Community Medicine
1 questionsWhat is the statistical term for the value that occurs most frequently in a data set?
NEET-PG 2012 - Community Medicine NEET-PG Practice Questions and MCQs
Question 491: What is the statistical term for the value that occurs most frequently in a data set?
- A. Median
- B. Mode (Correct Answer)
- C. Standard deviation
- D. Mean
Explanation: ***Mode*** - The **mode** is the value that appears most often in a set of data. - It represents the **most frequent observation** within a dataset. *Median* - The **median** is the middle value in a dataset when the values are arranged in ascending or descending order. - It is a measure of **central tendency** that is less affected by outliers than the mean. *Standard deviation* - **Standard deviation** measures the amount of variation or dispersion of a set of values. - A low standard deviation indicates that the data points tend to be **close to the mean**. *Mean* - The **mean** is the arithmetic average of a dataset, obtained by summing all values and dividing by the number of values. - It is a common measure of **central tendency** but can be influenced by extreme values.
Ophthalmology
1 questionsHow is the angle of squint measured?
NEET-PG 2012 - Ophthalmology NEET-PG Practice Questions and MCQs
Question 491: How is the angle of squint measured?
- A. Gonioscopy
- B. Prism (Correct Answer)
- C. Retinoscopy
- D. Keratometry
Explanation: ***Prism*** - The **angle of squint**, which indicates the deviation of the eyes, is most accurately measured using **prisms** in conjunction with the **prism cover test** or **alternate prism cover test**. - Prisms quantify the degree of ocular deviation in **prism diopters** by neutralizing the misalignment so that the light falls correctly on the fovea. *Gonioscopy* - This technique is used to examine the **anterior chamber angle** of the eye, which is relevant for diagnosing conditions like **glaucoma**. - It does not involve measuring the angle of ocular deviation or misalignment of the eyes. *Retinoscopy* - Retinoscopy is an objective method to determine the **refractive error** of the eye (e.g., myopia, hyperopia, astigmatism). - While it assesses the eye's ability to focus light, it does not directly measure the angle of a squint. *Keratometry* - Keratometry measures the **curvature of the cornea**, primarily used for fitting contact lenses or calculating intraocular lens power for cataract surgery. - It does not assess the alignment of the eyes or the magnitude of a squint.
Pathology
3 questionsIn which condition is retinal astrocytoma commonly seen?
ER positive status in carcinoma breast indicates?
Which gene mutation is commonly associated with malignant melanoma?
NEET-PG 2012 - Pathology NEET-PG Practice Questions and MCQs
Question 491: In which condition is retinal astrocytoma commonly seen?
- A. Tuberous sclerosis (Correct Answer)
- B. Sturge weber syndrome
- C. Von Hippel-Lindau syndrome
- D. Neurofibromatosis
Explanation: ***Tuberous sclerosis*** - **Retinal astrocytoma**, also known as **retinal astrocytic hamartoma**, is a common ocular manifestation of **tuberous sclerosis complex (TSC)** [1]. - These lesions can appear as **mulberry-like nodules** or flat, whitish patches on the retina. - Found in approximately **40-50% of patients** with tuberous sclerosis. *Sturge weber syndrome* - Characterized by a **port-wine stain (facial nevus flammeus)**, **leptomeningeal angioma**, and **glaucoma**. - Ocular manifestations include **choroidal hemangiomas** and increased episcleral venous pressure. - Does not typically involve **retinal astrocytomas**. *Von Hippel-Lindau syndrome* - Associated with **retinal capillary hemangioblastomas** (vascular tumors) and various tumors in other organs like the kidneys, pancreas, and brain. - This condition involves **vascular tumors** in the retina, not astrocytic tumors. - Important differential as it also presents with retinal lesions. *Neurofibromatosis* - A neurocutaneous syndrome characterized by **café-au-lait spots**, **neurofibromas**, and **Lisch nodules** (iris hamartomas). - Ocular manifestations include **optic nerve gliomas** and iris hamartomas, but **not retinal astrocytomas**. - NF-1 is the most common neurocutaneous syndrome but has different retinal pathology. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1318-1319.
Question 492: ER positive status in carcinoma breast indicates?
- A. Prognosis (Correct Answer)
- B. Etiology
- C. Site
- D. None of the options
Explanation: ***Prognosis*** - **ER positive status** in breast cancer indicates a better prognosis, as these tumors often respond well to hormone therapy [1][2]. - Patients with **ER positive** breast cancer usually have a lower risk of metastasis compared to **ER negative** tumors, making the outcome more favorable [1]. *Site* - ER status does not provide information regarding the **anatomical location** of the breast cancer, as it can be present in different sites of the breast. - It primarily focuses on the **biologic characteristics** of the tumor rather than its site of occurrence [1]. *None* - Selecting 'None' suggests that ER positive status has no relevance, which is incorrect as it is significant for treatment and prognosis [1]. - It is a crucial indicator for deciding on **endocrine therapy**, impacting management strategies in breast cancer patients [1]. *Etiology* - ER positive status does not directly indicate the **cause** of breast cancer, as various genetic and environmental factors contribute to its development. - It mainly reflects tumor behavior and response to therapies, not the **underlying factors** that lead to the disease [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Breast, p. 1056. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Breast, pp. 1064-1066.
