Biochemistry
3 questionsProtein segregation occurs in which organelle?
Which of the following statements about the inheritance of an X-linked recessive trait is true?
What is the most sensitive biochemical marker for a 7-day old myocardial infarction?
NEET-PG 2012 - Biochemistry NEET-PG Practice Questions and MCQs
Question 341: Protein segregation occurs in which organelle?
- A. Peroxisomes
- B. ER
- C. Mitochondria
- D. Golgi apparatus (Correct Answer)
Explanation: ***Golgi apparatus*** - The **Golgi apparatus** is a central organelle for **protein modification, sorting, and packaging** into vesicles for delivery to various cellular destinations. - It acts as a "post office" of the cell, directing proteins to their correct locations through **segregation** into specific secretory or transport pathways. *Peroxisomes* - **Peroxisomes** are involved in **metabolic processes** such as fatty acid oxidation and detoxification. - While they import some proteins, their primary role is not in the overall **segregation** and trafficking of proteins for diverse cellular destinations. *ER* - The **endoplasmic reticulum (ER)** is where proteins are synthesized (rough ER) and undergo initial folding and modification, including glycosylation. - However, the ER's main function is protein synthesis and early modification, not the final **segregation** and sorting for transport to different cellular locations. *Mitochondria* - **Mitochondria** are primarily responsible for **ATP production** through cellular respiration and houses its own genome. - While mitochondria import specific proteins necessary for their function, they are not involved in the general **segregation** of proteins destined for other organelles or secretion.
Question 342: Which of the following statements about the inheritance of an X-linked recessive trait is true?
- A. Fathers can transmit X-linked traits to their sons
- B. 25% of sons of a carrier mother are affected
- C. Carrier mothers have a 50% chance of transmitting the disease to their sons (Correct Answer)
- D. 100% of daughters of a diseased father are affected
Explanation: ***Carrier mothers have a 50% chance of transmitting the disease to their sons*** - A mother who is a carrier for an **X-linked recessive trait** has one normal X chromosome and one X chromosome carrying the recessive allele. - Each son she has has a **50% chance** of inheriting the X chromosome with the recessive allele (and thus being affected) and a 50% chance of inheriting the normal X chromosome. *Fathers can transmit X-linked traits to their sons* - Fathers transmit their **Y chromosome** to their sons, not an X chromosome. - Therefore, fathers cannot directly transmit X-linked traits to their sons. *25% of sons of a carrier mother are affected* - This statement is incorrect; as explained above, a carrier mother has a **50% chance** of transmitting the affected X chromosome to each son. - The 25% probability typically applies to autosomal recessive inheritance, not X-linked. *100% of daughters of a diseased father are affected* - A diseased father (meaning he has the **X-linked recessive trait**) will pass his single X chromosome to all of his daughters. - Therefore, all his daughters will be **obligate carriers**, but they will only be affected if their mother also contributes an X chromosome with the recessive allele (which is rare for recessive traits).
Question 343: What is the most sensitive biochemical marker for a 7-day old myocardial infarction?
- A. CPK MB
- B. LDH
- C. Myoglobin
- D. Troponin I/T (Correct Answer)
Explanation: ***Troponin I/T*** - **Cardiac troponins (I and T)** are highly sensitive and specific biomarkers for **myocardial injury**. - While they rise quickly after an MI, they also remain elevated for an extended period, typically **7 to 10-14 days**, making them ideal for detecting a 7-day-old event. *CPK MB* - **Creatine phosphokinase MB (CPK-MB)** is a well-known cardiac marker, but its elevation is more transient, usually returning to normal within **2-3 days** post-MI. - Therefore, it would likely be undetectable or near baseline 7 days after the event, making it insensitive for this duration. *LDH* - **Lactate dehydrogenase (LDH)** used to be used as a cardiac marker, but it is **non-specific** and found in various tissues. - While it can remain elevated for an extended period after an MI (up to 10-14 days), its lack of specificity makes other markers, particularly troponins, much more reliable for confirming myocardial damage. *Myoglobin* - **Myoglobin** is one of the earliest markers to rise after myocardial injury, but it is also **rapidly cleared** from the bloodstream, usually within 24 hours. - Due to its short half-life, myoglobin would not be elevated 7 days after an MI, making it unsuitable for detecting such a remote event.
Internal Medicine
2 questionsWhich condition is most commonly associated with systemic amyloidosis?
What is the term for the collapse of a lung?
NEET-PG 2012 - Internal Medicine NEET-PG Practice Questions and MCQs
Question 341: Which condition is most commonly associated with systemic amyloidosis?
