NEET-PG 2013 Practice Questions

Q: All pass through jugular foramen except

Mandibular nerve. ***Mandibular nerve*** - The **mandibular nerve** (CN V3) exits the skull through the **foramen ovale**, not the jugular foramen. - It is a branch of the **trigeminal nerve** and is responsible for motor innervation to muscles of mastication and sensory innervation to the lower face and mouth. *Glossopharyngeal nerve* - The **glossopharyngeal nerve** (CN IX) is one of the three cranial nerves that exit through the **jugular foramen**. - It provides motor, sensory, and parasympathetic innervation including taste from posterior third of tongue and motor to stylopharyngeus muscle. *Vagus nerve* - The **vagus nerve** (CN X) is one of the major cranial nerves that exits the skull through the **jugular foramen**. - It provides extensive motor, sensory, and parasympathetic innervation to the head, neck, thorax, and abdomen. *Internal jugular vein* - The **internal jugular vein** is formed at the jugular foramen by the continuation of the **sigmoid sinus**, and it exits the skull through this foramen. - It is one of the primary venous drainage pathways for the brain.

Q: Which metabolic pathway provides instant energy to muscles?

Embden-Meyerhof pathway. ***Embden-Meyerhof pathway*** - This pathway, also known as **glycolysis**, rapidly breaks down glucose into pyruvate to produce **ATP without oxygen**, providing instant energy to muscles during high-intensity activity. - Generates a net of **two ATP molecules** per glucose molecule, which is crucial for quick bursts of energy. *HMP shunt* - The **hexose monophosphate shunt** primarily produces **NADPH** for reductive biosynthesis and **ribose-5-phosphate** for nucleotide synthesis, not immediate large-scale ATP for muscle contraction. - Plays a role in protecting cells from **oxidative stress** and synthesizing precursors for DNA and RNA. *Cori cycle* - The **Cori cycle** involves the recycling of **lactate** produced in muscles back to glucose in the liver, which is a slower process for maintaining glucose homeostasis rather than providing instant muscle energy. - It helps prevent **lactic acidosis** during strenuous activity but is not a primary pathway for rapid ATP generation. *TCA cycle* - The **TCA cycle (Krebs cycle)** is part of **aerobic respiration** and produces a significant amount of ATP, but it is a slower, more sustained energy production pathway that requires oxygen. - Primarily active during **lower-intensity**, longer-duration activities when oxygen supply is adequate.

Q: Rate limiting step in pyrimidine synthesis?

Carbamoyl phosphate synthase-II. ***Carbamoyl phosphate synthetase II (CPS-II)*** - **CPS-II** is the **committed and rate-limiting enzyme** in **de novo pyrimidine synthesis** in **mammals (including humans)** - It catalyzes the formation of **carbamoyl phosphate** from glutamine, CO₂, and 2 ATP in the **cytoplasm** - This is the **first committed step** and the main **regulatory checkpoint**, inhibited by UTP (feedback inhibition) and activated by PRPP and ATP - CPS-II is part of the **CAD complex** (carbamoyl phosphate synthetase, aspartate transcarbamoylase, dihydroorotase) in mammals *Aspartate transcarbamoylase (ATCase)* - ATCase catalyzes the **second step**: condensation of carbamoyl phosphate with aspartate to form carbamoyl aspartate - While ATCase is the **rate-limiting step in bacteria** (E. coli), in **mammals** it is part of the CAD complex and **not the primary regulatory step** - This option is incorrect for human/mammalian biochemistry tested in NEET PG *Dihydro-orotase* - The **third enzyme** in the pathway, converting carbamoyl aspartate to dihydroorotate - Part of the CAD complex in mammals but **not the rate-limiting step** *Dihydroorotate dehydrogenase* - Catalyzes the **fourth step**: oxidation of dihydroorotate to orotate - Located on the **outer surface of the inner mitochondrial membrane** (only mitochondrial enzyme in the pathway) - Important enzyme but **not rate-limiting**

Q: In which condition are Pseudo-Pelger-Huët cells typically seen?

Myelodysplastic syndrome. ***Mylodysplastic syndrome*** - Pseudo-Pelger-Huet cells are characteristic and often observed in myelodysplastic syndromes, indicating an ineffective hematopoiesis [1]. - These cells appear as **hyposegmented neutrophils** and are associated with dysplastic changes in the bone marrow [1]. *Hairy cell leukemia* - Typically presents with **hairy cells** in peripheral blood and often involves splenomegaly; pseudo-Pelger-Huet cells are not usual in this condition. - Associated with **PANCYTOPENIA** and reticulin fibrosis, differing from myelodysplastic syndrome. *Hodgkin's lymphoma* - Characterized by the presence of **Reed-Sternberg cells** and typically involves lymphadenopathy. - Peripheral blood findings generally do not include pseudo-Pelger-Huet cells; the focus is on lymphatic tissue. *Multiple myeloma* - Commonly presents with **plasma cells** and related symptoms like bone pain and renal failure, not associated with pseudo-Pelger-Huet cells. - It primarily causes an increase in monoclonal proteins rather than dysplastic changes seen in myelodysplastic syndrome. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 613-614.

Q: Thalassemia gives protection against ?

