NEET-PG 2013 Practice Questions

Q: Ketone body formation without glycosuria is seen in ?

Starvation. ***Starvation*** - During **starvation**, the body depletes its **glycogen stores** and begins to break down **fat for energy**. This process leads to the production of **ketone bodies** (acetoacetate, beta-hydroxybutyrate, and acetone) as an alternative fuel source for the brain and other tissues. - Since there is no underlying problem with **insulin production** or action, blood glucose levels are typically low or normal, and therefore, **glycosuria** (glucose in the urine) is absent. *Diabetes mellitus* - In **uncontrolled diabetes mellitus**, especially Type 1, the body cannot effectively use **glucose** due to lack of insulin, leading to high blood glucose levels (**hyperglycemia**) and subsequently **glycosuria**. - The body then compensates by breaking down **fats**, leading to the formation of **ketone bodies** (**diabetic ketoacidosis**), which results in both **ketonuria** and **glycosuria**. *Diabetes insipidus* - **Diabetes insipidus** is a condition characterized by the inability to conserve water due to insufficient **antidiuretic hormone (ADH)** production or action, leading to excessive urination and thirst. - It does not involve abnormalities in **glucose metabolism** or **ketone body production** and therefore does not typically present with ketonuria or glycosuria. *Obesity* - While **obesity** can lead to **insulin resistance** and is a risk factor for Type 2 Diabetes, it does not directly cause **ketone body formation** in the absence of metabolic derangements such as those seen in uncontrolled diabetes or prolonged starvation. - In most cases of obesity without diabetes, **glucose metabolism** is still adequate enough to prevent significant reliance on **fat breakdown** for energy, meaning there is usually no ketonuria or glycosuria.

Q: Which of the following lipoproteins is most strongly associated with an increased risk of cardiovascular diseases and is commonly referred to as "bad cholesterol"?

LDL. ***LDL*** - **Low-density lipoprotein (LDL)** is commonly referred to as "bad" cholesterol because elevated levels are the **primary driver** of atherosclerotic plaque buildup in arterial walls. - LDL particles transport cholesterol from the liver to peripheral tissues; when present in excess, they infiltrate the arterial intima and undergo oxidative modification, triggering inflammatory responses that lead to atherosclerosis. - **Clinical significance:** LDL cholesterol is the primary target of lipid-lowering therapy in cardiovascular disease prevention. *VLDL* - **Very low-density lipoprotein (VLDL)** primarily transports endogenously synthesized **triglycerides** from the liver to peripheral tissues. - While elevated VLDL levels do contribute to cardiovascular risk (particularly through conversion to small, dense LDL particles), it is not the primary lipoprotein targeted in cardiovascular risk assessment. *Chylomicron* - **Chylomicrons** transport **dietary lipids** (triglycerides and cholesterol) from the intestines to tissues after meals. - They are rapidly cleared from circulation (half-life of 5-10 minutes) and are typically not present during fasting, making their contribution to chronic atherosclerotic plaque formation minimal. *Lp(a)* - **Lipoprotein(a) [Lp(a)]** is structurally similar to LDL but contains an additional apolipoprotein(a) molecule, which has homology to plasminogen and may interfere with fibrinolysis. - While Lp(a) is an independent cardiovascular risk factor, it is less commonly measured in routine clinical practice, and **LDL remains the cornerstone lipoprotein** for cardiovascular risk stratification and management.

Q: What is essential for the transfer of fatty acid across the mitochondrial membrane?

Carnitine. ***Carnitine*** - **Carnitine** is crucial for transporting **long-chain fatty acids** into the mitochondrial matrix for **beta-oxidation**. - It forms **acylcarnitine** by esterifying with fatty acids, allowing passage through the inner mitochondrial membrane via the **carnitine-acylcarnitine translocase**. *Creatinine* - **Creatinine** is a waste product formed from the breakdown of **creatine phosphate** in muscles and is excreted by the kidneys. - It serves as a marker for **kidney function** and has no role in fatty acid transport. *Biotin* - **Biotin** is a vitamin cofactor essential for **carboxylase enzymes**, including acetyl-CoA carboxylase in **fatty acid synthesis**. - While involved in lipid metabolism, it plays no role in the transport of fatty acids across mitochondrial membranes. *Creatine* - **Creatine** is a nitrogenous organic acid that helps supply energy to cells, primarily muscle, by facilitating the regeneration of **ATP**. - It plays no direct role in the facilitated transport of fatty acids across the mitochondrial membrane.

Q: Cryoprecipitate is useful in which of the following conditions?

