NEET-PG 2020 Practice Questions

Q: Apolipoprotein B-48 is made by which process?

RNA editing. ***RNA editing*** - Apolipoprotein B-48 is synthesized from ApoB-100 mRNA through a process called **RNA editing** (specifically ApoB mRNA editing) - This involves a **cytidine deaminase enzyme (APOBEC-1)** that converts cytidine to uridine at position 6666, changing a glutamine codon (CAA) to a premature stop codon (UAA) in the small intestine - This results in a truncated protein that is 48% the length of ApoB-100 - ApoB-48 is produced in the **intestine**, while ApoB-100 (unedited) is produced in the **liver** *DNA editing* - DNA editing refers to permanent modifications in the DNA sequence itself - The ApoB gene remains unchanged; only the mRNA transcript is edited in intestinal cells - This is not the mechanism for producing ApoB-48 *RNA alternate splicing* - Alternative splicing involves selecting different combinations of exons from pre-mRNA to produce multiple mRNA isoforms - This process creates different protein variants through exon inclusion/exclusion - ApoB-48 production does not involve alternative splicing but rather direct nucleotide modification (C to U) within the coding sequence *RNA interference* - RNA interference (RNAi) is a biological process involving small RNA molecules (siRNA, miRNA) that silence gene expression - RNAi typically degrades mRNA or blocks translation - This process is not involved in generating a truncated protein like ApoB-48 from the same mRNA transcript

Q: A child was fed on a staple diet of maize for a long time. Which of the following vitamin may get deficient in his body?

Niacin (Vitamin B3). ***Niacin (Vitamin B3)*** - Maize is deficient in tryptophan (an amino acid that can be converted to **niacin**) and contains niacin in a bound form (**niacytin**) that is not bioavailable. - A staple diet of maize without adequate supplementation can lead to **pellagra**, characterized by the classic triad of dermatitis, diarrhea, and dementia (3 D's). - This is particularly common in populations relying heavily on untreated maize as a staple food. *Thiamine (Vitamin B1)* - While polishing rice can remove thiamine, maize itself is not primarily associated with **thiamine deficiency** as a staple. - **Beriberi** (thiamine deficiency) presents with neurological and cardiovascular symptoms (wet and dry beriberi), distinct from pellagra. *Vitamin B6 (Pyridoxine)* - Deficiency of **pyridoxine** is uncommon with maize-based diets unless there are other contributing factors like drug interactions (e.g., isoniazid). - Symptoms include peripheral neuropathy, seborrheic dermatitis, and sideroblastic anemia, which are not directly linked to a maize staple diet. *Cobalamin (Vitamin B12)* - **Vitamin B12** is found primarily in animal products, so a vegetarian or vegan diet poses a risk for deficiency, not specifically a maize-based diet. - Deficiency leads to megaloblastic anemia and neurological damage (subacute combined degeneration), unrelated to maize's nutritional profile.

Q: Which of the following is true about non-competitive inhibition?

Km remains same, Vmax decreases. ***Km remains same, Vmax decreases*** - In **non-competitive inhibition**, the inhibitor binds to an allosteric site on the enzyme, altering its conformation, thereby **reducing its catalytic efficiency**. - This binding does not affect the **enzyme's affinity for the substrate (Km remains the same)**, but it **reduces the maximum reaction rate (Vmax decreases)** because fewer enzyme molecules are able to perform catalysis per unit time. *Km increases, Vmax remains same* - This describes **competitive inhibition**, where the inhibitor competes with the substrate for the enzyme's active site. - While it **increases the apparent Km** (more substrate needed to reach half Vmax), **Vmax remains unchanged** as high substrate concentrations can overcome the inhibition. *Km decreases, Vmax increases* - This scenario would imply an activation rather than inhibition, where both enzyme affinity and catalytic efficiency are enhanced. - This is not characteristic of any standard **enzyme inhibition mechanism**. *Km increases, Vmax increases* - This combination is not observed in any typical **enzyme inhibition pattern**. - An increase in **Vmax** implies enhanced catalytic activity, while an increase in **Km** suggests reduced substrate affinity, which are contradictory effects for a single inhibitor.

