bacteria.* - **DNA polymerase I** is **essential** for bacterial viability despite not being the primary replicative polymerase. - Its crucial role in **primer removal** and **gap filling** after primer excision is indispensable for completing DNA replication and repair processes.
Internal Medicine
3 questionsWhich of the following statements is true regarding Hemophilia A?
Which condition is associated with congenital adrenal hyperplasia?
In Bartter syndrome defect is seen in:
NEET-PG 2018 - Internal Medicine NEET-PG Practice Questions and MCQs
Question 101: Which of the following statements is true regarding Hemophilia A?
- A. PT is typically prolonged
- B. PTT is typically normal
- C. Serum levels of factor VIII are increased
- D. Deficiency of factor VIII (Correct Answer)
Explanation: ***Serum levels of factor VIII are decreased*** - Hemophilia A is characterized by a **deficiency of factor VIII** [1], which leads to decreased serum levels of this factor. - This deficiency results in a **prolonged activated partial thromboplastin time (aPTT)** [3] but normal prothrombin time (PT). *Deficiency of factor IX* - This escribes **Hemophilia B**, which is caused by a deficiency of factor IX, not factor VIII as in Hemophilia A [1]. - Hemophilia A specifically refers to the **deficiency of factor VIII** [1][2], where factor IX is not involved. *PT increased* - In Hemophilia A, the **prothrombin time (PT)** is usually normal because the intrinsic pathway is not affected [3]. - The primary test affected is the **activated partial thromboplastin time (aPTT)**, which is prolonged due to factor VIII deficiency [3]. *FIT decreased* - The term "FIT" is not standard in the context of hemophilia; it might refer to some other tests or assessments not directly relevant to factor levels. - The relevant lab finding in Hemophilia A is the **decrease in factor VIII** [2], not a direct measure of "FIT".
Question 102: Which condition is associated with congenital adrenal hyperplasia?
- A. Male pseudohermaphroditism
- B. True pseudohermaphroditism
- C. Sequential pseudohermaphroditism
- D. Female pseudohermaphroditism (Correct Answer)
Explanation: ***Female pseudohermaphroditism*** - In **21-hydroxylase deficiency**, the most common form of CAH, virilization of a female fetus occurs due to excessive **androgen production** [2], [3]. - This leads to ambiguous genitalia in genetically female (XX) infants, presenting as **female pseudohermaphroditism** [2]. *Male pseudohermaphroditism* - This condition occurs when a **genetically male individual (XY)** has external genitalia that are undervirilized or ambiguous. - It is typically caused by inadequate **androgen synthesis** or action, such as in **androgen insensitivity syndrome**, which is not the primary presentation of CAH [2]. *True pseudohermaphroditism* - This term refers to individuals who possess both **ovarian and testicular tissue**, either in separate gonads or as ovotestes [1], [2]. - It is distinct from CAH, where gonadal tissue is uniform (either ovaries or testes), but the external genitalia are ambiguous due to hormonal imbalances [2]. *Sequential pseudohermaphroditism* - This term is not a recognized medical classification for conditions like CAH. - It does not describe a specific developmental anomaly of the reproductive system related to adrenal function.
Question 103: In Bartter syndrome defect is seen in:
- A. Defect in proximal convoluted tubule (PCT)
- B. Defect in distal convoluted tubule (DCT)
- C. No defect
- D. Defect in thick ascending limb of loop of Henle (Correct Answer)
Explanation: ***Defect in thick ascending limb of loop of Henle*** - Bartter syndrome results from a **genetic defect** affecting the activity of the **Na-K-2Cl cotransporter (NKCC2)** in the thick ascending limb of the loop of Henle. - This defect impairs **sodium, potassium, and chloride reabsorption**, leading to their increased excretion and characteristic electrolyte imbalances. *Defect in proximal convoluted tubule (PCT)* - Defects in the **proximal convoluted tubule** are typically associated with conditions like **Fanconi syndrome**, affecting reabsorption of glucose, amino acids, phosphate, and bicarbonate [1]. - This does not align with the characteristic **electrolyte imbalances** seen in Bartter syndrome, particularly hypokalemia and metabolic alkalosis. *Defect in distal convoluted tubule (DCT)* - Defects in the **distal convoluted tubule** are seen in conditions like **Gitelman syndrome**, which affects the Na-Cl cotransporter. - While both Bartter and Gitelman syndromes present with hypokalemia and metabolic alkalosis, the specific transporter affected and the severity of certain electrolyte disturbances differ. *No defect* - Bartter syndrome is a well-defined **genetic disorder** characterized by specific renal tubular defects. - Stating there is no defect is incorrect, as the syndrome arises directly from impaired renal tubule function.
