NEET-PG 2012 Practice Questions

Q: Nucleus gracilis and nucleus cuneatus are seen in?

Medulla. ***Medulla*** - The **nucleus gracilis** and **nucleus cuneatus** are located in the **dorsal medulla** and are crucial for processing **conscious proprioception**, **vibration**, and **fine touch**. - These nuclei receive input from the fasciculus gracilis and fasciculus cuneatus (dorsal column tracts) and are part of the dorsal column-medial lemniscus pathway. - They give rise to the **internal arcuate fibers** which decussate and form the **medial lemniscus**. *Pons* - The pons contains several important nuclei, including the **pontine nuclei** (involved in motor coordination), nuclei of cranial nerves V, VI, VII, and VIII, and the **locus coeruleus**. - The dorsal column nuclei are not located in the pons. *Temporal lobe* - The **temporal lobe** is part of the cerebral cortex and is primarily involved in **auditory processing**, memory formation, and language comprehension. - It contains structures like the hippocampus and amygdala, but not the dorsal column nuclei. *Midbrain* - The **midbrain** contains nuclei such as the **red nucleus**, **substantia nigra**, and nuclei of cranial nerves III and IV, involved in motor control and eye movements. - The nucleus gracilis and nucleus cuneatus are not found in the midbrain.

Q: Which macronutrient has the highest thermogenic effect?

Proteins. ***Proteins*** - Proteins have the **highest thermogenic effect** (also known as the **thermic effect of food** or TEF) among macronutrients, typically ranging from **20-30%** of their caloric content. - This high TEF is due to the energy required for their **digestion**, **absorption**, and **metabolism** (e.g., deamination, protein synthesis), making them more metabolically "expensive" to process than fats or carbohydrates. *Fat* - Fat has the **lowest thermogenic effect**, accounting for approximately **0-3%** of its caloric content. - This low TEF is because fats are **easily absorbed** and stored, requiring minimal energy for their processing. *Carbohydrate* - Carbohydrates have an intermediate thermogenic effect, typically ranging from **5-10%** of their caloric content. - The energy expenditure for carbohydrate metabolism involves processes like **digestion**, **absorption**, and **glucose oxidation** or conversion to glycogen. *Alcohol* - While alcohol has a relatively high thermogenic effect (**20-25%**), it is **not classified as a macronutrient** in traditional nutritional science. - The three primary macronutrients are proteins, carbohydrates, and fats. Among these, **proteins** have the highest TEF.

Q: Which of the following is an ω-6 fatty acid?

Linoleic acid. ***Linoleic acid*** - **Linoleic acid** (LA), an 18-carbon fatty acid with two double bonds (18:2), is classified as an **ω-6 fatty acid** because its first double bond is located at the sixth carbon atom from the methyl end of the fatty acid chain. - It is an **essential fatty acid** that must be obtained through diet, serving as a precursor for other ω-6 fatty acids like arachidonic acid. *Cervonic acid* - **Cervonic acid** is another name for **docosahexaenoic acid (DHA)**, which is an **ω-3 fatty acid** (22:6). - Its first double bond is located at the third carbon from the methyl end. *Alpha linolenic acid* - **Alpha-linolenic acid** (ALA) is an **ω-3 fatty acid** (18:3). - Its first double bond is located at the third carbon atom from the methyl end. *Elaidic acid* - **Elaidic acid** is a **trans fatty acid** (18:1 trans-9). - It is classified as an **ω-9 fatty acid** due to the position of its double bond, but its trans configuration is the primary distinguishing feature.

Q: What is the cofactor required for the enzyme xanthine oxidase?

Molybdenum. ***Molybdenum*** - **Xanthine oxidase** is a key enzyme in **purine metabolism**, responsible for the oxidation of **hypoxanthine to xanthine** and further to **uric acid**. - **Molybdenum** is an essential trace element that serves as a **cofactor** for several enzymes, including xanthine oxidase, where it helps facilitate electron transfer reactions. *Selenium* - **Selenium** is a cofactor for **glutathione peroxidase**, an enzyme involved in antioxidant defense. - It is not directly involved in the function of **xanthine oxidase**. *Zinc* - **Zinc** is a cofactor for a wide range of enzymes, including **carbonic anhydrase** and **alcohol dehydrogenase**. - It does not serve as a cofactor for **xanthine oxidase**. *Magnesium* - **Magnesium** is a critical cofactor for many enzymes, particularly those involved in **ATP hydrolysis and synthesis** and **DNA/RNA synthesis**. - It is not a cofactor for **xanthine oxidase**.

Q: Which amino acid among the following has significant UV absorption at 280 nm used in protein quantification?

