NEET-PG 2012 Practice Questions

Q: Where is the Bartholin gland situated?

Superficial perineal pouch. ***Superficial perineal pouch*** - The **Bartholin glands** are located posterolateral to the vaginal orifice within the boundaries of the **superficial perineal pouch** [1]. - They are covered by the **bulbospongiosus muscle** and their ducts open into the vestibule of the vagina [1]. *Deep perineal pouch* - This pouch contains structures like the **urethra**, part of the **vagina**, and the **deep transverse perineal muscle**, but not the Bartholin glands [2]. - It is located superior to the superficial perineal pouch and separated by the **perineal membrane**. *Inguinal canal* - The **inguinal canal** is a passage in the anterior abdominal wall that transmits the **round ligament of the uterus** in females and the **spermatic cord** in males. - It is anatomically distinct from the perineum and does not house the Bartholin glands. *Ischiorectal fossa* - The **ischiorectal fossae** are fat-filled spaces located lateral to the anal canal, inferior to the levator ani muscles. - They are known for their susceptibility to abscess formation but do not contain the Bartholin glands.

Q: Podocytes are seen in -

Bowman's capsule. **Bowman's capsule** - **Podocytes** are specialized epithelial cells that form the **visceral layer** of Bowman's capsule. They have foot processes (pedicels) that interdigitate to form slit diaphragms, which are crucial for the **filtration barrier** of the glomerulus [1]. - These cells facilitate the selective passage of water and small solutes from the blood into Bowman's space, while preventing the filtration of large proteins and blood cells. *Proximal convoluted tubule* - The **proximal convoluted tubule** is primarily involved in the **reabsorption** of essential nutrients, ions, and water from the filtrate back into the bloodstream [1]. - Its cells are characterized by a **brush border** (microvilli) and numerous mitochondria, indicating high metabolic activity, and are not podocytes [1]. *Distal convoluted tubule* - The **distal convoluted tubule** plays a role in fine-tuning the reabsorption of ions and water, under the influence of hormones like **aldosterone** and **ADH**. - Its cells lack the specialized foot processes and filtration function characteristic of podocytes. *Collecting tubule of the kidney* - The **collecting tubule** (or collecting duct) is involved in regulating water reabsorption and acid-base balance, responding to **ADH** to concentrate urine. - Its epithelial cells are principal cells and intercalated cells, which are different in structure and function from podocytes.

Q: The Watson-Crick model is for which type of DNA?

B DNA. ***B DNA*** - The **Watson-Crick model** describes the most common and stable form of DNA found in living organisms under physiological conditions. - **B-DNA** is a right-handed double helix, characterized by a **major and minor groove**, with approximately 10-10.5 base pairs per turn. *A DNA* - **A-DNA** is a **right-handed double helix** that forms under dehydrating conditions and is shorter and wider than B-DNA. - It has a more tilted base pair arrangement and is not the primary form described by the Watson-Crick model. *C DNA* - **C-DNA** is a less common **right-handed double helix** that forms under even lower hydration conditions and in the presence of certain ions. - It has fewer base pairs per turn than B-DNA, typically around 9.3 base pairs. *Z DNA* - **Z-DNA** is unique because it is a **left-handed double helix**, unlike the right-handed forms of A, B, and C DNA. - It is transiently formed in regions with a high concentration of **GC base pairs** and has a zigzag backbone, hence its name.

Q: Which of the following is a non-essential amino acid?

Tyrosine. ***Tyrosine*** - **Tyrosine** is considered a **non-essential amino acid** because the human body can synthesize it from the essential amino acid **phenylalanine**. - This synthesis occurs via the enzyme **phenylalanine hydroxylase**, making its dietary intake not strictly necessary if phenylalanine is available. *Phenylalanine* - **Phenylalanine** is an **essential amino acid**, meaning the human body **cannot synthesize it** and it must be obtained through the diet. - It serves as a precursor for various important molecules, including tyrosine, contributing to neurotransmitter synthesis. *Lysine* - **Lysine** is an **essential amino acid** that the human body **cannot synthesize** and must be acquired from dietary sources. - It plays a crucial role in **protein synthesis**, calcium absorption, and the production of hormones and enzymes. *Threonine* - **Threonine** is another example of an **essential amino acid** that the human body is **unable to produce** on its own. - It is important for the formation of **collagen** and elastin, and contributes to immune function.

