Biochemistry
4 questionsWhich of the following statements about Niemann-Pick disease is false?
Which protein does the domain of plasminogen resemble?
Which of the following stimulates Acetyl CoA Carboxylase?
HDL is called good cholesterol because -
NEET-PG 2015 - Biochemistry NEET-PG Practice Questions and MCQs
Question 571: Which of the following statements about Niemann-Pick disease is false?
- A. Due to deficiency of sphingomyelinase.
- B. CNS symptoms are present in type A.
- C. Type B Niemann-Pick disease is characterized by severe neurological symptoms. (Correct Answer)
- D. Histiocytes show PAS positive inclusions, and Type A is more severe.
Explanation: ***Type B Niemann-Pick disease is characterized by severe neurological symptoms.*** - This statement is **false** because **Type B Niemann-Pick disease** generally presents with **visceral involvement** (e.g., hepatosplenomegaly, lung disease) with **minimal to no neurological symptoms**. - **Severe neurological symptoms** are characteristic of **Type A Niemann-Pick disease**, which involves widespread CNS degeneration and a more rapidly progressive course. *Due to deficiency of sphingomyelinase.* - This statement is **true**. - Niemann-Pick disease (Types A and B) is caused by a deficiency of the enzyme **acid sphingomyelinase**, leading to the accumulation of sphingomyelin within lysosomes, particularly in macrophages. *CNS symptoms are present in type A.* - This statement is **true**. - **Type A Niemann-Pick disease** is the most severe form and is characterized by significant **neurodegeneration** in addition to visceral involvement. - Patients typically present with **developmental regression**, **ataxia**, and **spasticity** due to extensive sphingomyelin deposition in the central nervous system. *Histiocytes show PAS positive inclusions, and Type A is more severe.* - This statement is **true**. - The characteristic "foam cells" (lipid-laden macrophages/histiocytes) found in tissues of Niemann-Pick patients stain positive with **periodic acid–Schiff (PAS)** due to accumulated sphingomyelin. - **Type A Niemann-Pick disease** is indeed the most severe form, with a rapidly progressive course and early fatality, usually by early childhood.
Question 572: Which protein does the domain of plasminogen resemble?
- A. Fibrinogen (a clotting protein)
- B. LDL receptor (a lipid metabolism protein)
- C. Apolipoprotein (a) (a lipoprotein) (Correct Answer)
- D. Prothrombin (a coagulation protein)
Explanation: ***Apolipoprotein (a) (a lipoprotein)*** - **Plasminogen** and **apolipoprotein (a)** share structural homology, specifically due to the presence of **kringle domains**. - This structural similarity suggests a potential for apolipoprotein (a) to **interfere with plasminogen’s fibrinolytic activity**, contributing to **atherosclerosis**. *Fibrinogen (a clotting protein)* - While plasmin acts on fibrinogen (and its derivative fibrin), its domain structure does not **resemble fibrinogen**. - **Fibrinogen** is a large, multi-domain glycoprotein crucial for **clot formation**, distinct from plasminogen's primarily **kringle-rich structure**. *LDL receptor (a lipid metabolism protein)* - The **LDL receptor** is involved in **cholesterol uptake** by cells and has structural features like ligand-binding repeats and epidermal growth factor (EGF) repeats. - Its domain structure is **not similar to plasminogen**, which is characterized by **kringle domains** and a protease domain. *Prothrombin (a coagulation protein)* - **Prothrombin** is a precursor to thrombin, featuring **gla domains**, kringle-like domains (though structurally distinct from plasminogen's), and a serine protease domain. - While both are involved in coagulation/fibrinolysis, their **overall domain arrangements and specific kringle structures differ** significantly.
Question 573: Which of the following stimulates Acetyl CoA Carboxylase?