Q: All are true regarding Japanese encephalitis disease except:

Man acts as reservoir. ***Man acts as reservoir*** - Humans are considered **dead-end hosts** for Japanese encephalitis; they do not develop sufficiently high viremia to transmit the virus back to mosquitoes. - The primary reservoirs for the Japanese encephalitis virus are **pigs** and **wading birds**. *Pig vaccination control transmission* - **Vaccinating pigs** is an effective strategy to control Japanese encephalitis transmission because pigs are significant amplifier hosts, producing high levels of viremia. - By reducing the viral load in the pig population, pig vaccination helps **break the transmission cycle** between mosquitoes and humans. *Vector is Culex vishnui* - The primary vector involved in the transmission of Japanese encephalitis is indeed **Culex mosquitoes**, with **Culex vishnui complex** being a significant group responsible for its spread in many endemic regions. - These mosquitoes primarily breed in **rice paddies** and other stagnant water sources, which are common in areas where the disease is prevalent. *None of the options are true* - This option is incorrect because the statements regarding **pig vaccination** and the **Culex vishnui** vector are true in the context of Japanese encephalitis. - The initial premise that "Man acts as reservoir" is the false statement, making it the correct answer to the "except" question.

Q: A patient posted for Lap Cholecystectomy had drug eluting stent placed two years back. Patient has no symptoms since then. Which of the following set of investigation should be done in this patient?

ECG, CBC, Stress echocardiography. **ECG, CBC, Stress echocardiography** - A patient with a **drug-eluting stent (DES)** placed two years prior, who is now asymptomatic, typically requires a **non-invasive cardiac assessment** before surgery. [1] - **Stress echocardiography** is an appropriate investigation to assess for inducible ischemia in an asymptomatic patient with a history of DES, especially when determining readiness for non-cardiac surgery. [1] *Coronary angiography, Thallium scan* - **Coronary angiography** is an invasive procedure and is generally not indicated for asymptomatic patients two years post-DES unless there are new symptoms or high-risk findings on non-invasive tests. [2] - A **Thallium scan** (myocardial perfusion scintigraphy) is a valid stress test, but **stress echocardiography** provides similar information regarding ischemia and ventricular function without radiation exposure. [1] *ECG, CBC, Coronary angiography* - While **ECG** and **CBC** are standard preoperative tests, **coronary angiography** is an invasive procedure and is not the first-line investigation for an asymptomatic patient two years post-DES without other indications. [2] - The patient's asymptomatic status suggests that invasive testing is not immediately warranted for surgical clearance. *ECG, CBC, Stress echocardiography, coronary angiography* - Performing both **stress echocardiography** and **coronary angiography** in an asymptomatic patient two years after DES placement is **redundant** and subjects the patient to an unnecessary invasive procedure. [1], [2] - The results of a non-invasive stress test like stress echocardiography would guide the need for any further invasive intervention.

Q: In comparison to a normal healthy person, in the evening time, which of these will have an elevated ACTH as well as elevated Cortisol?

Cushing's disease. **_Cushing's disease_** * In **Cushing's disease**, there is an **ACTH-producing pituitary adenoma** that leads to excessive ACTH secretion, which in turn stimulates the adrenal glands to produce high levels of cortisol. * This results in **chronically elevated cortisol levels** throughout the day, including the evening, and an inappropriately elevated ACTH due to increased production from the pituitary. *Addison's disease* * **Addison's disease** is characterized by **primary adrenal insufficiency**, meaning the adrenal glands cannot produce sufficient cortisol despite adequate ACTH stimulation. * While ACTH would be significantly **elevated** due to a lack of negative feedback from cortisol, the **cortisol levels would be low** or normal in response to the adrenal gland dysfunction. *Transient state after exercise (evening time)* * During and immediately after **intense exercise**, both ACTH and cortisol levels can transiently increase as part of the body's stress response. * However, these elevations are typically **transient** and would not represent a sustained, pathologically elevated state in the evening in the same way as Cushing's disease, and levels would usually normalize relatively quickly. *Normal healthy person (evening time)* * In a normal healthy person, ACTH and cortisol levels exhibit a **diurnal rhythm**, with the highest levels in the morning and the lowest levels in the late evening/night. * Therefore, in the evening, both **ACTH and cortisol levels would naturally be low** as part of the physiological circadian rhythm, not elevated.

