NEET-PG 2015 Practice Questions

Q: Which of the following is not a derivative of foregut?

Cecum. ***Cecum*** - The **cecum** and the entire large intestine (except the distal third of the transverse colon) are derivatives of the **midgut** [1]. - The midgut is supplied by the **superior mesenteric artery**, differentiating it developmentally from the foregut. *First part of the duodenum* - The **first part of the duodenum** (from the pylorus to the major duodenal papilla) is derived from the **foregut**. - This section receives its blood supply from branches of the **celiac trunk**, consistent with its foregut origin. *Liver* - The **liver** develops as a budding from the distal foregut and is therefore a **foregut derivative** [2]. - It plays a crucial role in metabolism and detoxification, consistent with its early development from this segment. *Pancreas* - The **pancreas** develops from dorsal and ventral buds of the distal foregut, making it a **foregut derivative**. - Both its exocrine and endocrine functions are vital for digestion and glucose homeostasis.

Q: Which of the following statements about the enzymes involved in the conversion of glucose to glucose-6-phosphate in glycolysis is true?

Glucokinase is induced by insulin.. ***Glucokinase is induced by insulin.*** - **Insulin** promotes glucose uptake and utilization in the liver and pancreatic beta cells, where glucokinase is primarily expressed. - Induction of **glucokinase** by insulin ensures that glucose is efficiently phosphorylated and trapped within hepatocytes when blood glucose levels are high. - This is a key mechanism for postprandial glucose homeostasis. *Incorrect: Hexokinase is specific for glucose.* - **Hexokinase** is NOT specific for glucose; it can phosphorylate various hexoses including **fructose**, **mannose**, and **galactose**. - Its broad substrate specificity distinguishes it from glucokinase, which has greater specificity for glucose. *Incorrect: Glucokinase is inhibited by glucose-6-phosphate.* - Unlike **hexokinase**, which is subject to product inhibition by glucose-6-phosphate, **glucokinase is NOT inhibited** by its product. - This lack of feedback inhibition allows glucokinase to continue phosphorylating glucose even when glucose-6-phosphate levels are elevated, which is appropriate for its role as a glucose sensor in liver and pancreatic beta cells. *Incorrect: Hexokinase has a high Km for glucose.* - **Hexokinase** has a **low Km** (~0.1 mM) for glucose, meaning it has high affinity and is saturated at normal blood glucose levels. - In contrast, **glucokinase** has a high Km (~10 mM), allowing it to respond proportionally to changes in blood glucose concentration.

Q: Abnormal proteins which are bound to ubiquitin are degraded in -

Proteasomes. ***Proteasomes*** - **Proteasomes** are multi-subunit protein complexes responsible for degrading **ubiquitin-tagged proteins**. - This degradation is a tightly regulated process essential for cell cycle control, gene expression, and immune response. *Golgi apparatus* - The **Golgi apparatus** primarily functions in modifying, sorting, and packaging proteins and lipids synthesized in the Endoplasmic Reticulum. - It does not directly participate in the degradation of **ubiquitin-bound proteins**. *Smooth ER* - The **smooth endoplasmic reticulum (SER)** is involved in lipid synthesis, detoxification of drugs and poisons, and storage of calcium ions. - It lacks ribosomes and is not directly implicated in the degradation of misfolded proteins tagged with ubiquitin. *Lysosomes* - **Lysosomes** are organelles containing various hydrolytic enzymes that break down waste materials and cellular debris, as well as foreign invaders like bacteria. - While they degrade proteins, they primarily target **extracellular proteins** taken up by endocytosis or cellular components via **autophagy**, not specifically ubiquitin-bound proteins.

Q: What is the most common nephropathy associated with malignancy?

Membranous glomerulonephritis. ***Membranous glomerulonephritis*** - **Membranous glomerulonephritis** has the strongest and most frequent association with solid organ malignancies, particularly in older patients. - While other glomerulopathies can be linked to cancer, **membranous nephropathy** is the most common paraneoplastic glomerulopathy in adults. *Focal segmental glomerulosclerosis (FSGS)* - While FSGS can be associated with certain cancers, particularly hematological malignancies and HIV-associated nephropathy, it is **less common** than membranous nephropathy in solid tumors. - The link is often with **HIV-associated nephropathy** or direct tumor effects rather than a paraneoplastic syndrome. *Minimal change disease* - Minimal change disease is predominantly seen in **children** and is less frequently associated with malignancy compared to membranous nephropathy. - When associated with malignancy, it is typically with **lymphoproliferative disorders** like Hodgkin lymphoma. *IgA nephropathy* - **IgA nephropathy** is the most common primary glomerulonephritis worldwide but has a **weak and inconsistent association** with malignancy. - Its presence alongside cancer is often coincidental rather than directly causative.

