NEET-PG 2020 Practice Questions

Q: If the percentage of thymine residues in DNA is 28%. What is the percentage of cytosine?

22%. ***22%*** - According to **Chargaff's rules**, in a DNA molecule, the amount of **adenine (A) is equal to the amount of thymine (T)**, and the amount of **guanine (G) is equal to the amount of cytosine (C)**. - If thymine (T) is 28%, then adenine (A) is also 28%, making a total of 56% for A+T. The remaining 44% (100% - 56%) is split equally between guanine and cytosine, so cytosine (C) is 22%. *36%* - This percentage would be plausible if the sum of adenine and thymine were 28%, which is incorrect as A and T are equal and their sum would thus be 56%. - This value does not adhere to the principle of **base pairing complementarity** and the total percentage of all bases summing to 100%. *44%* - This would be the combined percentage of guanine and cytosine, not the percentage of cytosine alone. - If cytosine were 44%, then guanine would also be 44%, leading to a total of 88% for G+C, which is inconsistent with T being 28%. *28%* - This is the percentage of thymine, and by **Chargaff's rules**, it would also be the percentage of adenine, not cytosine. - Cytosine percentages are derived from the remaining proportion of bases after accounting for adenine and thymine.

Q: A 70 year old patient presented with history of fever, repeated aspiration and coughing in the night. On examination there is a swelling on left side of neck which produces gurgling sound on compression. Following is the barium swallow study of the patient. What is the most likely diagnosis?

Zenker's diverticulum. ***Zenker's diverticulum*** - The patient's symptoms of **fever**, **repeated aspiration**, and **coughing at night** are classic for a Zenker's diverticulum, particularly in an older patient. - The presence of a **neck swelling** producing a **gurgling sound on compression** (Boyce's sign) is highly indicative of a Zenker's diverticulum, which is essentially a pharyngeal pouch. The barium swallow image likely shows contrast pooling in such a pouch. *Plummer Vinson syndrome* - Characterized by **dysphagia**, **iron-deficiency anemia**, and **esophageal webs**. - While it causes dysphagia, it does not typically present with a gurgling neck swelling or significant aspiration as described. *Dysphagia Lusoria* - This is a rare condition caused by an **aberrant right subclavian artery** compressing the esophagus. - It primarily causes dysphagia due to extrinsic compression, without the associated neck swelling, gurgling sound, or significant aspiration risk from food pooling within a diverticulum. *Laryngocoele* - A laryngocele is an **abnormal sac** or pouch that arises from the **laryngeal ventricle** and may extend externally, presenting as a neck swelling. - While it can cause a neck swelling, it is **air-filled**, not fluid or food-filled, and therefore would not typically produce a gurgling sound on compression or be clearly visible on a barium swallow as a contrast-filled pouch like in the image provided.

Q: Which of the following is not done in high altitude sickness?

Digoxin. ***Digoxin*** - **Digoxin** is a cardiac glycoside used for heart conditions like **atrial fibrillation** and **heart failure**. It has no role in the treatment of high altitude sickness. - Its primary actions are to increase **myocardial contractility** and decrease heart rate, which are not beneficial in addressing the hypobaric hypoxia of high altitude. *Rapid descent* - **Rapid descent** is the most effective and often immediate treatment for severe forms of high altitude sickness, such as **High Altitude Cerebral Edema (HACE)** or **High Altitude Pulmonary Edema (HAPE)** [2]. - It involves moving the affected individual to a significantly lower altitude to alleviate the effects of **hypoxia** [2]. *Acetazolamide* - **Acetazolamide** is a **carbonic anhydrase inhibitor** commonly used for the prevention and treatment of high altitude sickness [2]. - It works by inducing a **metabolic acidosis**, which stimulates **respiration** and increases **oxygenation**. *Oxygen* - Administering **supplemental oxygen** is a crucial treatment for high altitude sickness, especially in more severe cases [2]. - It directly counteracts the **hypoxia** experienced at high altitudes, improving symptoms and preventing progression [1], [2].

Q: Pulmonary Plethora is seen in -

TAPVC. ***TAPVC*** - **Total Anomalous Pulmonary Venous Connection (TAPVC)** leads to all pulmonary veins draining into the systemic circulation, causing a left-to-right shunt at the atrial level back into the right atrium. - This persistent shunting results in increased blood flow to the lungs, manifesting as **pulmonary plethora** on chest X-ray due to engorged pulmonary vessels [3]. *Tricuspid Atresia* - **Tricuspid atresia** results in an absence of the tricuspid valve, severely limiting blood flow from the right atrium to the right ventricle. - This condition typically leads to **pulmonary oligemia** (reduced blood flow to the lungs), not pulmonary plethora. *CoA* - **Coarctation of the aorta (CoA)** is a narrowing of the aorta, typically distal to the left subclavian artery [2]. - While it can lead to complications like heart failure, it generally does not directly cause **pulmonary plethora** unless there are associated shunts. *TOF* - **Tetralogy of Fallot (TOF)** is characterized by four defects: ventricular septal defect, pulmonary stenosis, overriding aorta, and right ventricular hypertrophy [1]. - The most significant hemodynamic feature is **pulmonary stenosis**, which reduces blood flow to the lungs, leading to **pulmonary oligemia**, often described as a "boot-shaped" heart on X-ray [1].

