NEET-PG 2012 Practice Questions

Q: What is the anatomical significance of the Rhinion in relation to the osseocartilaginous junction?

Rhinion. ***Correct Answer: Rhinion*** - The **rhinion** is the **most prominent anterior point of the nasal bone**, often palpable as a slight bump or angulation on the dorsum of the nose. - It marks the anatomical location of the **osseocartilaginous junction** of the nasal dorsum, where the bony nasal framework transitions to the cartilaginous framework. - This is the key anatomical landmark that defines the transition from bone to cartilage in the external nose. *Incorrect: Nasion* - The **nasion** is located at the **root of the nose**, specifically at the most anterior and superior point of the nasofrontal suture. - It is a bony landmark and does not directly relate to the osseocartilaginous junction of the nasal dorsum. *Incorrect: Radix* - The **radix** (or nasal root) refers to the **uppermost part of the nose**, corresponding to the nasion. - It defines the point where the nose begins to project from the forehead and is a bony landmark, not directly related to the osseocartilaginous junction. *Incorrect: Columella* - The **columella** is the **fleshy, narrow strip of tissue that separates the nostrils**. - It forms the inferior segment of the nasal septum and is composed of skin, soft tissue, and the medial crura of the alar cartilages, thus having no direct relation to the osseocartilaginous junction of the nasal dorsum.

Q: What is the lower limit of the retropharyngeal space?

Bifurcation of trachea. Bifurcation of trachea - The retropharyngeal space extends inferiorly to approximately the level of T4-T5 vertebrae, corresponding to the bifurcation of the trachea and the superior mediastinum. - This space lies between the buccopharyngeal fascia (posterior to pharynx) and the alar layer of prevertebral fascia. - Clinically, infections or abscesses in this space can descend into the posterior mediastinum, making knowledge of this inferior extent crucial for surgical management. - Note: Some anatomical texts describe the space ending at T1-T2, but for clinical and surgical purposes, the functional inferior limit extends to the bifurcation of the trachea. C7 - While some texts describe the retropharyngeal space as terminating around C7 (level of the lower border of cricoid cartilage), this represents the narrower definition. - The clinical and surgical definition extends the space further inferiorly to allow for tracking of infections into the chest. - C7 alone does not represent the accepted lower limit for examination purposes. 4th esophageal constriction - The fourth esophageal constriction is not a standard anatomical landmark (esophagus has 3-4 constrictions depending on classification). - Esophageal constrictions are luminal narrowings within the esophagus itself and do not define the boundaries of the retropharyngeal space, which is a fascial space posterior to both pharynx and esophagus. None of the options - This is incorrect because bifurcation of the trachea is the recognized lower limit of the retropharyngeal space for clinical and examination purposes. - Understanding this anatomical boundary is essential for predicting the spread of deep neck space infections.

Q: Primordial germ cells are derived from:

Yolk sac. ***Yolk sac*** - **Primordial germ cells (PGCs)** arise from **epiblast** cells but are first identifiable in the wall of the **yolk sac** during the **3rd week** of development. - From the yolk sac, they migrate during the **4th-6th week** through the dorsal mesentery to reach the developing **genital ridges** (gonads) where they form **gametes** [2]. - The yolk sac is considered the site where PGCs are recognized and begin their journey to the gonads. *Neural crest* - Neural crest cells are multipotent cells that migrate to various locations and differentiate into structures like **neurons**, **glial cells**, **melanocytes**, and **facial cartilage**, not germ cells. - They arise from the dorsal part of the **neural tube** during neurulation. *Genital ridge* - The genital ridge is the embryonic structure that develops into the **gonads** (testes or ovaries) [1]. - Primordial germ cells migrate *to* the genital ridge, but they do not originate *from* it — it is their destination, not their source. *Somatopleuritic mesoderm* - **Somatopleuritic mesoderm** (somatic mesoderm) forms the **parietal layer** of serous membranes, the dermis of the body wall, and the skeletal elements of the limbs. - It does not give rise to **primordial germ cells**.

Q: Protein refolding is carried out by?

Chaperone. ***Chaperone*** - **Chaperone proteins** assist in the proper folding of other proteins, particularly during stress conditions like heat shock, by preventing **aggregation** and promoting correct conformation. - They do not become part of the final functional protein but transiently bind during the folding process, thus facilitating **protein refolding** and assembly. *Valine* - **Valine** is an **essential amino acid** and a building block for proteins, but it does not play a direct role in protein refolding. - It contributes to the **hydrophobic core** of proteins due to its non-polar side chain, influencing protein structure but not managing the folding process. *Threonine* - **Threonine** is an **essential amino acid** with a polar side chain, often involved in **glycosylation** and phosphorylation, but not in the complex process of protein refolding. - Its hydroxyl group can participate in **hydrogen bonding**, influencing protein stability and interactions, but not acting as a folding catalyst. *Aspartate* - **Aspartate** is a **non-essential acidic amino acid** that can be involved in various metabolic pathways and is a component of proteins. - Its acidic side chain can form **salt bridges** and hydrogen bonds, contributing to the protein's overall charge and structure, but it does not actively oversee protein refolding.

Q: Which condition is commonly associated with Disseminated Intravascular Coagulation (D.I.C.)?