Tyrosine. ***Correct Option: Tyrosine*** - Tyrosine contains a **phenol functional group** (aromatic ring with hydroxyl group), giving it **significant UV absorption at 280 nm** (specifically ~274 nm) - Along with **tryptophan** and **phenylalanine**, tyrosine is one of the three aromatic amino acids used for **protein quantification via UV spectroscopy** - The aromatic side chain with conjugated double bonds enables strong UV light absorption *Incorrect Option: Alanine* - Alanine has a **methyl group** as its side chain (non-polar, aliphatic) - **Lacks aromatic rings** or conjugated systems - Does **not absorb UV light** at 280 nm *Incorrect Option: Histidine* - Histidine has an **imidazole ring** (heterocyclic aromatic) in its side chain - While technically aromatic, it has **minimal UV absorption at 280 nm** (weak absorption around 210-230 nm) - **Not used for protein quantification** at 280 nm due to insignificant absorption at this wavelength *Incorrect Option: Arginine* - Arginine contains a **guanidinium group** (highly basic, polar) - **Non-aromatic structure** without conjugated double bonds - Does **not exhibit UV absorption** at wavelengths used for protein analysis

Q: What is the chromosomal translocation associated with Acute Myeloid Leukemia M3?

t(15;17). ***T (15,17)*** [1][2][3] - This translocation pertains to **Acute Promyelocytic Leukemia (APL)**, associated with the fusion gene **PML-RARA** [1][3]. - APL is characterized by **promyelocytes** with heavy granulation and a clinical presentation that includes coagulopathy [2][3]. *T (8, 21)* - This translocation is associated with **AML M2**, involving the **RUNX1-RUNX1T1** fusion gene [3]. - It does not correlate with the classic features of AML M3, which is specifically characterized by T (15,17). *T (9,11)* - Primarily seen in **AML M5**, this translocation is not related to the pathophysiology of AML M3. - The fusion commonly observed here is **MLL-AFF1**, which affects different types of leukemias, not APL. *T (18,21)* - This translocation does not have a significant association with any specific type of acute myeloid leukemia. - Unlike T (15,17), it is not linked to the classic features or unique clinical presentation seen in AML M3. **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, pp. 620-621. [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. 621-622. [3] 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. 620.

Q: Which of the following is NOT a pathological manifestation of chronic alcoholism?

Piecemeal necrosis. ***Piecemeal necrosis*** - Piecemeal necrosis is not a common manifestation of chronic alcoholism but is instead more typical of **autoimmune hepatitis** or **chronic viral hepatitis**. - Chronic alcoholism primarily leads to different types of liver damage, such as **steatosis** or **apoptosis**, rather than piecemeal necrosis. *Balloning degeneration* - Balloning degeneration reflects **swelling** of hepatocytes, often associated with **alcoholic liver disease** and represents liver cell injury [1]. - It is a recognized feature seen in chronic alcohol exposure indicating the effect of toxicity on liver cells [1]. *Microvesicular fatty changes* - Microvesicular fatty changes, characterized by small fat vacuoles in liver cells, can be induced by chronic alcohol use and is commonly noted in **steatosis** [2]. - This finding is also seen in conditions like **reye syndrome** and is closely related to alcohol-induced liver injury. *Central hyaline sclerosis* - Central hyaline sclerosis refers to fibrosis and is often related to chronic liver disease but is not a direct pathological manifestation seen in chronic alcoholism. - However, chronic alcohol abuse contributes to **cirrhosis**, which can lead to various forms of liver scarring, but this is not specific to alcohol alone [3]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 389-390. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Liver and Gallbladder, pp. 848-850. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Liver and Gallbladder, p. 848.

Q: All of the following statements about Giant cell arteritis are true except?

Involves large to small sized arteries. ***Involves large to small sized arteries*** - Giant cell arteritis (GCA) predominantly affects **medium to large-sized arteries**, most commonly the branches of the **carotid artery**, such as the temporal arteries [1]. - While it can affect various arteries, it does not typically involve **small-sized arteries**, such as arterioles, directly as a primary site of inflammation. *Granulomatous inflammation* - GCA is characterized histologically by **granulomatous inflammation** within the arterial wall, which includes multinucleated **giant cells** and lymphocytes [2]. - This specific inflammatory pattern is a hallmark feature used in the diagnosis of GCA upon biopsy [2]. *Segmental nature of the involvement* - The arterial inflammation in GCA is often **segmental**, meaning that affected arteries may have inflamed and non-inflamed sections alternating along their length [2]. - This segmental involvement often necessitates **longer biopsies** (e.g., 2-3 cm for temporal artery biopsy) to increase the diagnostic yield. *Can involve the aorta and its major branches* - GCA can indeed affect the **aorta** (aortitis) and its major branches, leading to complications like **aneurysms** or **dissections**. - Involvement of these larger vessels can manifest as symptoms such as **claudication** in the limbs or asymptomatic aneurysms detectable on imaging [1]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 688-689. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 516-517.

