NEET-PG 2013 Practice Questions

Q: Which of the following plant components is not fermented by gastrointestinal microorganisms?

Lignin. ***Lignin*** - **Lignin** is a complex polymer found in plant cell walls that is highly resistant to degradation by digestive enzymes and microbial fermentation in the gastrointestinal tract. - Its complex, cross-linked structure makes it **non-fermentable** by the microorganisms typically present in the human gut. *Cellulose* - **Cellulose** is a major component of plant cell walls and is a type of dietary fiber that can be fermented by certain gut bacteria. - While humans lack the enzymes to digest cellulose, colonic microorganisms possess cellulases that break it down into **short-chain fatty acids (SCFAs)**. *Hemicellulose* - **Hemicellulose** is a diverse group of plant polysaccharides that are a significant source of fermentable fiber for gut microbiota. - It is readily broken down by gastrointestinal bacteria into **SCFAs** and gases, contributing to colonic health. *Pectin* - **Pectin** is a soluble dietary fiber found in fruits and vegetables, known for its gel-forming properties. - It is highly fermentable by gut microorganisms, leading to the production of **SCFAs** like butyrate, propionate, and acetate.

Q: What is the primary reason for the detergent action of bile salts?

Amphipathic nature. ***Amphipathic nature*** - Bile salts are **amphipathic molecules**, meaning they have both **hydrophilic (water-loving)** and **hydrophobic (water-fearing)** regions. - This dual nature allows them to emulsify fats by surrounding lipid droplets with their hydrophobic ends dissolving in the fat and their hydrophilic ends facing the aqueous environment, stabilizing the emulsion. *Hydrophobic properties* - While bile salts do possess **hydrophobic regions**, these alone are not sufficient for detergent action. - The ability to interact with both oil and water phases simultaneously is crucial for their role in **emulsification**. *Acts as a zwitterion* - A zwitterion is a molecule with both a **positive and negative charge**, but an overall neutral charge. - This property is not the primary mechanism behind the **detergent action** of bile salts, which relies more on their ability to solubilize fats. *None of the options* - The **amphipathic nature** is indeed the primary reason for the detergent action; therefore, this option is incorrect.

Q: Glucagon stimulates

Gluconeogenesis. ***Gluconeogenesis*** - **Glucagon** is a hormone that primarily acts to raise **blood glucose levels** by stimulating the production of glucose from non-carbohydrate sources. - This process, **gluconeogenesis**, occurs mainly in the liver and is initiated by glucagon to counteract hypoglycemia. *Glycogenesis* - **Glycogenesis** is the process of synthesizing **glycogen** from glucose and is primarily stimulated by insulin when blood glucose levels are high. - Glucagon's role is to *inhibit* glycogen synthesis and instead promote glycogen breakdown. *Fatty acid synthesis* - **Fatty acid synthesis** is an anabolic process that primarily occurs when there is an excess of energy and glucose, often stimulated by **insulin**. - Glucagon generally has an **inhibitory effect** on fatty acid synthesis, as its main goal is to mobilize energy stores, not create them. *Glycolysis* - **Glycolysis** is the breakdown of glucose to produce energy, and it is stimulated when glucose is abundant and energy is needed. - Glucagon primarily acts to *inhibit* glycolysis in the liver, thereby conserving glucose for use by other tissues and promoting its release into the bloodstream.

Q: Anemia with reticulocytosis is seen in -

Hemolysis. ***Hemolysis*** - Reticulocytosis indicates a compensatory response to anemia, often occurring in hemolytic processes where the **bone marrow increases red blood cell production** in response to red blood cell destruction. - Conditions like **sickle cell disease** or **autoimmune hemolytic anemia** lead to hemolysis, further confirming increased reticulocyte count. *Iron deficiency anemia* - Typically presents with a **low reticulocyte count** as the bone marrow does not have sufficient iron to produce new red blood cells. - This condition is characterized by **microcytic, hypochromic** red blood cells due to inadequate iron stores. *Vitamin B12 deficiency* - Often results in a **macrocytic anemia** with a variable reticulocyte count; however, reticulocytosis is generally not seen initially. - This deficiency affects DNA synthesis, leading to ineffective erythropoiesis and the presence of **megaloblastic changes**. *Aplastic anemia* - Characterized by a **decrease in all types of blood cells** (pancytopenia) and typically has a **low reticulocyte count** due to bone marrow failure. - There is insufficient production of red blood cells, hence **reticulocytosis is not observed**.

Q: Which of the following is a second-generation beta blocker?

