NEET-PG 2019 Practice Questions

Q: Hyperammonaemia inhibits the TCA cycle by depleting which of the following?

α-ketoglutarate. ***a keto glutarate*** - **Hyperammonemia** leads to the depletion of **α-ketoglutarate** through its amination to form **glutamate** by glutamate dehydrogenase and subsequently glutamine by glutamine synthetase. - The removal of **α-ketoglutarate** from the TCA cycle impairs its ability to produce energy and essential intermediates, contributing to neurological dysfunction in hyperammonemia. *succinate* - **Succinate** is an intermediate in the TCA cycle, but its depletion is not the primary mechanism by which hyperammonemia inhibits the cycle. - The direct consumption of **α-ketoglutarate** for ammonia detoxification is the more direct and significant impact. *malate* - **Malate** is another intermediate in the TCA cycle but is downstream from **α-ketoglutarate**. - Its depletion is a consequence of overall TCA cycle inhibition, not the initial cause mediated by hyperammonemia. *fumarate* - **Fumarate** is also a TCA cycle intermediate and is produced after succinate. - Its levels would be affected by the overall inhibition of the cycle, but it is not the direct target or substrate for ammonia detoxification that depletes the cycle.

Q: Which syndrome is associated with posterior inferior cerebellar artery thrombosis?

Wallenberg syndrome. No specific references from the provided list reached the relevance threshold (score >= 7) to be cited in the explanation. The original text remains unchanged. ***Wallenberg syndrome*** - Also known as **lateral medullary syndrome**, it is caused by **thrombosis of the posterior inferior cerebellar artery (PICA)** or its branches. - Symptoms include ipsilateral **ataxia**, **vertigo**, **nystagmus**, dysphagia, and contralateral loss of pain and temperature sensation. *Medial medullary syndrome* - This syndrome results from occlusion of the **anterior spinal artery** and paramedian branches of the **vertebral artery**. - Clinical features include contralateral **hemiparesis**, ipsilateral **tongue deviation**, and loss of position and vibration sensation. *Inferior alternating syndrome* - This is another name for **medial medullary syndrome**, caused by a lesion in the **medulla oblongata**. - It is characterized by ipsilateral cranial nerve signs and contralateral long tract signs, differentiating it from Wallenberg syndrome. *Dejerine syndrome* - Also known as **medial medullary syndrome**, it is linked to occlusion of the **anterior spinal artery**. - Symptoms primarily involve the **pyramidal tract**, **medial lemniscus**, and **hypoglossal nerve**.

Q: A 36-year-old male patient complaining of cough, cold, fever, and rusty sputum, with a history of travel to China and consumption of crab. Name the infection.

Paragonimus westermani. ***Paragonimus westermani*** - This patient's symptoms of **cough**, **fever**, and **rusty sputum**, combined with a history of **travel to China** and consumption of **crab**, are highly suggestive of **paragonimiasis**. - *Paragonimus westermani* is a **lung fluke** endemic to East Asia, and its larvae are acquired by ingesting undercooked **crabs** or **crayfish**. *Fasciola hepatica* - *Fasciola hepatica* causes **fascioliasis**, primarily affecting the **liver** and **biliary ducts**, leading to symptoms like **fever**, **abdominal pain**, and **hepatomegaly**. - It is acquired by consuming **contaminated watercress** or other aquatic plants, not crabs. *Fasciolopsis buski* - *Fasciolopsis buski* causes **fasciolopsiasis**, an **intestinal fluke infection** presenting with **abdominal pain**, **diarrhea**, and **malabsorption**. - It is transmitted through ingestion of **contaminated aquatic plants**, and does not typically cause respiratory symptoms or "rusty sputum." *Entamoeba histolytica* - *Entamoeba histolytica* is a **protozoan** that causes **amoebiasis**, primarily presenting as **dysentery** or **amoebic liver abscess**. - While it can manifest as fever and liver involvement, it does not cause respiratory symptoms like "rusty sputum" and is not acquired from crabs.

Q: Rubella virus belongs to which family?

Togavirus. ***Togavirus*** - The **Rubella virus** is categorized under the family **Togaviridae**, specifically within the genus *Rubivirus*. - This classification is based on its genetic structure, being an **enveloped, positive-sense, single-stranded RNA virus**. *Rheovirus* - **Reoviruses** are characterized by a **double-stranded segmented RNA genome** and are typically non-enveloped. - This contrasts with Rubella's single-stranded, non-segmented RNA and enveloped structure. *Picornavirus* - **Picornaviruses** are a family of **non-enveloped, positive-sense, single-stranded RNA viruses** that are structurally different from Rubella. - Examples include species like **poliovirus** and **rhinovirus**, which do not share the distinct biological properties of Rubella. *Orthomyxovirus* - **Orthomyxoviruses** are a family of **enveloped, negative-sense, segmented RNA viruses**, which includes influenza viruses. - Their genomic organization and replication strategy are fundamentally different from those of the Rubella virus.