Q: Gas exchange in tissues takes place at?

Capillary. ***Capillary*** - **Capillaries** are the smallest and most numerous blood vessels, with very thin walls (only one cell thick), which facilitates the efficient exchange of gases, nutrients, and waste products between blood and tissues. - Their extensive network ensures close proximity to nearly every cell in the body, maximizing the surface area and minimizing the diffusion distance for **gas exchange**. *Artery* - Arteries carry **oxygenated blood** away from the heart to the tissues but have thick, muscular walls designed for high pressure and transport, not for direct exchange with tissues. - They branch into smaller arterioles, which then lead to capillaries, making them a conduit rather than an exchange site. *Vein* - Veins carry **deoxygenated blood** back to the heart from the tissues and have relatively thin walls compared to arteries but are still too thick for efficient gas exchange. - They primarily serve as blood return vessels and reservoirs. *Venules* - Venules are small blood vessels that merge from capillaries and eventually combine to form veins; they primarily function in collecting blood from capillary beds. - While slightly more permeable than larger veins, their main role is still collection and transport, not the extensive gas exchange facilitated by capillaries.

Q: Which of the following is the MOST accurate statement about CSF?

Formed by the choroid plexus in the ventricles.. ***Formed by the choroid plexus in the ventricles.*** * The **choroid plexus**, located in the ventricles of the brain, is primarily responsible for the production of **cerebrospinal fluid (CSF)**. * Specialized epithelial cells of the choroid plexus filter blood plasma to produce CSF, which then circulates through the central nervous system. *Normally contains no neutrophils* * Normal CSF should contain **virtually no neutrophils**; their presence typically indicates an inflammatory or infectious process, such as **bacterial meningitis**. * While normal CSF doesn't have neutrophils, this option isn't as broadly accurate as the choroid plexus statement because the presence of other cell types like lymphocytes in small numbers is normal. *pH is less than that of plasma* * The pH of CSF is typically **slightly lower than that of plasma** (around 7.31 compared to 7.40), but the statement "less than" is broad and the degree of difference can be variable and is a less defining characteristic than its formation site. * This slight difference in pH is important for regulating **respiration** through chemoreceptors, but it's not the most accurate or fundamental statement about CSF properties. *Removal of CSF during dural tap can cause a headache due to the change in pressure.* * A **post-dural puncture headache** (PDPH) is a well-known complication of a dural tap (lumbar puncture), caused by the leakage of CSF from the puncture site, leading to **intracranial hypotension**, not simply a change in pressure. * This decrease in CSF volume and pressure causes a traction on pain-sensitive structures within the cranium, resulting in a headache that is typically **worse when upright** and relieved by lying down.

Question 1

Nucleus gracilis and nucleus cuneatus are seen in?

Accepted Answer

Medulla

Answer

Temporal lobe

Answer

Midbrain

Answer

Pons

Question 2

Which macronutrient has the highest thermogenic effect?

Accepted Answer

Proteins

Answer

Fat

Answer

Carbohydrate

Answer

Alcohol

Question 3

Which of the following is an ω-6 fatty acid?

Accepted Answer

Linoleic acid

Answer

Cervonic acid

Answer

Alpha linolenic acid

Answer

Elaidic acid

Question 4

What is the cofactor required for the enzyme xanthine oxidase?

Accepted Answer

Molybdenum

Answer

Selenium

Answer

Zinc

Answer

Magnesium

Question 5

Which amino acid among the following has significant UV absorption at 280 nm used in protein quantification?

Accepted Answer

Tyrosine

Answer

Alanine

Answer

Histidine

Answer

Arginine

Question 6

What is the chromosomal translocation associated with Acute Myeloid Leukemia M3?

Accepted Answer

t(15;17)

Answer

t(18;21)

Answer

t(9;11)

Answer

t(8;21)

Question 7

Which of the following is NOT a pathological manifestation of chronic alcoholism?

Accepted Answer

Piecemeal necrosis

Answer

Microvesicular fatty changes

Answer

Central hyaline sclerosis

Answer

Ballooning degeneration

Question 8

All of the following statements about Giant cell arteritis are true except?

Accepted Answer

Involves large to small sized arteries

Answer

Granulomatous inflammation

Answer

Segmental nature of the involvement

Answer

Can involve the aorta and its major branches

Question 9

Gas exchange in tissues takes place at?

Accepted Answer

Capillary

Answer

Artery

Answer

Vein

Answer

Venules

Question 10

Which of the following is the MOST accurate statement about CSF?

Accepted Answer

Formed by the choroid plexus in the ventricles.

Answer

Normally contains no neutrophils

Answer

pH is less than that of plasma

Answer

Removal of CSF during dural tap can cause a headache due to the change in pressure.

NEET-PG 2012

Anatomy

Biochemistry

Pathology

Physiology