Atenolol. ***Atenolol*** - **Atenolol** is a **second-generation beta blocker** characterized by its **cardioselectivity**, meaning it primarily blocks beta-1 receptors in the heart. - This selectively reduces heart rate and contractility with fewer respiratory side effects compared to non-selective agents. *Propranolol* - **Propranolol** is a **first-generation non-selective beta blocker**, meaning it blocks both beta-1 and beta-2 adrenergic receptors. - Its non-selective action can cause significant bronchoconstriction, making it less suitable for patients with respiratory conditions. *Timolol* - **Timolol** is also a **first-generation non-selective beta blocker** commonly used in ophthalmic preparations for glaucoma. - It blocks both beta-1 and beta-2 receptors and does not possess the cardioselectivity of second-generation agents. *Nadolol* - **Nadolol** is another **first-generation non-selective beta blocker** with a long duration of action due to its extensive plasma half-life. - Like other first-generation agents, it lacks cardioselectivity and blocks both beta-1 and beta-2 receptors.

Q: Which of the following is the most accurate measure of Glomerular Filtration Rate (GFR)?

Iothalamate Clearance. ***Iothalamate Clearance*** - **Iothalamate clearance** is considered the **gold standard** for directly measuring GFR in clinical practice because it is a substance that is freely filtered by the glomerulus and is neither reabsorbed nor secreted by the renal tubules. - This method provides the most accurate and precise assessment of kidney function by quantifying the actual GFR, often used in research settings or for precise diagnosis. - **Note:** Inulin clearance is the traditional reference standard, but iothalamate is more practical and widely used clinically as it can be measured using radioactive or non-radioactive methods. *Serum creatinine* - **Serum creatinine** is a commonly used biomarker but is an **imperfect measure** of GFR because it can be influenced by factors like muscle mass, diet, and certain medications. - Its levels can remain within the normal range even when GFR has significantly decreased, especially in the early stages of kidney disease. *Cystatin C* - **Cystatin C** is a protein produced by most nucleated cells and is also freely filtered by the glomerulus, with less influence from muscle mass and diet compared to creatinine. - While considered a better marker than serum creatinine, it is still an **estimated measure** and is more expensive and less widely available than creatinine, and can be affected by inflammation or thyroid dysfunction. *Creatinine Clearance* - **Creatinine clearance** (often estimated using urine and serum creatinine levels over a timed collection) attempts to approximate GFR but can be **inaccurate** due to incomplete urine collection and tubular secretion of creatinine. - The **creatinine secretion** by the renal tubules leads to an overestimation of the true GFR, making it less accurate than direct measurement methods.

Q: Normal renal threshold for glucose is at plasma glucose level ?

200 mg/dl. ** _200 mg/dl_ ** - The **renal threshold for glucose** represents the plasma glucose concentration at which the kidneys begin to excrete glucose into the urine. - This typically occurs when the glucose level exceeds the reabsorptive capacity of the renal tubules, usually around **180-200 mg/dL**. * _100 mg/dl_ * - A plasma glucose level of **100 mg/dL** is within the normal fasting range and well below the renal threshold. - At this level, virtually all filtered glucose is reabsorbed by the renal tubules, and no glucose appears in the urine. * _300 mg/dl_ * - A plasma glucose level of **300 mg/dL** is significantly above the renal threshold for glucose. - At this concentration, the kidney's reabsorptive capacity is overwhelmed, leading to substantial **glucosuria** (glucose in the urine). * _400 mg/dl_ * - A plasma glucose level of **400 mg/dL** is severely elevated and far exceeds the renal threshold. - This level would result in significant glucose excretion in the urine and is indicative of uncontrolled hyperglycemia, as seen in **diabetes mellitus**.

Q: Which hormone is secreted by the "Delta cells" of the stomach?

Somatostatin. ***Somatostatin*** - **Delta cells (D cells)** in the stomach and pancreas secrete **somatostatin**, a potent inhibitory hormone. - Somatostatin **inhibits the release of gastrin**, histamine, secretin, cholecystokinin, and gastric acid secretion, acting as a "universal off switch." *Cholecystokinin* - **Cholecystokinin (CCK)** is primarily secreted by **I cells** in the duodenum and jejunum. - Its main functions include stimulating gallbladder contraction and pancreatic enzyme secretion. *Gastrin-releasing peptide* - **Gastrin-releasing peptide (GRP)**, also known as **bombesin**, is a neuropeptide released from **enteric neurons**. - It stimulates the release of **gastrin** from G cells. *Secretin* - **Secretin** is secreted by **S cells** in the duodenum in response to acidic chyme entering the small intestine. - Its primary role is to stimulate the pancreas to release **bicarbonate-rich fluid** to neutralize gastric acid.