Q: A person was brought to emergency department and was diagnosed with Supra ventricular tachycardia and suddenly he became unstable. What is the next line of management?

DC Cardioversion. ***DC Cardioversion*** - For **unstable supraventricular tachycardia (SVT)**, immediate **direct current (DC) cardioversion** is the definitive treatment to restore sinus rhythm. - Instability in SVT includes symptoms like hypotension, altered mental status, signs of shock, ischemic chest discomfort, or acute heart failure. *Intravenous ibutilide* - **Ibutilide** is an antiarrhythmic drug used for pharmacological cardioversion of recent-onset atrial fibrillation or flutter, but not typically for unstable SVT. - While it can convert certain supraventricular arrhythmias, it is generally reserved for **stable patients** and takes longer to act than immediate electrical cardioversion. *Intravenous Diltiazem* - **Diltiazem** is a calcium channel blocker used to control ventricular rate in **stable SVT**, atrial fibrillation, or flutter [1]. - It is contraindicated in unstable patients as it can further depress cardiac contractility and worsen hypotension [2]. *Intravenous Flecainide* - **Flecainide** is a class Ic antiarrhythmic drug used to maintain sinus rhythm in patients with supraventricular arrhythmias, including SVT. - It also takes time to act and is used in **stable patients** without structural heart disease, not in emergency unstable situations where immediate rhythm conversion is required.

Q: In current obstetrics practice, what is the best test for monitoring sensitized Rh negative mother?

Middle cerebral artery Doppler wave forms. ***Middle cerebral artery Doppler wave forms*** - This is currently the most widely accepted and **non-invasive** method for monitoring **fetal anemia** in Rh-sensitized pregnancies. - An increase in the **peak systolic velocity (PSV)** in the middle cerebral artery indicates that the fetus is increasing cardiac output to compensate for a reduced oxygen-carrying capacity due to anemia. *Biophysical profile* - The biophysical profile assesses various fetal parameters like **movement**, **tone**, **breathing**, and **amniotic fluid volume**, which are often altered late in the course of severe fetal anemia. - It is a **less sensitive** indicator of early or moderate fetal anemia compared to MCA Doppler. *Amniotic fluid spectrophotometry* - This method measures the **bilirubin levels** in amniotic fluid, which correlates with the severity of hemolysis. - It is an **invasive procedure** (amniocentesis) and has largely been replaced by non-invasive MCA Doppler due to associated risks and better predictive value of Doppler. *Fetal blood sampling* - Fetal blood sampling (cordocentesis) provides a direct measurement of **fetal hemoglobin** and other blood parameters. - While definitive, it is a **highly invasive procedure** with significant risks, reserved primarily for confirmation of severe anemia or for direct transfusion, not for routine monitoring.

Q: Which of the following is NOT used as an emergency contraceptive?

Danazol. ***Danazol*** - **Danazol** is an **androgen derivative** primarily used to treat **endometriosis** and **fibrocystic breast disease**, not for emergency contraception. - Its mechanism involves suppressing **ovarian function** and creating an anovulatory state, which is not suitable for immediate post-coital intervention. *RU 486* - **RU 486 (Mifepristone)** is a **progesterone receptor modulator** that can be used as an emergency contraceptive, especially at higher doses. - It acts by **blocking progesterone receptors**, preventing implantation or inducing abortion if pregnancy has already occurred. *Copper T* - The **Copper T (intrauterine device - IUD)** is a highly effective method of emergency contraception if inserted within 5 days of unprotected intercourse. - It works by causing a **spermicidal effect** and preventing fertilization or implantation by inducing an inflammatory reaction in the uterus. *OCpill* - **OCPills (oral contraceptive pills)**, usually a combination of estrogen and progestin, can be used as emergency contraception when taken in higher doses. - This method, known as the **Yuzpe regimen**, involves taking two doses of combined oral contraceptives within 72 hours of unprotected intercourse to inhibit ovulation or fertilization.