Question 493: Which gene mutation is commonly associated with malignant melanoma?
- A. MYCN
- B. CDKN2A (Correct Answer)
- C. RET
- D. BRAF
Explanation: ***CDK2A*** - CDK2A mutations are implicated in malignant melanoma as they disrupt the **cell cycle regulation**, contributing to uncontrolled cell growth [1]. - Loss of CDK2A function leads to reduced **p16INK4A**, a crucial inhibitor of cyclin-dependent kinases involved in **G1/S phase transition** [1,3]. - Germline mutations of p16 (CDKN2A) are present in 25% of melanoma-prone kindreds [2], and germline mutations in CDKN2A are associated with familial forms of melanoma [3]. *RET* - RET mutations are primarily associated with **medullary thyroid carcinoma** and **multiple endocrine neoplasia type 2**, not melanoma. - It is involved in the signaling pathways but does not have a direct link to melanoma pathogenesis. *None* - Suggesting "none" misrepresents the reality that specific mutations do occur in malignant melanoma, including **CDK2A** and **BRAF**. - This option fails to recognize the importance of genetic alterations in cancer development and progression. *N-myc* - N-myc mutations are primarily associated with **neuroblastoma** and not typically linked to malignant melanoma. - In melanoma, mutations of this gene do not play a significant role in its pathophysiology compared to another tumor suppressor gene like **CDK2A**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, pp. 1150-1151. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 297-298. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 305-306.
Pharmacology
5 questionsWhich of the following drugs does not inhibit bacterial protein synthesis?
What is the mechanism of action of quinolones?
Which of the following potassium-sparing diuretics was the first to be shown to reduce cardiac mortality in chronic heart failure patients?
Which medication is commonly used in heart failure that also has aldosterone antagonistic properties?
Which of the following drugs acts directly to induce an erection without the need for sexual stimulation?
NEET-PG 2012 - Pharmacology NEET-PG Practice Questions and MCQs
Question 491: Which of the following drugs does not inhibit bacterial protein synthesis?
- A. Aminoglycosides
- B. Chloramphenicol
- C. Clindamycin
- D. Sulfonamides (Correct Answer)
Explanation: ***Sulfonamides*** - Sulfonamides do **NOT** inhibit bacterial protein synthesis; instead, they inhibit **folic acid synthesis**. - They act as **competitive inhibitors** of dihydropteroate synthase, an enzyme involved in the synthesis of dihydrofolic acid. - Folic acid is essential for nucleotide synthesis and DNA replication, making sulfonamides bacteriostatic agents that work through a completely different mechanism than protein synthesis inhibitors. *Aminoglycosides* - Aminoglycosides bind to the **30S ribosomal subunit**, causing misreading of mRNA and premature termination of protein synthesis. - This leads to the production of **abnormal and non-functional proteins**, ultimately killing the bacterial cell. *Chloramphenicol* - Chloramphenicol binds to the **50S ribosomal subunit**, thereby inhibiting the peptidyl transferase enzyme. - This prevents the formation of **peptide bonds** between amino acids, effectively blocking protein elongation. *Clindamycin* - Clindamycin also binds to the **50S ribosomal subunit**, specifically at the P-site. - It interferes with the **translocation step** of protein synthesis, preventing ribosomal movement along the mRNA.
Question 492: What is the mechanism of action of quinolones?
- A. Inhibit tetrahydrofolate reductase
- B. Inhibit DNA gyrase (Correct Answer)
- C. Bind to 30S ribosomal subunit
- D. Bind to bacterial cell membrane
Explanation: ***Inhibit DNA gyrase*** - Quinolones, particularly **fluoroquinolones**, exert their bactericidal effect by targeting **bacterial DNA gyrase (topoisomerase II)** and **topoisomerase IV**. - This inhibition prevents the uncoiling and replication of bacterial DNA, leading to cell death. *Bind to 30S ribosomal subunit* - This mechanism is characteristic of **aminoglycosides** and **tetracyclines**, which disrupt bacterial protein synthesis. - Quinolones do not interfere with ribosomal function but rather with **DNA replication**. *Bind to bacterial cell membrane* - This is the mechanism of action for **polymyxins** and **daptomycin**, which disrupt the integrity of the bacterial cell membrane. - Quinolones specifically target **intracellular enzymes** involved in DNA handling. *Inhibit tetrahydrofolate reductase* - This enzyme name in the option is technically imprecise; **trimethoprim** actually inhibits **dihydrofolate reductase**, which is part of the **sulfonamide-trimethoprim (Bactrim)** combination. - This pathway is involved in **folic acid synthesis**, crucial for bacterial DNA and RNA production, a mechanism distinct from quinolones.