Q: Which of the following is a Category A bioterrorism agent?

Bacillus anthracis. ***Bacillus anthracis*** - **_Bacillus anthracis_** (causing anthrax) is a classic example of a **Category A bioterrorism agent** due to its high mortality, ease of dissemination, and potential for major public health impact. - Category A agents are considered the **highest priority** because they pose a significant risk to national security. *Brucella* - **_Brucella_** species are classified as **Category B bioterrorism agents**. - They are moderately easy to disseminate and can cause moderate morbidity but generally have a **low mortality rate**. *Nipah virus* - **Nipah virus** is categorized as a **Category C bioterrorism agent**. - These are emerging pathogens that could be engineered for mass dissemination in the future, but their current risk is lower than Category A or B. *Coxiella* - **_Coxiella burnetii_** (causing Q fever) is classified as a **Category B bioterrorism agent**. - It is relatively easy to disseminate and can cause high morbidity but has a **low mortality rate**.

Q: Large, irregular and friable vegetations are seen in?

Infective endocarditis. ***Infective endocarditis*** - **Large, irregular, and friable vegetations** are characteristic of infective endocarditis, formed by a mesh of **platelets, fibrin, microorganisms**, and inflammatory cells [1]. - These vegetations can lead to serious complications such as **embolization** and destruction of heart valves [2]. *Rheumatic heart disease* - Characterized by **small, warty vegetations** that are typically located on the lines of closure of the heart valves, not large and friable [1]. - These vegetations are sterile and result from inflammation and fibrin deposition, usually not involving active microbial infection. *Non-bacterial thrombotic endocarditis (NBTE)* - Features **small, sterile vegetations** composed of fibrin and platelets, often found on previously undamaged valves [1]. - These vegetations are typically **firm** and non-inflammatory, distinct from the friable and infected vegetations of infective endocarditis. *Libman-sacks endocarditis* - Manifests as **sterile, verrucous vegetations** that can occur on either side of the valve leaflets (aortic or mitral) in patients with **systemic lupus erythematosus (SLE)** [1]. - While they can be large, they are usually not described as friable in the same manner as infective endocarditis and are sterile. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, p. 568. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Cardiovascular Disease, pp. 295-296.

Q: Which of the following is a cause of Hirschsprung disease in a patient?

Failure of migration of neural crest cells. ***Failure of migration of neural crest cells*** - Hirschsprung disease is characterized by the absence of **ganglion cells** (Auerbach and Meissner plexuses) in the distal colon [1]. - This aganglionosis results from the failure of **neural crest cells** to migrate completely from the esophagus to the anus during embryonic development [1]. *Failure of involution of vitelline duct* - This condition is associated with **Meckel's diverticulum**, which is a remnant of the vitelline duct, not Hirschsprung disease. - **Meckel's diverticulum** can cause symptoms like GI bleeding or obstruction, but it does not involve aganglionosis of the colon. *Excessive peristalsis of the affected part of the gut* - Hirschsprung disease is characterized by a **lack of peristalsis** in the aganglionic segment, leading to functional obstruction [1]. - The healthy, proximal colon may show increased peristalsis in an attempt to overcome the obstruction, but the affected segment itself is aperistaltic. *Obstruction secondary to an infectious agent* - Obstruction due to an infectious agent is typically related to **inflammatory processes** or strictures caused by infections (e.g., severe colitis). - This mechanism of obstruction does not involve the **developmental anomaly** of missing ganglion cells, which is central to Hirschsprung disease. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 94-95.

Q: A 2 year child presented with low grade fever and stridor. What is the likely diagnosis?

Acute Laryngotracheobronchitis. ***Acute Laryngotracheobronchitis*** - The combination of **low-grade fever** and **stridor** in a 2-year-old child strongly suggests **croup**, which is medically known as acute laryngotracheobronchitis. - Croup is characterized by **inflammation** of the larynx, trachea, and bronchi, often presenting with a **barking cough** and inspiratory stridor. The X-ray image would show the characteristic **steeple sign**. *Acute Bacterial Tracheitis* - This is a more severe bacterial infection that can present with stridor but typically shows **higher fever**, **toxic appearance**, and rapid clinical deterioration. - Unlike croup, bacterial tracheitis patients appear **more ill** and may have **purulent secretions** requiring more aggressive management. *Acute Epiglottitis* - A serious condition characterized by **rapid onset of high fever**, **dysphagia**, drooling, and a **"tripod" position**, which are not indicated by the given symptoms. - The stridor in epiglottitis is typically quieter and may indicate more severe airway obstruction compared to the characteristic stridor of croup. *Foreign Body aspiration* - While foreign body aspiration can cause stridor, it is typically an **acute event** with a sudden onset of choking, coughing, and respiratory distress. - There is no mention of a choking episode or sudden onset, and a low-grade fever is less typical for an uncomplicated foreign body aspiration.