Q: Obliterative endarteritis in vasa vasorum is seen in -

Tertiary Syphilis. ***Tertiary Syphilis*** - **Obliterative endarteritis** of the **vasa vasorum** is a hallmark pathological finding in tertiary syphilis, particularly affecting the **aorta**. - This inflammation and occlusion of the small blood vessels supplying the aorta lead to **ischemic injury** of the aortic wall, causing **aneurysms** and **aortic regurgitation**. *Essential Hypertension* - While hypertension can lead to vascular changes like **arteriolosclerosis** and **hyperplastic arteriolosclerosis**, it does not typically involve obliterative endarteritis of the vasa vasorum. - The vascular damage in essential hypertension is more generalized to smaller arteries and arterioles, not specifically the vasa vasorum. *Systemic Lupus Erythematosus* - SLE is an **autoimmune disease** that can cause **vasculitis**, but the specific pattern of obliterative endarteritis of the vasa vasorum is not characteristic. - Vascular involvement in SLE is diverse, ranging from small vessel vasculitis to accelerated atherosclerosis, but distinct from syphilitic changes. *Pulmonary Tuberculosis* - Tuberculosis is primarily an **infectious granulomatous disease** affecting the lungs and other organs; it does not typically cause obliterative endarteritis of the vasa vasorum. - Although it can cause vascular complications like **aneurysms** (e.g., Rasmussen's aneurysm) due to erosion, the underlying mechanism is not the same as syphilitic changes.

Q: Which of the following is an action of muscarinic cholinergic receptors?

Decreased heart rate. ***Decreased heart rate*** - Activation of **muscarinic cholinergic receptors (M2 receptors)** in the heart leads to a decrease in heart rate and conduction velocity. - This effect is mediated by the **vagus nerve (parasympathetic nervous system)**, which releases acetylcholine to act on these receptors. - This is the **most characteristic and clinically significant cardiovascular effect** of muscarinic receptor activation, making it the expected answer. *Skeletal muscle contraction* - **Skeletal muscle contraction** is mediated by **nicotinic acetylcholine receptors (nAChRs)** at the **neuromuscular junction**, NOT muscarinic receptors. - Nicotinic receptors are **ligand-gated ion channels** that cause direct depolarization and muscle contraction when activated. - This is the only option that is **NOT a muscarinic receptor action**. *Acid secretion in stomach* - **Gastric acid secretion** IS mediated by **M3 muscarinic receptors** on parietal cells. - Acetylcholine from the vagus nerve directly stimulates parietal cells and also stimulates histamine release from enterochromaffin-like cells. - While this is a valid muscarinic action, in the context of distinguishing muscarinic effects, **cardiac effects** (decreased heart rate) are more emphasized as the classic teaching point. *Salivation and lacrimation* - **Salivation and lacrimation** ARE mediated by **M3 muscarinic receptors** in exocrine glands. - These are classic parasympathetic/muscarinic effects taught in physiology. - However, when distinguishing key muscarinic actions, **M2 receptor-mediated cardiac effects** are typically highlighted as the primary cardiovascular manifestation, while M3 effects on glands are secondary teaching points.

Q: Volume of distribution of a drug is 500 ml and target concentration of drug in blood is 5 g/L. 20% of administered drug is reached to systemic circulation. What will be the loading dose of that drug -

12.5 gm. ***12.5 gm*** - The formula for loading dose (LD) is: LD = (Target Concentration × Volume of Distribution) / Bioavailability. - Given: Target Concentration = 5 g/L, Volume of Distribution = 500 mL = 0.5 L, Bioavailability = 20% = 0.2. - So, LD = (5 g/L × 0.5 L) / 0.2 = 2.5 g / 0.2 = **12.5 g**. *1 gm* - This value would be obtained if the target concentration was 2 g/L with 100% bioavailability, or if the calculation incorrectly handled the volume or bioavailability factor. - It does not account for the specified **bioavailability of 20%** or the given target concentration and volume of distribution. *5 gm* - This result would be obtained if the bioavailability was assumed to be 50% (LD = 2.5 g / 0.5 = 5 g), or if the volume of distribution was incorrectly used in the calculation. - This option does not correctly factor in the **20% bioavailability** of the administered drug. *25 gm* - This value would result from mistakes such as dividing by bioavailability of 10% instead of 20% (LD = 2.5 g / 0.1 = 25 g), or by multiplying bioavailability instead of dividing by it. - This answer significantly **overestimates** the required dose, which could lead to drug toxicity.

Q: Which of the following is not a common side effect of clonidine?

Diarrhea. ***Diarrhea*** - **Clonidine** commonly causes **constipation**, not diarrhea, due to its **alpha-2 adrenergic agonist** effects, which decrease gastrointestinal motility. - Diarrhea is not typically associated with clonidine's mechanism of action or adverse effect profile. *Xerostomia* - **Xerostomia** (dry mouth) is a very common side effect of **clonidine** occurring in up to 40% of patients. - This results from **alpha-2 agonist** activity that reduces sympathetic stimulation of salivary gland secretions. - This symptom can significantly impact patient compliance and quality of life. *Sedation* - **Sedation** is a frequent side effect of **clonidine**, particularly when initiating treatment or increasing dosage, because it acts as an **alpha-2 agonist** in the central nervous system, reducing sympathetic outflow and promoting drowsiness. - Patients are often advised to avoid driving or operating heavy machinery until they know how the medication affects them. *Impotency* - **Impotency** or **erectile dysfunction** is a recognized and common sexual side effect of **clonidine**, which can interfere with quality of life and adherence to treatment for hypertension. - This effect is related to the drug's impact on the autonomic nervous system and vascular tone through central alpha-2 agonism.