- A. Starvation
- B. Glucagon
- C. Citrate (Correct Answer)
- D. None of the options
Explanation: ***Citrate*** - **Citrate** is an allosteric activator of **Acetyl-CoA Carboxylase (ACC)**, indicating abundant energy and precursor availability for fatty acid synthesis. - This activation promotes the conversion of **Acetyl-CoA** to **Malonyl-CoA**, the committed step in **fatty acid synthesis**. *Starvation* - **Starvation** leads to energy deficit, which generally **inhibits** anabolic processes like fatty acid synthesis. - In this state, enzymes involved in anabolic pathways are often downregulated or inhibited to conserve energy. *Glucagon* - **Glucagon** is a hormone that signals low blood glucose and promotes catabolic processes such as **glycogenolysis** and **gluconeogenesis**. - It **inhibits** fatty acid synthesis by phosphorylating and inactivating **Acetyl-CoA Carboxylase**, thus opposing citrate's activating effect. *None of the options* - **Citrate** is a known stimulator of Acetyl CoA Carboxylase. - This option is incorrect because there is a correct answer among the choices.
Question 574: HDL is called good cholesterol because -
- A. Removes cholesterol from peripheral tissues (Correct Answer)
- B. Increases cholesterol delivery to peripheral tissues
- C. Stimulates cholesterol synthesis in the liver
- D. Activates enzymes that break down triglycerides
Explanation: ***Removes cholesterol from peripheral tissues*** - **High-density lipoprotein (HDL)** is known as "good cholesterol" due to its role in **reverse cholesterol transport**, a process where it collects excess cholesterol from peripheral cells and tissues. - This action helps to prevent the accumulation of cholesterol in arteries, thereby reducing the risk of **atherosclerosis** and cardiovascular disease. - HDL then transports this cholesterol to the liver for excretion via bile, completing the protective cycle. *Increases cholesterol delivery to peripheral tissues* - This is actually the opposite of HDL's function and describes the role of **LDL (low-density lipoprotein)**, which is considered "bad cholesterol." - LDL delivers cholesterol to peripheral tissues, and excess LDL can lead to **atherosclerotic plaque formation**. *Stimulates cholesterol synthesis in the liver* - HDL does not directly stimulate cholesterol synthesis in the liver; rather, its role is primarily in **cholesterol efflux** from cells and transport. - The liver's cholesterol synthesis is regulated by various factors, including dietary intake and cellular cholesterol levels via the **SREBP pathway**, but HDL does not upregulate hepatic cholesterol synthesis. *Activates enzymes that break down triglycerides* - While HDL does activate **LCAT (lecithin-cholesterol acyltransferase)** for cholesterol esterification, its primary "good" function is not the breakdown of triglycerides. - **Lipoprotein lipase (LPL)** is the primary enzyme responsible for triglyceride breakdown in lipoproteins like VLDL and chylomicrons.
Community Medicine
2 questionsWhich vaccine is the most widely used globally in childhood vaccination programs, aside from the Oral Polio Vaccine (OPV)?
Which of the following infectious diseases has the highest proportion of asymptomatic chronic carriers?
NEET-PG 2015 - Community Medicine NEET-PG Practice Questions and MCQs
Question 571: Which vaccine is the most widely used globally in childhood vaccination programs, aside from the Oral Polio Vaccine (OPV)?
- A. BCG vaccine
- B. DPT vaccine (Correct Answer)
- C. Influenza vaccine
- D. Pneumococcal vaccine
Explanation: ***DPT vaccine*** - The **DPT (diphtheria, pertussis, and tetanus) vaccine** is the most widely used childhood vaccine globally after OPV, forming the backbone of the **WHO's Expanded Programme on Immunization (EPI)**. - It has **near-universal adoption** across countries worldwide with approximately **86% global coverage** and is administered as a **3-dose primary series** to all children, making it the standard benchmark for measuring immunization program performance. - Its widespread use reflects the global burden of these three bacterial diseases and the vaccine's proven efficacy in preventing severe outcomes and transmission. *BCG vaccine* - The **BCG (Bacillus Calmette-Guérin) vaccine** protects against **tuberculosis** and is widely used, particularly in countries with high TB prevalence. - However, its use is **not universal** – many countries with low TB incidence (such as the USA and several European nations) do not include BCG in routine childhood schedules, limiting its global "universality" compared to DPT. - BCG is typically given as a **single dose at birth**, whereas DPT requires multiple doses throughout infancy. *Influenza vaccine* - The **influenza vaccine** is recommended annually due to antigenic drift of the virus, but its global childhood vaccination coverage is significantly lower compared to standard EPI vaccines like DPT. - It is often prioritized for specific risk groups rather than universal immunization for all children in many parts of the world. *Pneumococcal vaccine* - The **pneumococcal vaccine** targets **Streptococcus pneumoniae**, a cause of pneumonia, meningitis, and other severe diseases. - While increasingly integrated into national immunization schedules, its global adoption (especially as of 2015) was still lower than DPT, with many low- and middle-income countries only recently introducing it.