Q: Carbapenem which has a tendency to cause maximum seizures?

Imipenem. ***Imipenem*** - **Imipenem** is associated with the highest risk of **seizures** among the carbapenems, particularly in patients with **renal impairment**, pre-existing **CNS disorders**, or high doses. - Its high affinity for **GABA-A receptors** in the central nervous system is thought to contribute to its proconvulsant effects. *Ertapenem* - While all carbapenems carry some risk of seizures, **ertapenem** has a **lower incidence** compared to imipenem. - It is often favored in patients without CNS infections or severe renal dysfunction due to its once-daily dosing. *Doripenem* - **Doripenem** also has a relatively **low risk of seizures** compared to imipenem. - It is generally well-tolerated, with side effects similar to other carbapenems but at a reduced frequency for CNS events. *Meropenem* - **Meropenem** is known to have a **lower seizure potential** than imipenem, making it a preferred choice for patients with a history of seizures or those with CNS infections. - Its **reduced affinity** for GABA-A receptors contributes to its better CNS tolerability.

Q: Which of the following drugs is used in SIADH?

Tolvaptan. ***Tolvaptan*** - **Tolvaptan** is a **vasopressin receptor antagonist** that blocks the action of **antidiuretic hormone (ADH)** at the **V2 receptors** in the kidneys [1]. - This action promotes **water excretion (aquaresis)** without significantly affecting electrolyte balance, thereby increasing serum sodium levels in patients with **SIADH** [1]. *Desmopressin* - **Desmopressin** is a synthetic analog of **ADH** that primarily acts on **V2 receptors**, promoting water reabsorption [3], [4]. - It is used in conditions like **diabetes insipidus** [3], [4] or **hemophilia** [2] to increase ADH activity or clotting factors, which is contrary to the goal in SIADH. *Von Willebrand factor* - **Von Willebrand factor** is a **glycoprotein** involved in **hemostasis**, promoting platelet adhesion and carrying **factor VIII**. - It plays no role in the direct management of **SIADH** or fluid balance disorders. *Terlipressin* - **Terlipressin** is an analog of **vasopressin** that primarily acts on **V1 receptors**, causing vasoconstriction [5]. - It is used in conditions like **hepatorenal syndrome** or **esophageal variceal bleeding**, not for treating **SIADH**.

Q: What is the drug of choice (DOC) for a scorpion sting bite?

Prazosin. ***Prazosin*** - **Prazosin** is an **alpha-1 adrenergic antagonist** that effectively counteracts the symptoms of scorpion envenomation, particularly **autonomic hyperactivity** like hypertension and tachycardia. - It works by blocking the effects of norepinephrine released by the scorpion venom, helping to stabilize vital signs and reduce cardiovascular complications. *EDTA* - **EDTA (ethylenediaminetetraacetic acid)** is a **chelating agent** primarily used to treat **heavy metal poisoning**, such as lead or mercury. - It binds to metal ions, forming a stable complex that can then be excreted from the body; it has no role in scorpion envenomation. *Neostigmine* - **Neostigmine** is an **acetylcholinesterase inhibitor** used to treat conditions like myasthenia gravis or to reverse the effects of neuromuscular blocking agents. - It increases acetylcholine levels at the neuromuscular junction; it is not indicated for the management of scorpion stings. *N-acetylcysteine* - **N-acetylcysteine (NAC)** is primarily used as an **antidote for acetaminophen overdose** and as a mucolytic agent in respiratory conditions. - It replenishes glutathione stores, helping to detoxify harmful metabolites; it has no direct role in treating scorpion venom effects.

Q: What is the effect of the Bainbridge reflex?

Increased heart rate. ***Increased heart rate*** - The **Bainbridge reflex** produces an increase in heart rate (tachycardia). - This reflex is triggered by an increase in **venous return** and **atrial distension**, which stimulates stretch receptors in the atria, leading to increased heart rate. - The reflex helps prevent venous pooling and maintains efficient cardiac function. *Bradycardia* - **Bradycardia** (slow heart rate) is the opposite effect of the Bainbridge reflex. - Other reflexes like the **baroreceptor reflex** can cause bradycardia when arterial pressure increases. *Increased cardiac output* - While increased heart rate can contribute to **increased cardiac output**, this is a secondary consequence, not the primary effect of the reflex. - Cardiac output = Heart rate × Stroke volume, so the direct effect is on heart rate. *Decreased venous return* - The Bainbridge reflex does not cause decreased venous return. - Instead, the reflex is **triggered by increased** venous return and responds by increasing heart rate to accommodate the increased blood flow.

Q: With increase in age, which of the following statements about lung function is true?