Q: Which of the following oral antidiabetic drugs is an insulin secretagogue?

Nateglinide. **Nateglinide** - **Nateglinide** is a **meglitinide**, which is a type of **insulin secretagogue**. - It stimulates **insulin release** from pancreatic beta cells by blocking ATP-sensitive potassium channels. *Metformin* - **Metformin** is a **biguanide** that primarily works by **decreasing hepatic glucose production** and increasing insulin sensitivity in peripheral tissues. - It does not directly stimulate insulin secretion. *Pioglitazone* - **Pioglitazone** is a **thiazolidinedione** (TZD) that improves insulin sensitivity by activating **PPAR-gamma receptors**. - It does not directly affect insulin secretion but rather enhances the body's response to existing insulin. *Acarbose* - **Acarbose** is an **alpha-glucosidase inhibitor** that delays the digestion and absorption of carbohydrates in the small intestine. - This reduces postprandial glucose excursions and does not directly stimulate insulin secretion.

Q: What physiological mechanism is responsible for the increase in the duration of expiration?

Hering-Breuer reflex. ***Hering-Breuer reflex*** - The **Hering-Breuer reflex** is initiated by **stretch receptors in the bronchi and bronchioles** which are activated during lung inflation. - This reflex **inhibits inspiration** and **prolongs expiration**, preventing overinflation of the lungs. *J-reflex* - The **J-reflex** is stimulated by **juxtacapillary (J) receptors** in the alveolar walls, usually in response to pulmonary edema or congestion. - It typically causes **rapid, shallow breathing** and **bronchoconstriction**, not prolonged expiration. *Head's paradoxical reflex* - **Head's paradoxical reflex** (also known as the **inflation reflex** in newborns) involves an inspiratory effort triggered by lung inflation, often overcoming the Hering-Breuer reflex in specific conditions. - It tends to **increase respiratory rate** and depth, not prolong expiration. *Proprioceptors* - **Proprioceptors** are sensory receptors in muscles, tendons, and joints that provide information about body position and movement. - While they can influence respiration during exercise, they are not primarily responsible for directly **increasing the duration of expiration** as a reflex mechanism against overinflation.

Question 1

Which of the following is not a derivative of foregut?

Accepted Answer

Cecum

Answer

Liver

Answer

Pancreas

Answer

First part of the duodenum

Question 2

Which of the following statements about the enzymes involved in the conversion of glucose to glucose-6-phosphate in glycolysis is true?

Accepted Answer

Glucokinase is induced by insulin.

Answer

Hexokinase is specific for glucose.

Answer

Glucokinase is inhibited by glucose-6-phosphate.

Answer

Hexokinase has a high Km for glucose.

Question 3

Abnormal proteins which are bound to ubiquitin are degraded in -

Accepted Answer

Proteasomes

Answer

Golgi apparatus

Answer

Smooth ER

Answer

Lysosomes

Question 4

What is the most common nephropathy associated with malignancy?

Accepted Answer

Membranous glomerulonephritis

Answer

Focal segmental glomerulosclerosis (FSGS)

Answer

Minimal change disease

Answer

IgA nephropathy

Question 5

Obliterative endarteritis in vasa vasorum is seen in -

Accepted Answer

Tertiary Syphilis

Answer

Essential Hypertension

Answer

Systemic Lupus Erythematosus

Answer

Pulmonary Tuberculosis

Question 6

Which of the following is an action of muscarinic cholinergic receptors?

Accepted Answer

Decreased heart rate

Answer

Skeletal muscle contraction

Answer

Acid secretion in stomach

Answer

Salivation and lacrimation

Question 7

Volume of distribution of a drug is 500 ml and target concentration of drug in blood is 5 g/L. 20% of administered drug is reached to systemic circulation. What will be the loading dose of that drug -

Accepted Answer

12.5 gm

Answer

1 gm

Answer

5 gm

Answer

25 gm

Question 8

Which of the following is not a common side effect of clonidine?

Accepted Answer

Diarrhea

Answer

Xerostomia

Answer

Sedation

Answer

Impotency

Question 9

Which of the following oral antidiabetic drugs is an insulin secretagogue?

Accepted Answer

Nateglinide

Answer

Metformin

Answer

Pioglitazone

Answer

Acarbose

Question 10

What physiological mechanism is responsible for the increase in the duration of expiration?

Accepted Answer

Hering-Breuer reflex

Answer

J-reflex

Answer

Head's paradoxical reflex

Answer

Proprioceptors

NEET-PG 2015

Anatomy

Biochemistry

Pathology

Pharmacology

Physiology