NEET-PG 2012 Practice Questions

Q: Pituicytes are seen in ?

Posterior lobe. ***Posterior lobe*** - **Pituicytes** are specialized glial cells found exclusively in the **posterior pituitary** (neurohypophysis). [1] - They provide structural support and regulation for the nerve terminals that release **antidiuretic hormone (ADH)** and **oxytocin**. [1] *Anterior lobe* - The anterior pituitary, or **adenohypophysis**, consists of glandular epithelial cells that synthesize and secrete various hormones. [2] - It does not contain pituicytes, which are glial cells. [2] *Intermediate lobe* - The intermediate lobe is a rudimentary part of the pituitary gland in humans, primarily producing **melanocyte-stimulating hormone (MSH)**. [1] - While it is part of the pituitary, it does not contain pituicytes. *All of the options* - Pituicytes are specific to the posterior pituitary, so they are not found in all parts of the gland. - Different lobes of the pituitary gland have distinct cellular compositions and functions.

Q: Which of the following is NOT a surface marking of the oblique fissure of the lung?

7th rib. ***7th rib*** - The **oblique fissure** typically extends from the spine at approximately the **T3 vertebral level** anteriorly to the **6th costal cartilage**. [1] - The **7th rib** is generally inferior to the typical anterior termination point of the oblique fissure. [1] *T3* - The **oblique fissure** begins posteriorly at the level of the **spinous process of T3**. [1] - This marks the superior-posterior extent of the fissure on the surface. *5th rib* - The **oblique fissure** crosses the **5th intercostal space** on the lateral chest wall. [1] - This point helps map the fissure's path between its posterior and anterior endpoints. *6th costal cartilage* - The **oblique fissure** terminates anteriorly near the **6th costal cartilage** in the midclavicular line. [1] - This represents the inferior-anterior most point of the fissure on the chest wall.

Q: What is the primary product of fatty acid oxidation (β-oxidation)?

Acetyl CoA. ***Acetyl CoA*** - Beta-oxidation of fatty acids involves a series of reactions that cleave two-carbon units from the fatty acyl chain, forming **acetyl CoA**. - **Acetyl CoA** is the direct product of each cycle of β-oxidation and then enters the **citric acid cycle** to generate ATP or serves as a precursor for other anabolic pathways. *Malonyl CoA* - **Malonyl CoA** is a key intermediate in **fatty acid synthesis**, not degradation. - It's formed from acetyl CoA by acetyl-CoA carboxylase and acts as a substrate for **fatty acid synthase**, and also as a physiological inhibitor of carnitine palmitoyltransferase I (CPT-I), thereby regulating β-oxidation. *Ketone bodies* - **Ketone bodies** (**acetoacetate** and **β-hydroxybutyrate**) are produced from acetyl CoA in the liver during conditions of low glucose availability or prolonged fasting. - They serve as an alternative fuel source for tissues like the brain and muscles, but are secondary products derived from the condensation of acetyl CoA molecules, not the primary direct product of fatty acid breakdown itself. *Cholesterol* - **Cholesterol** is a steroid lipid synthesized from **acetyl CoA** through a complex multi-step pathway (via HMG-CoA reductase pathway). - It is an important structural component of cell membranes and a precursor for steroid hormones and bile acids, but not a direct product of fatty acid catabolism.

Q: What occurs during the stage of Grey hepatization?

Accumulation of fibrin. ***Accumulation of fibrin*** - Grey hepatization is characterized by the **presence of fibrinous exudate** in the alveoli, indicating significant lung pathology, usually in cases of pneumonia [1,2]. - This stage follows red hepatization and reflects the **progression of inflammation** within the lung tissue [1,2]. *RBC's fill the alveoli* - This occurs during the **red hepatization** stage, where RBCs invade alveoli, not grey hepatization [1,2]. - **Grey hepatization** is marked by **fibrinous deposits** instead of erythrocytes [1,2]. *Organisms fill the alveoli* - While organisms, such as bacteria, can be present, they are more characteristic of the **initial infection phase** rather than grey hepatization [1]. - This stage reflects more on the **inflammatory response** than the presence of pathogens. *WBC's fill the alveoli* - The infiltration of **WBCs (like neutrophils)** represents an earlier inflammatory process, usually preceding grey hepatization [1,2]. - In grey hepatization, the focus is on the **accumulation of fibrin**, not directly on WBC infiltration [1,2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 711-712. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 317-318.