Pulmonary compliance increases. ***Pulmonary compliance increases*** - With **increasing age**, there is a loss of **elastic recoil** in the lungs due to changes in elastin and collagen fibers, leading to an increase in **pulmonary compliance**. - This increased compliance means the lungs become less stiff and easier to inflate, but also less able to recoil and expel air effectively. - The **net effect** of aging is increased compliance, as the loss of elastic fibers is the predominant change in normal aging. *Residual volume decreases* - **Residual volume (RV)** actually **increases** with age. This is because the loss of elastic recoil makes it harder to fully exhale, causing more air to remain in the lungs after a maximal exhalation. - An increased residual volume contributes to an overall rise in **functional residual capacity** and total lung capacity in older adults. *Mucociliary clearance increases* - **Mucociliary clearance** generally **decreases** with age. This is due to a reduction in the number and function of cilia, as well as changes in mucus quality. - Impaired mucociliary clearance makes older individuals more susceptible to respiratory infections and difficulties in clearing secretions. *Fibrosis of the interstitium decreases* - The **fibrosis of the interstitium** can **increase** with age in some individuals. However, in normal aging (without pathological conditions), the predominant change is loss of elastic recoil rather than significant fibrotic changes. - When present, increased interstitial fibrosis would make the lungs stiffer, but this is not the primary age-related change in healthy individuals.

Q: Tubuloglomerular feedback control is useful for which one of the following?

GFR. ***GFR*** - **Tubuloglomerular feedback (TGF)** is a critical autoregulatory mechanism that maintains a relatively constant **glomerular filtration rate (GFR)** despite fluctuations in arterial blood pressure. - The **macula densa** cells at the end of the thick ascending limb of the loop of Henle sense the **volume** and **sodium chloride concentration** of the tubular fluid and release paracrine factors to adjust afferent arteriolar resistance. *Plasma sodium* - While TGF senses the **sodium chloride concentration** in the filtrate, its primary role is to regulate GFR, not directly control systemic plasma sodium levels. - Plasma sodium is primarily regulated by hormones like **ADH** and **aldosterone**, which influence water reabsorption and sodium excretion. *Plasma volume* - **Plasma volume** is regulated predominantly by hormonal mechanisms (e.g., **renin-angiotensin-aldosterone system**, **ADH**, **ANP**) and control over overall sodium and water balance, rather than by the acute, intrinsic GFR regulation of TGF. - Changes in plasma volume can indirectly affect GFR, but TGF is not the direct control mechanism for plasma volume itself. *Determining tubular secretion* - **Tubular secretion** is the process by which solutes are actively transported from the peritubular capillaries into the tubular lumen. - TGF influences **glomerular filtration**, not directly the rates of tubular secretion, which are regulated by specific transport proteins and physiological needs.

Question 1

Hyperammonaemia inhibits the TCA cycle by depleting which of the following?

Accepted Answer

α-ketoglutarate

Answer

succinate

Answer

malate

Answer

fumarate

Question 2

Which syndrome is associated with posterior inferior cerebellar artery thrombosis?

Accepted Answer

Wallenberg syndrome

Answer

Medial medullary syndrome

Answer

Inferior alternating syndrome

Answer

Dejerine syndrome

Question 3

A 36-year-old male patient complaining of cough, cold, fever, and rusty sputum, with a history of travel to China and consumption of crab. Name the infection.

Accepted Answer

Paragonimus westermani

Answer

Fasciola hepatica

Answer

Fasciolopsis buski

Answer

Entamoeba histolytica

Question 4

Rubella virus belongs to which family?

Accepted Answer

Togavirus

Answer

Orthomyxovirus

Answer

Rheovirus

Answer

Picornavirus

Question 5

Carbapenem which has a tendency to cause maximum seizures?

Accepted Answer

Imipenem

Answer

Ertapenem

Answer

Doripenem

Answer

Meropenem

Question 6

Which of the following drugs is used in SIADH?

Accepted Answer

Tolvaptan

Answer

Desmopressin

Answer

Terlipressin

Answer

Von Willebrand factor

Question 7

What is the drug of choice (DOC) for a scorpion sting bite?

Accepted Answer

Prazosin

Answer

EDTA

Answer

Neostigmine

Answer

N-acetylcysteine

Question 8

What is the effect of the Bainbridge reflex?

Accepted Answer

Increased heart rate

Answer

Bradycardia

Answer

Increased cardiac output

Answer

Decreased venous return

Question 9

With increase in age, which of the following statements about lung function is true?

Accepted Answer

Pulmonary compliance increases

Answer

Fibrosis of the interstitium decreases

Answer

Residual volume decreases

Answer

Mucociliary clearance increases

Question 10

Tubuloglomerular feedback control is useful for which one of the following?

Accepted Answer

GFR

Answer

Plasma sodium

Answer

Plasma volume

Answer

Determining tubular secretion

NEET-PG 2019

Biochemistry

Internal Medicine

Microbiology

Pharmacology

Physiology