Q: Which of the following, if normal, would be most significant in making PEM unlikely?

Lean body mass. ***Lean body mass*** - A normal **lean body mass** indicates adequate muscle and organ tissue, which is the primary component affected by **Protein-Energy Malnutrition (PEM)**. - Maintaining normal lean body mass despite potential weight loss makes significant PEM, especially the **marasmic type**, less likely. *Extracellular fluid (ECF)* - **Extracellular fluid (ECF)** can be normal or even increased in cases of **edematous PEM** (kwashiorkor) due to decreased oncotic pressure, making it an unreliable indicator for excluding PEM. - Normal ECF does not rule out the depletion of protein, fat, and muscle mass that characterizes PEM. *Serum Potassium* - **Serum potassium** levels can be normal or abnormal (low or high) in PEM depending on hydration status, renal function, and refeeding syndrome, making it a non-specific indicator for excluding the condition. - It does not directly reflect the overall **nutritional status** or body composition changes seen in PEM. *Skin fold thickness* - **Skin fold thickness** measures subcutaneous fat stores, which can be normal or even preserved in some forms of PEM, particularly **kwashiorkor**, even when severe protein deficiency exists. - While reduced skin fold thickness suggests **marasmus**, a normal value does not conclusively rule out **protein deficiency** or other forms of PEM.

Q: Which of the following dependence-causing drugs is most commonly abused worldwide?

Cannabis. ***Cannabis*** - **Cannabis** is the most widely cultivated and consumed illicit drug globally, with the highest prevalence of past-year use. - Its widespread availability, relatively lower perception of harm compared to other drugs, and varied forms of consumption (smoking, edibles) contribute to its extensive abuse. *Heroin* - **Heroin** is a highly addictive opioid that causes severe physical dependence and withdrawal symptoms, but its global prevalence is significantly lower than that of cannabis. - Its high cost, illicit nature, and significant health risks, including overdose, limit its abuse to a smaller, though critically affected, population. *Amphetamine* - **Amphetamines**, including methamphetamine, are potent central nervous system stimulants with a significant abuse potential, leading to psycho-behavioral and physical dependence. - While prevalent in certain regions and among specific populations, their overall global abuse statistics are lower than those for cannabis. *Cocaine* - **Cocaine** is a powerful stimulant derived from the coca plant, known for its strong psychological dependence and significant health consequences. - Its abuse is concentrated in specific geographical areas and demographic groups, making its global prevalence of abuse lower than that of cannabis.

Question 1

If the percentage of thymine residues in DNA is 28%. What is the percentage of cytosine?

Accepted Answer

22%

Answer

36%

Answer

44%

Answer

28%

Question 2

A 70 year old patient presented with history of fever, repeated aspiration and coughing in the night. On examination there is a swelling on left side of neck which produces gurgling sound on compression. Following is the barium swallow study of the patient. What is the most likely diagnosis?

Accepted Answer

Zenker's diverticulum

Answer

Plummer vinson syndrome

Answer

Dysphagia Lusoria

Answer

Laryngocoele

Question 3

Which of the following is not done in high altitude sickness?

Accepted Answer

Digoxin

Answer

Rapid descent

Answer

Acetazolamide

Answer

Oxygen

Question 4

Pulmonary Plethora is seen in -

Accepted Answer

TAPVC

Answer

Tricuspid Atresia

Answer

CoA

Answer

TOF

Question 5

Which of the following is a Category A bioterrorism agent?

Accepted Answer

Bacillus anthracis

Answer

Brucella

Answer

Nipah virus

Answer

Coxiella

Question 6

Large, irregular and friable vegetations are seen in?

Accepted Answer

Infective endocarditis

Answer

Rheumatic heart disease

Answer

Non-bacterial thrombotic endocarditis (NBTE)

Answer

Libman-sacks endocarditis

Question 7

Which of the following is a cause of Hirschsprung disease in a patient?

Accepted Answer

Failure of migration of neural crest cells

Answer

Failure of involution of vitelline duct

Answer

Excessive peristalsis of the affected part of the gut

Answer

Obstruction secondary to an infectious agent

Question 8

A 2 year child presented with low grade fever and stridor. What is the likely diagnosis?

Accepted Answer

Acute Laryngotracheobronchitis

Answer

Acute Bacterial Tracheitis

Answer

Acute Epiglottitis

Answer

Foreign Body aspiration

Question 9

Which of the following, if normal, would be most significant in making PEM unlikely?

Accepted Answer

Lean body mass

Answer

Serum Potassium

Answer

Skin fold thickness

Answer

Extracellular fluid (ECF)

Question 10

Which of the following dependence-causing drugs is most commonly abused worldwide?

Accepted Answer

Cannabis

Answer

Heroin

Answer

Amphetamine

Answer

Cocaine

NEET-PG 2020

Biochemistry

ENT

Internal Medicine

Microbiology

Pathology

Pediatrics

Psychiatry