Q: Salty taste is due to?

Sodium ion channels. ***Sodium ion channels*** - The sensation of **salty taste** is primarily mediated by the direct influx of **sodium ions (Na+)** into taste receptor cells. - This influx leads to **depolarization** of the cell membrane, triggering neurotransmitter release and signaling to the brain. *Calcium ion channels* - While calcium ions are crucial for various cellular processes, including **neurotransmitter release**, they are not the primary initiators of the salty taste transduction pathway. - Calcium channels are more directly involved in the sensation of **umami** and **sweet tastes**, often via G-protein coupled receptors. *G-protein coupled receptors* - **G-protein coupled receptors (GPCRs)** are responsible for the transduction of **sweet, bitter, and umami tastes**. - They are not involved in the direct detection of **saline compounds**, which operate through ion channels. *Proton channels* - **Proton channels (H+)** are primarily involved in the sensation of **sour taste**. - The influx of protons causes intracellular acidification, leading to cell depolarization.

Q: Which substrate is both secreted and filtered by the kidneys?

Uric Acid. ***Uric Acid*** - **Uric acid** is freely **filtered** at the glomerulus. - It undergoes both **secretion** and reabsorption in the renal tubules, making it a substrate that is both secreted and filtered. *Glucose* - **Glucose** is freely **filtered** at the glomerulus but is almost completely **reabsorbed** in the proximal tubule under normal physiological conditions. - It is not actively secreted by the renal tubules. *Urea* - **Urea** is freely **filtered** at the glomerulus. - It undergoes **reabsorption** (especially in the medullary collecting duct) and some facilitated diffusion, but significant active secretion is not its primary handling mechanism. *Na+* - **Sodium (Na+)** is freely **filtered** at the glomerulus in large quantities. - Its renal handling is dominated by extensive **reabsorption** throughout the nephron, which is crucial for fluid balance and blood pressure regulation, with no active secretion.

Q: During acclimatization to hot environments, increased sweating efficiency is primarily due to enhanced sensitivity of which receptors?

Cholinergic receptors. ***Cholinergic receptors*** - **Sweat glands** are innervated by **sympathetic postganglionic fibers** that release **acetylcholine**, acting on **muscarinic cholinergic receptors** to stimulate sweating. - During **acclimatization**, the sweat glands become more sensitive to acetylcholine, resulting in **increased sweating efficiency** and a lower threshold temperature for sweating. *Adrenergic receptors* - Adrenergic receptors are primarily involved in the sympathetic nervous system's response to **norepinephrine** and **epinephrine**, mediating effects like **vasoconstriction** and **bronchodilation**. - They are not the primary receptors responsible for stimulating **eccrine sweat gland** secretion in response to heat. *Noradrenergic receptors* - **Noradrenergic receptors** are a type of adrenergic receptor that respond to **norepinephrine** (noradrenaline). - While sympathetic activity increases in hot environments, the primary stimulation of **sweat glands** is via **acetylcholine** acting on cholinergic receptors, not noradrenergic receptors. *Dopaminergic receptors* - **Dopaminergic receptors** respond to **dopamine** and are involved in various functions including **motor control**, **reward**, and **neuroendocrine regulation**. - These receptors are not directly involved in the physiological regulation of **sweating efficiency** during heat acclimatization.

Q: What is the average progressive velocity of human sperm under standard laboratory conditions?

1-3 mm/min. ***1-3 mm/min*** - The typical average progressive velocity of human sperm, categorized as **Grade A (rapid progressive)** motility, ranges from **25 micrometers/second or faster**, which translates to approximately 1-3 mm/minute. - This velocity is crucial for sperm to traverse the female reproductive tract and reach the ovum for fertilization. *4-6 mm/min* - This velocity range is significantly faster than the **average progressive velocity** observed in viable human sperm under standard laboratory conditions. - While some individual sperm may achieve higher speeds, this range is not representative of the **average progressive motility** of a healthy sperm population. *6-9 mm/min* - This progressive velocity is exceptionally high and not typically observed as the average for human sperm, even for highly motile sperm. - Such a high velocity would indicate an **abnormally fast movement** not compatible with biological norms for average progressive motility. *10-13 mm/min* - This range represents an extremely rapid progressive velocity for human sperm, well beyond physiological averages. - It does not align with the standard measurements for **progressive motility**, which are generally much lower.