Afibrinogenemia. ***Afibrinogenemia*** - Cryoprecipitate is rich in **fibrinogen**, factor VIII, factor XIII, von Willebrand factor, and fibronectin. It is the only blood product with a substantial concentration of fibrinogen. - **Afibrinogenemia** (or hypofibrinogenemia) is a condition characterized by low or absent levels of fibrinogen, a critical clotting factor that cryoprecipitate replaces effectively. *Hemophilia A* - Hemophilia A is a deficiency of **Factor VIII**. While cryoprecipitate contains factor VIII, **recombinant Factor VIII concentrates** are the preferred treatment due to better safety (reduced risk of viral transmission) and more precise dosing [1]. - Cryoprecipitate was historically used for Hemophilia A before the availability of safer, more specific factor concentrates [2]. *Thrombosthenia* - Thrombasthenia is a platelet function disorder characterized by defective **glycoprotein IIb/IIIa receptors** on platelets, leading to impaired platelet aggregation. - Cryoprecipitate does not contain platelets or factors that directly correct platelet function, making **platelet transfusions** the treatment of choice for severe bleeding in thrombasthenia. *Warfarin reversal* - Warfarin reversal is primarily achieved using **Vitamin K**, which restores levels of functional clotting factors II, VII, IX, and X. - For rapid reversal in emergencies, **prothrombin complex concentrate (PCC)** is preferred because it contains high concentrations of these vitamin K-dependent factors, addressing the primary deficiency caused by warfarin [1].

Q: Autoimmune thyroiditis is associated with all except which of the following?

Psoriasis. ***Psoriasis*** - Psoriasis is generally not associated with **autoimmune thyroiditis**, which is more commonly linked to other autoimmune disorders [1]. - Autoimmune thyroiditis does not typically result in the **skin changes** seen in psoriasis, distinguishing them clinically. *Sly* - Sly syndrome, while a genetic disorder, is not directly connected to **autoimmune thyroiditis**. - Conditions like Sly syndrome are metabolic and do not involve the autoimmune pathways typically seen in thyroiditis. *Myasthenia gravis* - Myasthenia gravis is an **autoimmune neuromuscular disorder** that can occur concurrently with thyroid diseases, particularly **thyroiditis** [1]. - Both conditions arise from **autoimmune processes**, making their association plausible [1]. *DM* - Diabetes Mellitus (DM), particularly Type 1, is often linked with other autoimmune diseases, including **autoimmune thyroiditis** [2]. - They share a common **autoimmune pathway**, making them more likely to co-occur than psoriasis [2].

Q: Which of the following is not a germ cell tumor?

Leydig cell tumor. ***Leydig cell tumor*** - Leydig cell tumors are classified as **sex-cord stromal tumors**, not germ cell tumors [1]. - These tumors are derived from **Leydig cells** which produce androgens, affecting the endocrine function rather than germ cell lineage [1]. *Endodermal sinus* - Endodermal sinus tumors, or **yolk sac tumors**, are indeed germ cell tumors characterized by **alpha-fetoprotein (AFP)** production [2]. - They typically arise in the testis or ovaries and are known for rapid growth and aggressiveness. *Embryonal carcinoma* - Embryonal carcinoma is a type of **germ cell tumor** commonly associated with elevated levels of **beta-hCG** [2]. - It primarily affects the testes in males and can occur in the ovaries, and it is known for its aggressive behavior. *Seminoma* - Seminomas are classic examples of **germ cell tumors**, noted for their sensitivity to radiation and chemotherapy [3]. - They usually present with **increased beta-hCG** levels and can coexist with non-seminomatous germ cell tumors [3]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 510-514. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lower Urinary Tract and Male Genital System, pp. 979-980. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lower Urinary Tract and Male Genital System, pp. 980-982.

Q: Which of the following statements is true regarding omalizumab?

All of the options. ***All of the options*** is correct because each statement is true: **Anti-IgE** - Omalizumab is a **humanized monoclonal antibody** that specifically targets and binds to **free IgE** in the circulation - By binding free IgE, it prevents IgE from attaching to **high-affinity receptors** on mast cells and basophils - This reduces the allergic cascade and prevents release of inflammatory mediators **Given subcutaneously** - Omalizumab is administered via **subcutaneous injection** only - Dosing is typically every **2 to 4 weeks** based on patient's body weight and baseline IgE levels - Not available in oral or intravenous formulations for asthma treatment **Used as add-on therapy in moderate to severe asthma prophylaxis** - FDA approved as **add-on maintenance treatment** for patients aged ≥6 years with **moderate to severe persistent allergic asthma** - Indicated when asthma is **inadequately controlled** with inhaled corticosteroids - Reduces frequency of asthma exacerbations and improves asthma control - Also approved for chronic spontaneous urticaria All three statements accurately describe omalizumab's mechanism, administration route, and clinical indication, making **"All of the options"** the correct answer.