Question 493: Which of the following potassium-sparing diuretics was the first to be shown to reduce cardiac mortality in chronic heart failure patients?
- A. Spironolactone (Correct Answer)
- B. Amiloride
- C. Triamterene
- D. Eplerenone
Explanation: ***Spironolactone*** - **Spironolactone** was the first potassium-sparing diuretic shown to reduce **cardiac mortality** in patients with **chronic heart failure** in the **RALES trial** (Randomized Aldactone Evaluation Study). - Its beneficial effects in heart failure are primarily attributed to its **aldosterone receptor antagonist** properties, which counteract the harmful effects of aldosterone on the myocardium and vasculature, rather than just its diuretic effect. *Amiloride* - **Amiloride** is a potassium-sparing diuretic that works by directly inhibiting **epithelial sodium channels (ENaC)** in the collecting duct. - While it helps in potassium conservation, it has not been shown to significantly reduce cardiac mortality in chronic heart failure patients in clinical trials. *Triamterene* - **Triamterene** is another potassium-sparing diuretic that also directly inhibits **ENaC** in the collecting duct, similar to amiloride. - Like amiloride, it is used to prevent hypokalemia but lacks evidence for significant **cardiac mortality reduction** in chronic heart failure. *Eplerenone* - **Eplerenone** is a selective **aldosterone receptor antagonist**, similar to spironolactone, with fewer hormonal side effects. - While it has been shown to reduce **cardiac mortality** in chronic heart failure (e.g., in the EMPHASIS-HF trial), it was introduced later than spironolactone and was not the *first* to demonstrate this benefit.
Question 494: Which medication is commonly used in heart failure that also has aldosterone antagonistic properties?
- A. Carvedilol
- B. Spironolactone (Correct Answer)
- C. Abiraterone
- D. Sacubitril/Valsartan
Explanation: ***Spironolactone*** - **Spironolactone** is a **potassium-sparing diuretic** that acts as a **competitive antagonist of aldosterone** receptors, primarily in the collecting ducts of the kidneys. - This action leads to increased excretion of sodium and water, and retention of potassium, which is beneficial in **heart failure** by reducing fluid overload and mitigating the detrimental effects of aldosterone on cardiac remodeling. *Carvedilol* - **Carvedilol** is a **beta-blocker** with additional **alpha-1 blocking** properties, commonly used in heart failure to reduce heart rate, blood pressure, and myocardial oxygen demand. - It does not possess significant aldosterone antagonistic properties. *Sacubitril/Valsartan* - **Sacubitril/Valsartan** is an **angiotensin receptor-neprilysin inhibitor (ARNI)**. Valsartan is an **angiotensin receptor blocker (ARB)**, and sacubitril inhibits neprilysin, an enzyme that degrades natriuretic peptides. - While it modulates the **renin-angiotensin-aldosterone system (RAAS)** and is highly effective in heart failure, it does not directly antagonize aldosterone receptors. *Abiraterone* - **Abiraterone** is an **androgen-biosynthesis inhibitor** used in the treatment of **prostate cancer**. - Its primary mechanism involves inhibiting **CYP17**, an enzyme critical for androgen production, and it has no role in the management of heart failure or aldosterone antagonism.
Question 495: Which of the following drugs acts directly to induce an erection without the need for sexual stimulation?
- A. Sildenafil
- B. Tadalafil
- C. Alprostadil (Correct Answer)
- D. Testosterone
Explanation: ***Alprostadil***- **Alprostadil** is a **prostaglandin E1** analog that can directly induce vasodilation in the penile arteries, leading to an erection without sexual stimulation [1].- It is typically administered via **intracavernosal injection** or as a **urethral suppository**.*Sildenafil*- **Sildenafil** is a **PDE5 inhibitor** that works by enhancing the effects of **nitric oxide**, which is released in response to sexual stimulation [2, 3].- It requires **sexual arousal** to be effective, as it doesn't directly initiate the erectile process [2, 3].*Tadalafil*- Similar to sildenafil, **tadalafil** is also a **PDE5 inhibitor** that works by increasing cGMP levels and promoting smooth muscle relaxation [2, 3].- Its action is dependent on the release of **nitric oxide** triggered by sexual stimulation [2, 3].*Testosterone*- **Testosterone** is a hormone involved in sex drive and overall erectile function over time, but it does not directly or acutely induce an erection.- Its primary role in erectile dysfunction is in cases of **hypogonadism**, and it requires sexual stimulation for its effects on erection.