Q: Which type of carbohydrate is absorbed most efficiently from the gastrointestinal tract?

Monosaccharides. ***Monosaccharides*** - **Monosaccharides**, like glucose and fructose, are the simplest forms of carbohydrates and do not require further digestion. - They are directly absorbed into the bloodstream from the intestinal lumen via specific **transporters** on the enterocyte membrane. *Disaccharides* - **Disaccharides**, such as sucrose and lactose, must first be broken down into their constituent monosaccharides by **brush border enzymes** (e.g., lactase, sucrase) before absorption can occur. - This additional enzymatic step makes their absorption less efficient than that of monosaccharides. *Polysaccharides* - **Polysaccharides**, including starch and glycogen, are complex carbohydrates requiring extensive digestion by enzymes like **amylase** in the mouth and small intestine. - This multi-step breakdown into monosaccharides is the least efficient process and takes the longest time. *5-carbon sugars* - While 5-carbon sugars (**pentoses**) like ribose and deoxyribose are monosaccharides and can be absorbed, they are not a primary energy source in the diet and are not absorbed as efficiently or in as large quantities as the metabolically more significant 6-carbon monosaccharides (hexoses like glucose). - The question asks which *type* of carbohydrate is most efficiently absorbed, and **monosaccharides** as a general category (including 6-carbon sugars) are the most efficient.

Question 1

Pituicytes are seen in ?

Accepted Answer

Posterior lobe

Answer

Anterior lobe

Answer

Intermediate lobe

Answer

All of the options

Question 2

Which of the following is NOT a surface marking of the oblique fissure of the lung?

Accepted Answer

7th rib

Answer

6th costal cartilage

Answer

T3

Answer

5th rib

Question 3

What is the primary product of fatty acid oxidation (β-oxidation)?

Accepted Answer

Acetyl CoA

Answer

Malonyl CoA

Answer

Ketone bodies

Answer

Cholesterol

Question 4

What occurs during the stage of Grey hepatization?

Accepted Answer

Accumulation of fibrin

Answer

Red blood cells fill the alveoli

Answer

White blood cells fill the alveoli

Answer

Bacteria fill the alveoli

Question 5

Salty taste is due to?

Accepted Answer

Sodium ion channels

Answer

Calcium ion channels

Answer

G-protein coupled receptors

Answer

Proton channels

Question 6

Which substrate is both secreted and filtered by the kidneys?

Accepted Answer

Uric Acid

Answer

Glucose

Answer

Urea

Answer

Na+

Question 7

During acclimatization to hot environments, increased sweating efficiency is primarily due to enhanced sensitivity of which receptors?

Accepted Answer

Cholinergic receptors

Answer

Adrenergic receptors

Answer

Noradrenergic receptors

Answer

Dopaminergic receptors

Question 8

What is the primary factor that determines the resting membrane potential in a nerve fiber?

Accepted Answer

Is primarily determined by the equilibrium potential of potassium ions.

Answer

Is equal to the resting potential of cardiac muscle fibers.

Answer

Can be accurately measured using intracellular electrodes.

Answer

Increases with elevated extracellular potassium concentration.

Question 9

What is the average progressive velocity of human sperm under standard laboratory conditions?

Accepted Answer

1-3 mm/min

Answer

4-6 mm/min

Answer

6-9 mm/min

Answer

10-13 mm/min

Question 10

Which type of carbohydrate is absorbed most efficiently from the gastrointestinal tract?

Accepted Answer

Monosaccharides

Answer

Disaccharides

Answer

Polysaccharides

Answer

5-carbon sugars

NEET-PG 2012

Anatomy

Biochemistry

Pathology

Physiology