Q: Which glycogen storage disease also presents as a lysosomal storage disease?

Pompe's disease. ***Pompe's disease*** - Also known as **glycogen storage disease type II**, it is caused by a deficiency of **acid alpha-glucosidase (GAA)**, a *lysosomal enzyme*. - This deficiency leads to the accumulation of **glycogen in lysosomes**, particularly affecting muscle tissue, thereby earning its classification as both a glycogen storage disease and a lysosomal storage disease. *Von Gierke's disease* - This is **glycogen storage disease type I** and is due to a deficiency in **glucose-6-phosphatase**. - It primarily affects the **liver and kidneys**, causing severe **hypoglycemia** and **lactic acidosis**, but it is not classified as a lysosomal storage disease. *McArdle's disease* - This is **glycogen storage disease type V**, caused by a deficiency in **muscle glycogen phosphorylase (myophosphorylase)**. - It manifests as **exercise intolerance** and muscle pain, but it does not involve lysosomal enzyme defects or glycogen accumulation in lysosomes. *Andersen's disease* - This is **glycogen storage disease type IV**, caused by a deficiency in the **glycogen branching enzyme**. - It leads to the formation of **abnormal glycogen structures**, primarily affecting the liver and causing early liver failure, but it is not a lysosomal storage disorder.

Q: Pyridoxine deficiency leads to altered metabolism of?

Tryptophan. ***Tryptophan*** - **Pyridoxine (vitamin B6)** is a critical coenzyme in the metabolism of **tryptophan**, particularly in its conversion to **niacin** and serotonin. - A deficiency leads to an accumulation of abnormal tryptophan metabolites, such as **xanthurenic acid**, which can be excreted in the urine. *Phenylalanine* - The metabolism of phenylalanine involves its conversion to tyrosine, a process catalyzed by **phenylalanine hydroxylase**, which does not directly require pyridoxine. - Deficiencies in phenylalanine metabolism often point to issues like **phenylketonuria**. *Methionine* - Methionine metabolism involves a cycle that generates **S-adenosylmethionine (SAM)** and then homocysteine. - While vitamin B6 is involved in the transsulfuration pathway (converting homocysteine to cysteine), its primary direct impact on methionine metabolism itself is less pronounced than on tryptophan. *Tyrosine* - Tyrosine is synthesized from phenylalanine and is a precursor for **catecholamines** and thyroid hormones. - Its metabolism does not directly rely on pyridoxine as a coenzyme in the main initial steps.

Q: The thickness of the endometrium at the time of implantation is:

7 - 10 mm. ***7 - 10 mm*** - At the time of **implantation** (day 6-10 post-fertilization, around day 20-24 of the menstrual cycle), the endometrium is in the **mid-secretory phase** and measures **7-10 mm** in thickness. - This is the **optimal thickness** for successful embryo implantation, characterized by a receptive endometrium with **decidualization**, **spiral artery development**, and **glycogen-rich glandular secretions**. - Endometrial thickness <7 mm is associated with **poor implantation rates** and reduced pregnancy success. *3 - 4 mm* - An endometrial thickness of 3-4 mm is **too thin** for successful implantation. - This thickness is typically seen in the **early proliferative phase** (immediately after menstruation), not during the implantation window. - Thin endometrium (<7 mm) is associated with **poor receptivity** and lower pregnancy rates in both natural conception and assisted reproduction. *20 - 30 mm* - An endometrial thickness of 20-30 mm is **abnormally thick** and not conducive to normal implantation. - Such thickness may indicate **endometrial hyperplasia**, **polyps**, or other pathological conditions requiring investigation. *30 - 40 mm* - An endometrial thickness of 30-40 mm is **severely abnormal** and would likely prevent successful implantation. - This extreme thickness suggests significant pathology such as **endometrial hyperplasia** or **malignancy** and requires urgent evaluation.

Q: E-cadherin gene deficiency is associated with which type of cancer?