Q: What is the mechanism of metabolism for alcohol, aspirin, and phenytoin at high doses?

Zero order kinetics. ***Zero order kinetics*** - This mechanism occurs when the **metabolic enzymes become saturated at high drug concentrations**, leading to a constant amount (not a constant percentage) of drug being eliminated per unit time. - Alcohol, aspirin, and phenytoin are examples of drugs that exhibit **saturable metabolism**, transitioning from first-order to zero-order kinetics at higher doses. *First pass kinetics* - This describes the **metabolism of a drug by the liver or gut wall enzymes before it reaches systemic circulation** after oral administration. - While relevant to the oral bioavailability of these drugs, it does not describe the specific mechanism of elimination at high doses. *First order kinetics* - In this mechanism, a **constant fraction or percentage of the drug is eliminated per unit of time**, meaning the rate of elimination is directly proportional to the drug concentration. - Most drugs follow first-order kinetics at therapeutic doses because metabolizing enzymes are not saturated. *Second order kinetics* - This is a **less common pharmacokinetic model** where the rate of elimination is proportional to the square of the drug concentration or involves two reactants. - It does not typically describe the common elimination patterns of most drugs, including alcohol, aspirin, and phenytoin.

Q: Which of the following develop first during dependence of a substance ?

Psychological dependence. ***Psychological dependence*** - **Psychological dependence** often develops first, characterized by an emotional need for the substance to experience pleasure or avoid discomfort. - This involves a strong **craving** and compulsive drug-seeking behavior despite negative consequences, driven by the substance's effect on brain reward pathways. *Tolerance* - **Tolerance** means that increasing doses of the substance are required to achieve the same effect previously achieved with lower doses. - While it often develops early in substance use, the initial "need" to use the substance is often psychological before physiological adaptations occur. *Physical dependence* - **Physical dependence** describes the body's physiological adaptation to the substance, leading to withdrawal symptoms if use is stopped or reduced. - It typically develops after consistent, prolonged use and is usually preceded by psychological dependence and often tolerance. *Withdrawal symptoms* - **Withdrawal symptoms** are the physiological and psychological signs that occur when a dependent person stops or drastically reduces their substance intake. - These are a direct manifestation of physical dependence and thus develop once physical dependence has been established.

Question 1

Ketone body formation without glycosuria is seen in ?

Accepted Answer

Starvation

Answer

Diabetes mellitus

Answer

Diabetes insipidus

Answer

Obesity

Question 2

Which of the following lipoproteins is most strongly associated with an increased risk of cardiovascular diseases and is commonly referred to as "bad cholesterol"?

Accepted Answer

LDL

Answer

VLDL

Answer

Chylomicron

Answer

Lp (a)

Question 3

What is essential for the transfer of fatty acid across the mitochondrial membrane?

Accepted Answer

Carnitine

Answer

Creatinine

Answer

Biotin

Answer

Creatine

Question 4

What is the process of Hofmann elimination in organic chemistry?

Accepted Answer

E2 elimination reaction producing the least substituted alkene

Answer

E1 elimination reaction favoring tertiary substrates

Answer

SN1 substitution reaction with carbocation intermediate

Answer

SN2 substitution reaction with inversion of configuration

Question 5

Cryoprecipitate is useful in which of the following conditions?

Accepted Answer

Afibrinogenemia

Answer

Hemophilia A

Answer

Thrombosthenia

Answer

Warfarin reversal

Question 6

Autoimmune thyroiditis is associated with all except which of the following?

Accepted Answer

Psoriasis

Answer

DM

Answer

Myasthenia gravis

Answer

SLE

Question 7

Which of the following is not a germ cell tumor?

Accepted Answer

Leydig cell tumor

Answer

Embryonal carcinoma

Answer

Endodermal sinus

Answer

Seminoma

Question 8

Which of the following statements is true regarding omalizumab?

Accepted Answer

All of the options

Answer

Anti-IgE

Answer

Given subcutaneously

Answer

Used as add-on therapy in moderate to severe asthma prophylaxis

Question 9

What is the mechanism of metabolism for alcohol, aspirin, and phenytoin at high doses?

Accepted Answer

Zero order kinetics

Answer

First pass kinetics

Answer

First order kinetics

Answer

Second order kinetics

Question 10

Which of the following develop first during dependence of a substance ?

Accepted Answer

Psychological dependence

Answer

Tolerance

Answer

Physical dependence

Answer

Withdrawal symptoms

NEET-PG 2013

Biochemistry

Internal Medicine

Pathology

Pharmacology

Psychiatry