Question 572: Which of the following infectious diseases has the highest proportion of asymptomatic chronic carriers?
- A. Measles
- B. Rabies
- C. Diphtheria
- D. Hepatitis B (Correct Answer)
Explanation: ***Hepatitis B*** - **Hepatitis B** infection has a significant proportion of **chronic asymptomatic carriers**, particularly when infection occurs perinatally or in early childhood. - In adults, approximately **5% develop chronic infection** after acute exposure, and many of these chronic carriers remain asymptomatic while maintaining infectivity. - Chronic carriers can harbor the virus for years or decades without clinical symptoms, making them an important reservoir for transmission. - This is a major public health concern as asymptomatic carriers can unknowingly transmit the virus. *Measles* - **Measles** is highly contagious and typically presents with **symptomatic disease** in nearly all infected individuals. - Clinical features include characteristic maculopapular rash, cough, coryza, conjunctivitis, and Koplik's spots. - Asymptomatic infection is **extremely rare** with measles virus. *Diphtheria* - While **asymptomatic pharyngeal carriage** of *Corynebacterium diphtheriae* can occur, it is not the predominant pattern. - Clinical diphtheria typically presents with pseudomembrane formation, sore throat, and potential systemic toxin effects. - Carrier rates vary but are not as epidemiologically significant as with Hepatitis B. *Rabies* - **Rabies** is almost **100% symptomatic** once the virus reaches the central nervous system. - There is **no chronic asymptomatic carrier state** in humans. - Once clinical symptoms appear (encephalitis, hydrophobia, paralysis), the disease is virtually always fatal.
Dermatology
1 questionsWhich area is typically not involved in a chickenpox rash?
NEET-PG 2015 - Dermatology NEET-PG Practice Questions and MCQs
Question 571: Which area is typically not involved in a chickenpox rash?
- A. Trunk
- B. Axilla
- C. Back
- D. Palms and soles (Correct Answer)
Explanation: ***Palms and soles*** - The chickenpox rash, caused by the **varicella-zoster virus**, typically spares the palms and soles. - Chickenpox exhibits a characteristic **centripetal distribution** (center-predominant), with lesions most numerous on the trunk and progressively fewer on the extremities. - **Sparing of palms and soles** is a classic differentiating feature from other viral exanthems like hand-foot-and-mouth disease. *Trunk* - The **trunk** is usually the **most heavily involved area** in a chickenpox rash, with lesions often appearing first and being most numerous here. - This is the hallmark of the characteristic **centripetal distribution** of the rash. *Axilla* - The **axilla** is a common site for chickenpox lesions due to its location on the trunk and the presence of **warm, moist skin folds** that can favor lesion development. - The rash tends to be widespread, making secondary sites like the axilla commonly involved. *Back* - The **back** is a major part of the trunk and is therefore extensively involved in a chickenpox rash. - The rash often starts on the trunk and spreads outwards, ensuring significant involvement of the back.
ENT
1 questionsAll of the following are features of Tubotympanic CSOM except which of the following?
NEET-PG 2015 - ENT NEET-PG Practice Questions and MCQs
Question 571: All of the following are features of Tubotympanic CSOM except which of the following?