Gastric cancer. **Correct: Gastric cancer** - **E-cadherin** is a crucial cell adhesion molecule, and its deficiency is strongly linked to **diffuse-type gastric cancer**. - Mutations in the **CDH1 gene**, which encodes E-cadherin, predispose individuals to **hereditary diffuse gastric cancer (HDGC)** due to loss of cell-cell adhesion. - This is a classic tumor suppressor gene, and germline mutations lead to an autosomal dominant cancer syndrome. *Incorrect: Intestinal cancer* - While E-cadherin plays a role in various epithelial cancers, its deficiency is not the primary driver or defining feature of intestinal cancer (colorectal cancer). - **Colorectal cancer** is more commonly associated with mutations in genes like **APC**, **KRAS**, **TP53**, and mismatch repair genes. *Incorrect: Thyroid cancer* - E-cadherin expression can be altered in thyroid cancers, but its deficiency is not the hallmark genetic event. - **Thyroid cancer** (especially papillary and follicular types) is more frequently linked to gene rearrangements (e.g., **RET/PTC**, **PAX8/PPARγ**) or point mutations (e.g., **BRAF**, **RAS**). *Incorrect: Pancreatic cancer* - Although E-cadherin can be down-regulated in pancreatic cancer, it is not the principal genetic deficiency. - **Pancreatic ductal adenocarcinoma** typically involves mutations in **KRAS**, **TP53**, **SMAD4**, and **CDKN2A**.

Q: Which histopathological feature is characteristic of chronic hepatitis?

Bridging necrosis. ***Bridging necrosis*** - Commonly seen in chronic hepatitis, bridging necrosis indicates severe liver injury and loss of hepatocyte integrity [1]. - Represents a critical finding in liver biopsy, reflecting ongoing inflammation and necrosis between portal areas and central veins [1]. *Councilman bodies* - These are apoptotic hepatocytes observed primarily in acute hepatitis, not chronic hepatitis. - They are indicative of **viral hepatitis** but are less specific for chronic conditions. *Balloning* - Refers to the ballooning degeneration of hepatocytes, commonly seen in fatty liver disease or acute hepatitis rather than chronic hepatitis. - Although it can occur in chronic conditions, it is not a definitive hallmark for chronic hepatitis specifically. *All* - This option is misleading as it suggests that all the listed features are definitive for chronic hepatitis, which is not accurate. - Individual features like **Councilman bodies** and **balloning** are more related to acute or different liver conditions, rather than chronic hepatitis [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Liver and Gallbladder, pp. 842-844.

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.

Question 1

Where is the Bartholin gland situated?

Accepted Answer

Superficial perineal pouch

Answer

Deep perineal pouch

Answer

Inguinal canal

Answer

Ischiorectal fossa

Question 2

Podocytes are seen in -

Accepted Answer

Bowman's capsule

Answer

Proximal convoluted tubule

Answer

Distal convoluted tubule

Answer

Collecting tubule of the kidney

Question 3

The Watson-Crick model is for which type of DNA?

Accepted Answer

B DNA

Answer

A DNA

Answer

C DNA

Answer

Z DNA

Question 4

Which of the following is a non-essential amino acid?

Accepted Answer

Tyrosine

Answer

Phenylalanine

Answer

Lysine

Answer

Threonine

Question 5

Which glycogen storage disease also presents as a lysosomal storage disease?

Accepted Answer

Pompe's disease

Answer

Von Gierke's disease

Answer

McArdle's disease

Answer

Andersen's disease

Question 6

Pyridoxine deficiency leads to altered metabolism of?

Accepted Answer

Tryptophan

Answer

Phenylalanine

Answer

Methionine

Answer

Tyrosine

Question 7

The thickness of the endometrium at the time of implantation is:

Accepted Answer

7 - 10 mm

Answer

20 - 30 mm

Answer

30 - 40 mm

Answer

3 - 4 mm

Question 8

E-cadherin gene deficiency is associated with which type of cancer?

Accepted Answer

Gastric cancer

Answer

Intestinal cancer

Answer

Pancreatic cancer

Answer

Thyroid cancer

Question 9

Which histopathological feature is characteristic of chronic hepatitis?

Accepted Answer

Bridging necrosis

Answer

Ballooning degeneration

Answer

Councilman bodies

Answer

None of the options

Question 10

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

NEET-PG 2012

Anatomy

Biochemistry

Obstetrics and Gynecology

Pathology

Physiology