- A. Chronic Kidney Disease (Correct Answer)
- B. Multiple Myeloma
- C. Rheumatoid Arthritis
- D. Familial Mediterranean Fever
Explanation: Type II DM - Amyloidosis is commonly associated with **chronic diseases** like type II diabetes mellitus due to insulin resistance leading to amyloid deposition [4]. - The presence of **amiloid in the pancreas** often correlates with the complications of this type of diabetes [3]. *Maturity onset DM* - While maturity-onset diabetes can lead to complications, it is often synonymous with **type II DM**, making this distinction inaccurate regarding amyloidosis. - This term is less commonly used and does not emphasize the direct link to amyloidosis seen in type II diabetes. *HTN* - Hypertension itself is not a direct cause of amyloidosis; it typically results from other underlying conditions. - The association of amyloidosis with hypertension is usually **secondary**, not a primary condition leading to amyloid deposits [2]. *Type I DM* - Type I diabetes is primarily **autoimmune**, resulting in insulin-deficient states and does not strongly associate with amyloidosis like type II [1]. - The amyloid deposits seen in type I are much less common compared to type II or associated chronic conditions.
Question 342: What is the term for the collapse of a lung?
- A. Emphysema
- B. Atelectasis (Correct Answer)
- C. Bronchitis
- D. Bronchiectasis
Explanation: ***Atelectasis*** - **Atelectasis** is the technical term for the **collapse of a lung** or a part of a lung, leading to reduced or absent gas exchange. - It can be caused by **obstruction of the airway** (e.g., mucus plug, foreign body) or external compression on the lung [1]. *Emphysema* - **Emphysema** is a chronic lung disease characterized by the **destruction of the alveoli**, leading to permanent enlargement of airspaces [2]. - It results in reduced elastic recoil of the lungs and is a type of **COPD (chronic obstructive pulmonary disease)** [2]. *Bronchiectasis* - **Bronchiectasis** is a chronic condition where the airways (bronchi) become **abnormally widened** and scarred. - This widening leads to a buildup of mucus, making the lungs vulnerable to **recurrent infections**. *Bronchitis* - **Bronchitis** is an inflammation of the lining of the bronchial tubes, which carry air to and from your lungs. - It typically causes a **cough** with mucus production and can be acute or chronic.
Pathology
4 questionsWhich of the following statements about desmoid tumors is incorrect?
Which tumor marker is most commonly associated with lung and breast carcinoma?
Vegetations in Libman-Sacks endocarditis are:
Medial calcification is seen in -
NEET-PG 2012 - Pathology NEET-PG Practice Questions and MCQs
Question 341: Which of the following statements about desmoid tumors is incorrect?
- A. Show infiltrative growth pattern
- B. Often seen below the umbilicus
- C. More common in women
- D. Highly radiosensitive (Correct Answer)
Explanation: ***Highly radiosensitive*** - This is the **INCORRECT** statement and hence the correct answer to this question. - Desmoid tumors are **radioresistant**, not radiosensitive, meaning they do not respond well to radiation therapy. - Radiation therapy is typically reserved for cases where surgery is not feasible or for local control after incomplete resection, but it is not highly effective as a standalone treatment. - The radioresistant nature is an important clinical characteristic that influences treatment planning. *Often seen below the umbilicus* - This statement is **correct** about desmoid tumors. - Desmoid tumors frequently arise from the **anterior abdominal wall**, with a common location being below the umbilicus, particularly in postpartum women. - Abdominal wall desmoids are strongly associated with **pregnancy** and trauma, and can be locally aggressive. *Show infiltrative growth pattern* - This statement is **correct** about desmoid tumors. [1] - Desmoid tumors are characterized by their **locally aggressive** and infiltrative growth pattern, often invading adjacent tissues like muscle, fascia, and neurovascular structures. [1] - This infiltrative nature makes complete surgical resection challenging and contributes to a high rate of **local recurrence** (up to 20-40% after surgery). - Despite their aggressive local behavior, desmoid tumors do not metastasize. *More common in women* - This statement is **correct** about desmoid tumors. - Desmoid tumors show a **female predominance**, particularly affecting women during their reproductive years (ages 25-40). - This gender predilection is linked to **hormonal influences**, with increased risk during **pregnancy** and the postpartum period. - The association with estrogen is further supported by occasional tumor regression after menopause. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 691-692.
Question 342: Which tumor marker is most commonly associated with lung and breast carcinoma?