- A. Profuse discharge
- B. Hearing loss
- C. Extreme pain (Correct Answer)
- D. Facial nerve paralysis
Explanation: ***Extreme pain*** - **Extreme pain** is NOT a characteristic feature of **tubotympanic CSOM**. This type is typically associated with a history of **painless otorrhea**. - Tubotympanic CSOM is considered the "safe" type with inflammation limited to the mucosa without bone erosion. - The presence of severe pain should raise suspicion for complications or the **atticoantral (unsafe) type** of CSOM. *Profuse discharge* - **Profuse, mucoid** or **mucopurulent discharge** is a hallmark feature of tubotympanic CSOM. - This discharge results from chronic inflammation of the **middle ear mucoperiosteum** through a central perforation in the **pars tensa**. - The discharge is typically non-foul smelling (unlike atticoantral CSOM). *Hearing loss* - **Conductive hearing loss** is a universal feature of tubotympanic CSOM. - Results from **tympanic membrane perforation**, middle ear effusion, and potential ossicular discontinuity. - The degree of hearing loss correlates with the size and location of the perforation. *Facial nerve paralysis* - Facial nerve paralysis is **NOT a typical feature** of tubotympanic (safe) CSOM. - This complication is characteristically associated with **atticoantral (unsafe) CSOM** with cholesteatoma causing bone erosion. - While theoretically possible in very advanced neglected tubotympanic disease, it would indicate transformation to unsafe disease or secondary complications. - **Note:** Some sources may list this as a rare complication, but it is not a characteristic feature distinguishing tubotympanic CSOM, making this option potentially ambiguous in an "EXCEPT" question format.
Pharmacology
2 questionsWhich of the following vaccines is not freeze-dried?
What is the Hib conjugate vaccine made of?
NEET-PG 2015 - Pharmacology NEET-PG Practice Questions and MCQs
Question 571: Which of the following vaccines is not freeze-dried?
- A. Measles Vaccine
- B. Diphtheria, Pertussis, and Tetanus (DPT) Vaccine (Correct Answer)
- C. Rubella Vaccine
- D. BCG Vaccine
Explanation: ***Diphtheria, Pertussis, and Tetanus (DPT) Vaccine*** - The DPT vaccine is a **liquid vaccine** that contains inactivated toxins and bacterial components, making it stable in liquid form. - It does not require **freeze-drying** because its components are chemically stable and do not degrade significantly in solution. *Measles Vaccine* - The measles vaccine is a **live attenuated vaccine** that needs to be freeze-dried to maintain the viability and stability of the live virus. - Freeze-drying helps preserve the vaccine's potency by removing water, which prevents degradation during storage and transport. *Rubella Vaccine* - Similar to the measles vaccine, the rubella vaccine is a **live attenuated vaccine** and is therefore provided in a freeze-dried form. - This process ensures the long-term stability and efficacy of the viral components, which would otherwise degrade in a liquid state. *BCG Vaccine* - The BCG (Bacillus Calmette-Guérin) vaccine is a **live attenuated bacterial vaccine** used against tuberculosis, and it is also manufactured as a freeze-dried product. - Freeze-drying is essential for maintaining the viability of the live attenuated *Mycobacterium bovis* strain.
Question 572: What is the Hib conjugate vaccine made of?
- A. Capsular polysaccharide
- B. Purified protein with carrier
- C. Cell wall polysaccharide
- D. Capsular polysaccharide with carrier (Correct Answer)
Explanation: ***Capsular polysaccharide with carrier*** - The Hib conjugate vaccine uses a **polysaccharide capsule** from *Haemophilus influenzae* type b (Hib) covalently linked to a **protein carrier** [1]. - This conjugation allows activated B cells to present the polysaccharide to T helper cells, inducing a strong **T-cell dependent immune response** and **immunological memory**, especially in infants [1]. *Capsular polysaccharide* - A vaccine made only of **capsular polysaccharide** would be a **polysaccharide vaccine**, which induces a **T-cell independent immune response**. - This type of vaccine is **poorly immunogenic in infants** and does not generate long-lasting memory. *Purified protein with carrier* - This describes components of some **protein subunit vaccines**, but not specifically the Hib vaccine, which targets the polysaccharide capsule. - While it employs a carrier protein, the primary antigen is the **polysaccharide**, not a purified bacterial protein. *Cell wall polysaccharide* - The Hib vaccine specifically targets the **capsular polysaccharide**, which is distinct from the general cell wall polysaccharides found in the bacterial outer membrane. - The **capsule** is the primary virulence factor and target for protective immunity in Hib.