Obstetrics and Gynecology
2 questionsExtramammary Paget's disease of the vulva is most commonly associated with which other cancer?
Which of the following is not a high-risk pregnancy?
NEET-PG 2018 - Obstetrics and Gynecology NEET-PG Practice Questions and MCQs
Question 101: Extramammary Paget's disease of the vulva is most commonly associated with which other cancer?
- A. Vulvar cancer (Correct Answer)
- B. Vaginal cancer
- C. Cervical cancer
- D. Uterine cancer
Explanation: ***Vulvar cancer*** - **Extramammary Paget's disease (EMPD)** frequently presents in the vulvar region and is associated with an underlying **adenocarcinoma** in up to 30% of cases. - The disease involves intraepithelial adenocarcinoma cells that can spread locally and, in some instances, indicates a synchronous or metachronous **internal malignancy**, often of genitourinary or gastrointestinal origin, but primarily vulvar adenocarcinoma in this context. *Vaginal cancer* - While Paget's disease can occur in other anogenital areas, its association with **primary vaginal cancer** is much less common compared to vulvar involvement. - **Vaginal Paget's disease** is rare and usually represents secondary spread from a vulvar primary or an underlying bladder/urethral carcinoma. *Cervical cancer* - **Paget's disease** is not typically associated with **cervical cancer**. Cervical cancers are predominantly squamous cell carcinomas or adenocarcinomas arising from the transformation zone. - While cervical adenocarcinoma can present with similar cells to Paget's, it is a distinct entity and not a common association. *Uterine cancer* - **Uterine cancer**, primarily endometrial carcinoma, has no direct or common association with **Paget's disease**. - Paget's disease primarily affects the skin and can be associated with underlying gland cancers, but these are generally in proximity to the epidermal involvement rather than distant uterine sites.
Question 102: Which of the following is not a high-risk pregnancy?
- A. Age 25-30 years (Correct Answer)
- B. Diabetes mellitus
- C. Previous history of manual removal of placenta
- D. Anemia
Explanation: ***Age 25-30 years*** - An age of **25-30 years** is generally considered the optimal reproductive age range, and pregnancies within this bracket are typically classified as low-risk based on age alone. - This age range carries the lowest statistical risk for both maternal and fetal complications, assuming no other co-morbidities. *Previous history of manual removal of placenta* - A previous history of manual removal of the placenta indicates a risk factor for **recurrent placental retention** or **morbidly adherent placenta** in future pregnancies, making it a high-risk factor. - This history suggests an increased likelihood of complications such as **postpartum hemorrhage** and can influence the management of subsequent deliveries. *Anemia* - **Anemia** in pregnancy, especially severe iron deficiency anemia, is considered a high-risk factor due to increased maternal and fetal morbidity. - It can lead to complications such as **preterm delivery**, **low birth weight**, and difficulties tolerating blood loss during delivery. *Diabetes mellitus* - **Diabetes mellitus**, whether pre-existing or gestational, makes a pregnancy high-risk due to potential adverse effects on both the mother and the fetus. - Risks include **preeclampsia**, **macrosomia**, **neonatal hypoglycemia**, and **congenital anomalies**.
Pathology
1 questionsIn which type of Hodgkin's lymphoma are classical Reed-Sternberg cells most characteristically observed?
NEET-PG 2018 - Pathology NEET-PG Practice Questions and MCQs
Question 101: In which type of Hodgkin's lymphoma are classical Reed-Sternberg cells most characteristically observed?