Q: Sugars are primarily absorbed in?

Jejunum. ***Jejunum*** - The **jejunum** is the primary site for the absorption of most digested nutrients, including the vast majority of **monosaccharides** (simple sugars like glucose, fructose, and galactose). - Its structure, with numerous **plicae circulares**, villi, and microvilli, provides a large surface area optimized for efficient nutrient uptake. *Duodenum* - The **duodenum** is mainly involved in the **chemical digestion** of food, receiving chyme from the stomach and mixing it with digestive enzymes from the pancreas and bile from the liver. - While some minimal absorption can occur, it is not the primary site for extensive sugar absorption. *Ileum* - The **ileum** is mainly responsible for the absorption of **vitamin B12** and **bile salts**. - Although some residual nutrient absorption can happen here if the jejunum is compromised, it is not the primary physiological site for sugar absorption. *Ascending colon* - The **ascending colon** is primarily involved in the absorption of **water and electrolytes**, forming solid stool. - It does not significantly absorb sugars; undigested carbohydrates reaching the colon are typically fermented by gut bacteria.

Q: Which of the following is the primary site of gastrin production?

Gastric G cells. ***Gastric G cells*** - **G cells**, primarily located in the **antrum of the stomach**, are the main site for **gastrin production** - Gastrin is a hormone that stimulates the secretion of **gastric acid** by the parietal cells in the oxyntic glands of the stomach - G cells are specialized endocrine cells that release gastrin in response to gastric distension, amino acids, and vagal stimulation *Pancreas* - The pancreas produces hormones such as **insulin** and **glucagon**, and digestive enzymes like **amylase** and **lipase** - While the pancreas does contain some hormone-producing cells, it is not the primary site for gastrin synthesis *Pituitary gland* - The **pituitary gland** is the master endocrine gland, regulating various **hormonal axes** like thyroid, adrenal, and reproductive functions - It does not produce gastrin; its hormones include **growth hormone**, **prolactin**, **TSH**, **ACTH**, **FSH**, and **LH** *Gastric chief cells* - Chief cells (also called zymogenic cells) are located in the **gastric glands of the fundus and body** of the stomach - They produce **pepsinogen**, the inactive precursor of the proteolytic enzyme pepsin, not gastrin

Question 1

Which of the following plant components is not fermented by gastrointestinal microorganisms?

Accepted Answer

Lignin

Answer

Cellulose

Answer

Hemicellulose

Answer

Pectin

Question 2

What is the primary reason for the detergent action of bile salts?

Accepted Answer

Amphipathic nature

Answer

Hydrophobic properties

Answer

Acts as a zwitterion

Answer

None of the options

Question 3

Glucagon stimulates

Accepted Answer

Gluconeogenesis

Answer

Glycogenesis

Answer

Fatty acid synthesis

Answer

Glycolysis

Question 4

Anemia with reticulocytosis is seen in -

Accepted Answer

Hemolysis

Answer

Iron deficiency anemia

Answer

Vitamin B12 deficiency

Answer

Aplastic anemia

Question 5

Which of the following is a second-generation beta blocker?

Accepted Answer

Atenolol

Answer

Timolol

Answer

Nadolol

Answer

Propranolol

Question 6

Which of the following is the most accurate measure of Glomerular Filtration Rate (GFR)?

Accepted Answer

Iothalamate Clearance

Answer

Cystatin C

Answer

Serum creatinine

Answer

Creatinine Clearance

Question 7

Normal renal threshold for glucose is at plasma glucose level ?

Accepted Answer

200 mg/dl

Answer

100 mg/dl

Answer

300 mg/dl

Answer

400 mg/dl

Question 8

Which hormone is secreted by the "Delta cells" of the stomach?

Accepted Answer

Somatostatin

Answer

Cholecystokinin

Answer

Gastrin-releasing peptide

Answer

Secretin

Question 9

Sugars are primarily absorbed in?

Accepted Answer

Jejunum

Answer

Duodenum

Answer

Ascending colon

Answer

Ileum

Question 10

Which of the following is the primary site of gastrin production?

Accepted Answer

Gastric G cells

Answer

Gastric chief cells

Answer

Pancreas

Answer

Pituitary gland

NEET-PG 2013

Biochemistry

Internal Medicine

Pharmacology

Physiology