Q: Management of RCC less than 4 cm in size:

Partial nephrectomy. ***Correct: Partial nephrectomy*** - For **renal cell carcinoma (RCC) less than 4 cm (T1a)**, partial nephrectomy is the **gold standard** as it offers equivalent oncological outcomes to radical nephrectomy while preserving renal function. - This approach minimizes the risk of **chronic kidney disease** and its associated complications without compromising cancer control for appropriately selected smaller tumors. - **Nephron-sparing surgery** is now the preferred approach per EAU and AUA guidelines for small renal masses. *Incorrect: Surgery followed by chemotherapy* - While surgery is the primary treatment, **adjuvant chemotherapy** is generally **not effective** for localized RCC and is not routinely recommended for small tumors. - Systemic therapies are typically reserved for **advanced or metastatic RCC**, or in specific clinical trials. *Incorrect: Radical nephrectomy* - This involves removing the entire kidney, which is typically reserved for **larger tumors (T1b and above)**, centrally located tumors, or those with significant renal parenchymal involvement. - For tumors under 4 cm, radical nephrectomy leads to **unnecessary loss of renal function** compared to partial nephrectomy. *Incorrect: Chemotherapy* - **RCC is notoriously chemoresistant**, meaning traditional chemotherapy drugs have very limited efficacy in treating this cancer. - Chemotherapy alone is **not a primary treatment modality** for localized RCC due to its poor response rates in this cancer type.

Question 1

Apolipoprotein B-48 is made by which process?

Accepted Answer

RNA editing

Answer

DNA editing

Answer

RNA alternate splicing

Answer

RNA interference

Question 2

A child was fed on a staple diet of maize for a long time. Which of the following vitamin may get deficient in his body?

Accepted Answer

Niacin (Vitamin B3)

Answer

Thiamine (Vitamin B1)

Answer

Vitamin B6 (Pyridoxine)

Answer

Cobalamin (Vitamin B12)

Question 3

Which of the following is true about non-competitive inhibition?

Accepted Answer

Km remains same, Vmax decreases

Answer

Km increases, Vmax remains same

Answer

Km decreases, Vmax increases

Answer

Km increases, Vmax increases

Question 4

All are true regarding Japanese encephalitis disease except:

Accepted Answer

Man acts as reservoir

Answer

Pig vaccination control transmission

Answer

Vector is Culex vishnui

Answer

None of the options are true

Question 5

A patient posted for Lap Cholecystectomy had drug eluting stent placed two years back. Patient has no symptoms since then. Which of the following set of investigation should be done in this patient?

Accepted Answer

ECG, CBC, Stress echocardiography

Answer

Coronary angiography, Thallium scan

Answer

ECG, CBC, Coronary angiography

Answer

ECG, CBC, Stress echocardiography, coronary angiography

Question 6

In comparison to a normal healthy person, in the evening time, which of these will have an elevated ACTH as well as elevated Cortisol?

Accepted Answer

Cushing's disease

Answer

Addison's disease

Answer

Transient state after exercise (evening time)

Answer

Normal healthy person (evening time)

Question 7

A person was brought to emergency department and was diagnosed with Supra ventricular tachycardia and suddenly he became unstable. What is the next line of management?

Accepted Answer

DC Cardioversion

Answer

Intravenous ibutilide

Answer

Intravenous Diltiazem

Answer

Intravenous Flecainide

Question 8

In current obstetrics practice, what is the best test for monitoring sensitized Rh negative mother?

Accepted Answer

Middle cerebral artery Doppler wave forms

Answer

Biophysical profile

Answer

Amniotic fluid spectrophotometry

Answer

Fetal blood sampling

Question 9

Which of the following is NOT used as an emergency contraceptive?

Accepted Answer

Danazol

Answer

RU 486

Answer

Copper T

Answer

OCpill

Question 10

Management of RCC less than 4 cm in size:

Accepted Answer

Partial nephrectomy

Answer

Surgery followed by chemotherapy

Answer

Radical nephrectomy

Answer

Chemotherapy

NEET-PG 2020

Biochemistry

Community Medicine

Internal Medicine

Obstetrics and Gynecology

Surgery