Biochemistry
1 questionsIf the percentage of thymine residues in DNA is 28%. What is the percentage of cytosine?
NEET-PG 2020 - Biochemistry NEET-PG Practice Questions and MCQs
Question 221: If the percentage of thymine residues in DNA is 28%. What is the percentage of cytosine?
- A. 36%
- B. 44%
- C. 22% (Correct Answer)
- D. 28%
Explanation: ***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.
Community Medicine
1 questionsWhich of the following is a Category A bioterrorism agent?
NEET-PG 2020 - Community Medicine NEET-PG Practice Questions and MCQs
Question 221: Which of the following is a Category A bioterrorism agent?
- A. Brucella
- B. Nipah virus
- C. Bacillus anthracis (Correct Answer)
- D. Coxiella
Explanation: ***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**.
Internal Medicine
2 questionsWhich of the following is not done in high altitude sickness?
Pulmonary Plethora is seen in -
NEET-PG 2020 - Internal Medicine NEET-PG Practice Questions and MCQs
Question 221: Which of the following is not done in high altitude sickness?
- A. Rapid descent
- B. Acetazolamide
- C. Oxygen
- D. Digoxin (Correct Answer)
Explanation: ***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].
Question 222: Pulmonary Plethora is seen in -
- A. Tricuspid Atresia
- B. TAPVC (Correct Answer)
- C. CoA
- D. TOF
Explanation: ***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].
Pathology
2 questionsLarge, irregular and friable vegetations are seen in?
Which of the following is a cause of Hirschsprung disease in a patient?
NEET-PG 2020 - Pathology NEET-PG Practice Questions and MCQs
Question 221: Large, irregular and friable vegetations are seen in?
- A. Infective endocarditis (Correct Answer)
- B. Rheumatic heart disease
- C. Non-bacterial thrombotic endocarditis (NBTE)
- D. Libman-sacks endocarditis
Explanation: ***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.
Question 222: Which of the following is a cause of Hirschsprung disease in a patient?
- A. Failure of involution of vitelline duct
- B. Failure of migration of neural crest cells (Correct Answer)
- C. Excessive peristalsis of the affected part of the gut
- D. Obstruction secondary to an infectious agent
Explanation: ***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.
Pediatrics
2 questionsA 2 year child presented with low grade fever and stridor. What is the likely diagnosis?
Which of the following, if normal, would be most significant in making PEM unlikely?
NEET-PG 2020 - Pediatrics NEET-PG Practice Questions and MCQs
Question 221: A 2 year child presented with low grade fever and stridor. What is the likely diagnosis?
- A. Acute Laryngotracheobronchitis (Correct Answer)
- B. Acute Bacterial Tracheitis
- C. Acute Epiglottitis
- D. Foreign Body aspiration
Explanation: ***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.
Question 222: Which of the following, if normal, would be most significant in making PEM unlikely?
- A. Lean body mass (Correct Answer)
- B. Serum Potassium
- C. Skin fold thickness
- D. Extracellular fluid (ECF)
Explanation: ***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.
Psychiatry
1 questionsWhich of the following dependence-causing drugs is most commonly abused worldwide?
NEET-PG 2020 - Psychiatry NEET-PG Practice Questions and MCQs
Question 221: Which of the following dependence-causing drugs is most commonly abused worldwide?
- A. Cannabis (Correct Answer)
- B. Heroin
- C. Amphetamine
- D. Cocaine
Explanation: ***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.
Surgery
1 questionsA 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?
NEET-PG 2020 - Surgery NEET-PG Practice Questions and MCQs
Question 221: 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?
- A. Plummer vinson syndrome
- B. Dysphagia Lusoria
- C. Laryngocoele
- D. Zenker's diverticulum (Correct Answer)
Explanation: ***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.