- A. CEA (Correct Answer)
- B. hCG
- C. AFP
- D. CA-15-3
Explanation: ***CEA*** - **Carcinoembryonic antigen (CEA)** is a tumor marker commonly associated with **lung** and **breast cancers** [1]. - Elevated levels of CEA are often observed in **various malignancies**, making it useful for monitoring treatment response and recurrence. *CA-15-3* - While **CA-15-3** is a breast cancer marker, it is less specific than CEA and often used primarily for **monitoring** but not for initial diagnosis. - It is primarily elevated in **breast carcinoma**, not typically associated with **lung cancer**. *11CG* - This ppears to be incorrectly referenced and may not exist as a recognized tumor marker for lung or breast cancer. - There are no clinical associations with lung or breast cancer, making it irrelevant in this context. *AFP* - **Alpha-fetoprotein (AFP)** is primarily associated with **liver** and **germ cell tumors**, not commonly associated with lung or breast cancers [1]. - Elevated AFP levels do not correlate with lung or breast carcinomas, distinguishing it from CEA's relevance. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, p. 346.
Question 343: Vegetations in Libman-Sacks endocarditis are:
- A. Large and fragile
- B. Small warty along the line of closure of valve
- C. Small or medium sized on either or both sides of valve (Correct Answer)
- D. Small bland vegetations
Explanation: ***Small or medium sized on either or both sides of valve*** - **Libman-Sacks endocarditis** typically presents with vegetations that are **small to medium in size**, found on either aspect of the valve leaflets [1][2][3]. - These vegetations are **sterile**, non-infectious, and often associated with systemic lupus erythematosus (SLE) [2][3]. *Large and fragile* - Vegetations in Libman-Sacks endocarditis are not typically **large**; they are small or medium [1]. - The term **fragile** is misleading, as the vegetations are not characterized by fragility but by being sturdy yet non-infectious. *Small warty along the line of closure of valve* - While the vegetations are small, they are **not warty** and do not primarily form along the line of closure, which is common in infective endocarditis [1]. - Libman-Sacks vegetations can be found on either side of the valve, unlike warty vegetations [1]. *Small bland vegetations* - Vegetations in Libman-Sacks endocarditis are bland but not solely described as **small and bland**; their presence on either or both sides of the valve is critical [1]. - This option fails to capture the significance of their size and localization in the endocardial lesions associated with SLE. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, p. 568. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 232-233. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, p. 570.
Question 344: Medial calcification is seen in -
- A. Atherosclerosis
- B. Arteriolosclerosis
- C. Dissecting aneurysm
- D. Monckeberg's sclerosis (Correct Answer)
Explanation: ***Monckeberg's sclerosis*** - This condition is characterized by **calcific deposits** within the **tunica media** of muscular arteries. - It typically does not occlude the vessel lumen and is often asymptomatic, though severe calcification can lead to vessel rigidity. *Atherosclerosis* - Involves the formation of **atheromatous plaques** in the **tunica intima** of large and medium-sized arteries. - These plaques consist of lipids, inflammatory cells, smooth muscle cells, and fibrous connective tissue, leading to luminal narrowing and hardening of arteries. *Arteriolosclerosis* - Refers to the thickening and hardening of the walls of **arterioles** (small arteries). - It is often associated with hypertension and diabetes, affecting resistance vessels but typically not involving extensive medial calcification. *Dissecting aneurysm* - This condition involves a **tear in the tunica intima** of an artery, allowing blood to enter and dissect between the layers of the arterial wall. - It is a life-threatening condition primarily affecting the aorta and is characterized by a false lumen, not medial calcification.
Physiology
1 questionsCells most sensitive to hypoxia are?
NEET-PG 2012 - Physiology NEET-PG Practice Questions and MCQs
Question 341: Cells most sensitive to hypoxia are?
- A. Myocardial cells
- B. Neurons (Correct Answer)
- C. Hepatocytes
- D. Renal tubular epithelial cells
Explanation: ***Neurons*** - Neurons have a very high metabolic rate and an **absolute requirement for oxygen** and glucose to maintain their complex electrochemical functions and ionic gradients. - Due to their lack of significant energy reserves and high metabolic demand, they can sustain **irreversible damage within minutes** (typically 3-5 minutes) of complete oxygen deprivation. *Myocardial cells* - While myocardial cells are highly susceptible to hypoxia and can undergo **ischemic necrosis** (e.g., in a myocardial infarction), they can often tolerate oxygen deprivation for somewhat longer periods than neurons due to some anaerobic metabolic capacity. - Significant damage to myocardial cells usually occurs after **20-30 minutes of severe ischemia**. *Hepatocytes* - Hepatocytes (liver cells) are relatively **resilient to hypoxia** compared to neurons, possessing significant metabolic flexibility and capacity for regeneration. - They can endure **longer periods of oxygen deprivation** before irreversible damage occurs, often hours. *Renal tubular epithelial cells* - Renal tubular epithelial cells are generally **sensitive to hypoxia**, especially those in the medulla, due to their high metabolic activity for reabsorption and secretion. - They are a common target for **acute tubular necrosis** in ischemic injury but generally have a **higher tolerance than neurons**, with damage becoming widespread after tens of minutes to an hour of severe ischemia.