- A. Lymphocyte depleted
- B. Nodular sclerosis
- C. Lymphocyte predominance
- D. Mixed cellularity Hodgkin (Correct Answer)
Explanation: ***Lymphocyte predominance*** - The **Hodgkin's lymphoma (HL) lymphocyte predominance** variant characteristically displays a predominance of lymphocytes in the cellular makeup [1]. - This subtype is often associated with a better prognosis and fewer symptoms than other types of HL [1]. *Lymphocyte depleted* - This subtype features a significant decrease in lymphocytes, leading to a **higher proportion of Reed-Sternberg cells** [3]. - It typically presents with a more aggressive clinical course, which contrasts with lymphocyte predominance [3]. *Mixed cellularity hodgkin* - Mixed cellularity shows a variety of cell types, including a significant number of **Reed-Sternberg cells**, but does not demonstrate **lymphocyte predominance** [2]. - This subtype is generally found in older patients and associated with advanced disease, unlike lymphocyte predominance [2]. *Nodular sclerosis* - Nodular sclerosis subtype is characterized by **collagen bands** and a particular architecture that is distinct from lymphocyte predominance [2]. - It primarily affects younger patients and can often involve mediastinal lymph nodes; however, it does not have the features of lymphocyte predominance [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, p. 618. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, pp. 616-618. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 559-560.
Pharmacology
1 questionsEndothelin primarily acts through which type of receptors?
NEET-PG 2018 - Pharmacology NEET-PG Practice Questions and MCQs
Question 101: Endothelin primarily acts through which type of receptors?
- A. Calcium receptors
- B. General receptor type (GPCRs)
- C. Endothelin receptor type B (ETB)
- D. Endothelin receptor type A (ETA) (Correct Answer)
Explanation: ***Endothelin receptor type A (ETA)*** - **ETA receptors** are primarily responsible for the **vasoconstrictive effects** of endothelin-1 in various tissues, leading to increased vascular tone and blood pressure. - Activation of **ETA receptors** on vascular smooth muscle cells mediates signaling pathways that result in **smooth muscle contraction**. *Endothelin receptor type B (ETB)* - **ETB receptors** have dual roles, mediating both **vasoconstriction** (via smooth muscle ETB) and **vasodilation** (via endothelial ETB, stimulating nitric oxide and prostacyclin release). - They also play a significant role in **clearance of endothelin-1** from circulation. *General receptor type (GPCRs)* - While **endothelin receptors (ETA and ETB)** are indeed **G protein-coupled receptors (GPCRs)**, "General receptor type (GPCRs)" is too broad and not the most specific answer for how endothelin *primarily acts*. - Endothelin's specific effects are mediated through its dedicated subtypes of GPCRs, not the general class. *Calcium receptors* - **Calcium receptors** (e.g., calcium-sensing receptors) are involved in sensing extracellular calcium levels and regulating calcium homeostasis. - Endothelin's mechanism involves **intracellular calcium mobilization** *after* receptor activation, but it does not act *through* calcium receptors.
Physiology
1 questionsWhat is the physiological response of the kidney during shock?
NEET-PG 2018 - Physiology NEET-PG Practice Questions and MCQs
Question 101: What is the physiological response of the kidney during shock?
- A. GFR decreases
- B. Perfusion of kidney decreases
- C. Afferent arteriole resistance increases
- D. Renal blood flow decreases (Correct Answer)
Explanation: ***Renal blood flow decreases*** - During shock, the **primary and most fundamental** physiological change affecting the kidney is a marked **reduction in renal blood flow (RBF)**. - Shock triggers intense **sympathetic activation** and **renin-angiotensin system (RAS) activation**, causing preferential **vasoconstriction** of renal vessels to redirect blood to vital organs (brain, heart). - RBF can drop to as low as **20-30% of normal** in severe shock, making this the hallmark renal response. - This reduction in RBF is the **upstream event** that triggers all other renal changes during shock. *Perfusion of kidney decreases* - While technically correct, "decreased perfusion" is **essentially synonymous** with decreased blood flow in this context. - The term "renal blood flow" is the **standard physiological terminology** used in medical literature to describe this phenomenon, making it the more precise answer. *Afferent arteriole resistance increases* - This is a **mechanism** by which RBF decreases, not the overall response itself. - Increased afferent arteriolar resistance is **secondary** to sympathetic activation and angiotensin II effects during shock. - It describes the "how" rather than the "what" of the kidney's response. *GFR decreases* - GFR reduction is a **consequence** of decreased RBF and increased afferent arteriolar resistance. - While clinically important (oliguria/acute kidney injury), it's a **downstream effect** rather than the primary physiological response. - The relationship: ↓RBF → ↓Glomerular hydrostatic pressure → ↓GFR