Acute promyelocytic leukemia. ***Acute promyelocytic leukemia*** - **Disseminated Intravascular Coagulation (D.I.C.)** is commonly associated with acute promyelocytic leukemia due to the release of **tissue factor** from promyelocytes [1]. - Patients typically present with **severe bleeding** and coagulopathy [1], driven by the rapid proliferation of these abnormal cells. *Acute myelomonocytic leukemia* - While this type of leukemia presents with myelomonocytic features, it is less frequently associated with **D.I.C.** compared to acute promyelocytic leukemia. - This condition is often characterized by **monocytic infiltration** but does not typically cause the severe coagulopathy associated with D.I.C. *Autoimmune hemolytic anemia* - This condition causes **hemolysis** due to antibodies but is mainly associated with **anemia**, not a coagulation disorder like D.I.C. - **D.I.C.** involves widespread **consumption coagulopathy** [1], which is not a feature of autoimmune hemolytic anemia. *CMC* - CMC refers to **Chronic Myeloid Leukemia**, which does not commonly lead to **D.I.C.** and presents primarily with splenomegaly and **chronic symptoms**. - The coagulation profile in CMC tends to be stable, with no link to the acute coagulopathy seen in D.I.C.

Q: Which of the following hormones does not mediate its action through cAMP?

Estrogen. ***Estrogen*** - **Estrogen** is a **steroid hormone** that mediates its action by binding to intracellular receptors, forming a complex that directly influences gene transcription. - Steroid hormones, due to their **lipophilicity**, can cross the cell membrane and do not typically rely on cell surface receptors or second messengers like cAMP. *Glucagon* - **Glucagon** acts on a **G protein-coupled receptor (GPCR)**, specifically a Gs-coupled receptor, leading to the activation of adenylyl cyclase. - This activation increases the intracellular concentration of **cAMP**, which then activates protein kinase A to mediate its effects, primarily on glucose metabolism. *Follicle stimulating hormone* - **FSH** binds to a **GPCR** on target cells, activating the Gs protein pathway. - This activation stimulates **adenylyl cyclase** and increases intracellular **cAMP** levels, which are critical for its role in gamete development. *Luteinizing hormone* - **LH**, like FSH, binds to a cell surface **GPCR** that activates the Gs protein. - This leads to the stimulation of **adenylyl cyclase** and an increase in **cAMP**, mediating its effects on steroidogenesis and ovulation.

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.

Q: In which condition is venous blood most commonly observed to have a high hematocrit in routine clinical practice?

Dehydration. Dehydration - In **dehydration**, the total body water is reduced, leading to a decrease in plasma volume [1, 5]. This concentrates the red blood cells, resulting in a relatively **high hematocrit**. [3] - This is a common finding as the body attempts to conserve fluid, making it a primary cause of **elevated hematocrit** in clinical practice. *Anemia* - **Anemia** is characterized by a decrease in the number of red blood cells or a reduced hemoglobin concentration, which would lead to a **low hematocrit**, not a high one [2]. - This condition involves insufficient oxygen-carrying capacity due to a deficiency in red blood cells or hemoglobin [2]. *Hypervolemia* - **Hypervolemia** describes an excess of fluid in the blood, which would dilute the blood components, leading to a relatively **low hematocrit** [1]. - This condition is often associated with conditions like heart failure or kidney disease, where fluid retention is common. *Acute blood loss* - In **acute blood loss**, the loss of whole blood immediately after the event would initially reduce both red blood cells and plasma proportionally, not immediately raising hematocrit [2]. - As the body attempts to compensate by shifting extravascular fluid into the circulation, this would further dilute the blood, eventually leading to a **decreased hematocrit** [2].

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.

Question 1

What is the anatomical significance of the Rhinion in relation to the osseocartilaginous junction?

Accepted Answer

Rhinion

Answer

Nasion

Answer

Radix

Answer

Columella

Question 2

What is the lower limit of the retropharyngeal space?

Accepted Answer

Bifurcation of trachea

Answer

4th esophageal constriction

Answer

C7

Answer

None of the options

Question 3

Primordial germ cells are derived from:

Accepted Answer

Yolk sac

Answer

Neural crest

Answer

Genital ridge

Answer

Somatopleuritic mesoderm

Question 4

Protein refolding is carried out by?

Accepted Answer

Chaperone

Answer

Valine

Answer

Threonine

Answer

Aspartate

Question 5

Which condition is commonly associated with Disseminated Intravascular Coagulation (D.I.C.)?

Accepted Answer

Acute promyelocytic leukemia

Answer

Acute myelomonocytic leukemia

Answer

Chronic myeloid leukemia

Answer

Autoimmune hemolytic anemia

Question 6

Which of the following hormones does not mediate its action through cAMP?

Accepted Answer

Estrogen

Answer

Glucagon

Answer

Follicle stimulating hormone

Answer

Luteinizing hormone

Question 7

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

Accepted Answer

Monosaccharides

Answer

Disaccharides

Answer

Polysaccharides

Answer

5-carbon sugars

Question 8

A man slept with his head over his forearm. The next morning, he complains of tingling and numbness over the forearm. If this were primarily due to hypoxia affecting nerve fibers, which of the following statements about nerve fiber sensitivity to hypoxia is correct?

Accepted Answer

B fibers are most sensitive to hypoxia, followed by A fibers, and C fibers are least sensitive.

Answer

All nerve fibers are equally sensitive to hypoxia.

Answer

C fibers are most sensitive to hypoxia, followed by B fibers, and A fibers are least sensitive.

Answer

A fibers are most sensitive to hypoxia, followed by B fibers, and C fibers are least sensitive.

Question 9

In which condition is venous blood most commonly observed to have a high hematocrit in routine clinical practice?

Accepted Answer

Dehydration

Answer

Anemia

Answer

Hypervolemia

Answer

Acute blood loss

Question 10

Salty taste is due to?

Accepted Answer

Sodium ion channels

Answer

Calcium ion channels

Answer

G-protein coupled receptors

Answer

Proton channels

NEET-PG 2012

Anatomy

Biochemistry

Pathology

Physiology