Protection against malaria. Protection against malaria - Individuals with thalassemia, particularly thalassemia trait, have some degree of protection against severe forms of malaria, specifically Plasmodium falciparum [1]. - The altered red blood cell structure and reduced hemoglobin content in thalassemia make the red blood cells less hospitable for the parasites, hindering their replication and survival [1]. Protection against filaria - Filaria is caused by parasitic worms (nematodes) transmitted by mosquitoes, leading to lymphatic filariasis (elephantiasis) or onchocerciasis (river blindness). - Thalassemia's primary impact is on red blood cell health and oxygen transport, offering no known protective effect against nematode infections or their associated pathology. Protection against kala-azar - Kala-azar (visceral leishmaniasis) is caused by Leishmania parasites transmitted by sandflies, primarily affecting the reticuloendothelial system (spleen, liver, bone marrow). - There is no established scientific evidence indicating that thalassemia provides protection against Leishmania infections or their clinical manifestations. Protection against leptospirosis - Leptospirosis is a bacterial infection caused by Leptospira bacteria, typically acquired through contact with contaminated water or animal urine. - Thalassemia is a genetic blood disorder; its physiological effects are unrelated to the mechanisms of infection or immunity against bacterial pathogens like Leptospira.

Q: In the context of pharmacology, which plasma protein do acidic drugs primarily bind to?

Albumin. ***Albumin*** - **Albumin** is the most abundant plasma protein and has multiple binding sites for a wide range of drugs, particularly **acidic drugs**. - Its high concentration and diverse binding capabilities make it the primary transporter for many **lipophilic** and **anionic drugs**. *Globulin* - **Globulins** are a diverse group of proteins, some of which bind to drugs, but they primarily transport **hormones**, **metals**, and **vitamins**, not acidic drugs. - They are less significant for binding acidic drugs compared to albumin. *α1-acid glycoprotein* - **α1-acid glycoprotein** primarily binds to **basic drugs** due to its numerous acidic residues. - While it plays a crucial role in binding basic compounds, it has limited affinity for acidic drugs. *None of the options* - This option is incorrect because **albumin** is a well-established and significant plasma protein for binding acidic drugs. - Specific plasma proteins are known to bind different types of drugs, and for acidic drugs, albumin is the primary binder.

Q: Which drug has the highest plasma protein binding?

Warfarin. ***Warfarin*** - **Warfarin** exhibits very **high plasma protein binding**, typically greater than 99%, primarily to albumin. - This high binding capacity means that only a small fraction of the drug is free and pharmacologically active. - Due to high protein binding, warfarin is susceptible to drug interactions when displaced from albumin. *Verapamil* - **Verapamil** has a relatively high plasma protein binding, around 90%, but it is not as high as warfarin. - Its binding is predominantly to **albumin** and alpha-1-acid glycoprotein. *Aspirin* - **Aspirin** (acetylsalicylic acid) has moderate plasma protein binding, usually between 50-90%, depending on the dosage. - It binds to **albumin** and can displace other protein-bound drugs. *GTN* - **Glyceryl trinitrate (GTN)** has moderate plasma protein binding, approximately 60%. - Its rapid onset and short duration of action are primarily due to its extensive first-pass metabolism and quick redistribution, rather than protein binding characteristics.

Q: Which of the following is classified as an antispasmodic agent?

Dicyclomine. ***Dicyclomine*** - **Dicyclomine** is an **anticholinergic** medication that works by blocking muscarinic receptors, thereby reducing smooth muscle spasm in the gastrointestinal tract. - It is commonly used to treat symptoms of **irritable bowel syndrome (IBS)**, such as abdominal pain and cramping. *Physostigmine* - **Physostigmine** is a **cholinesterase inhibitor** that increases the concentration of acetylcholine at the synaptic cleft. - It is used to treat **anticholinergic poisoning** by reversing the effects of anticholinergic drugs, rather than acting as an antispasmodic itself. *Tropicamide* - **Tropicamide** is an **anticholinergic** agent primarily used as a **mydriatic** (pupil dilator) and **cycloplegic** (paralyzes the ciliary muscle) for ophthalmic examinations. - Its action is localized to the eye and it does not have significant systemic antispasmodic effects. *None of the options* - This option is incorrect because one of the listed medications is indeed classified as an antispasmodic agent. - When "None of the options" appears as a choice, it should only be selected if all other options are clearly incorrect.

Q: Which of the following statements is true regarding post-ganglionic parasympathetic fibers?

They release acetylcholine at the target organs.. ***They release acetylcholine at the target organs.*** - Post-ganglionic parasympathetic fibers are **cholinergic**, meaning they release the neurotransmitter **acetylcholine** at their effector organs. - This action mediates the characteristic "rest and digest" responses of the parasympathetic nervous system. *They originate from the spinal cord.* - **Pre-ganglionic parasympathetic fibers** originate from the **brainstem** (cranial nerves III, VII, IX, X) and the **sacral spinal cord** (S2-S4). - Post-ganglionic fibers originate in ganglia located near or within their target organs, not the spinal cord directly. *They are part of the sympathetic nervous system.* - Post-ganglionic parasympathetic fibers are a component of the **parasympathetic nervous system**, not the sympathetic nervous system. - The sympathetic and parasympathetic systems are distinct divisions of the autonomic nervous system with generally opposing functions. *They are responsible for 'fight or flight' responses.* - The **'fight or flight' response** is characteristic of the **sympathetic nervous system**, which prepares the body for stressful situations. - The parasympathetic nervous system is responsible for **'rest and digest' functions**, promoting energy conservation and maintenance activities.

Question 1

All pass through jugular foramen except

Accepted Answer

Mandibular nerve

Answer

Vagus nerve

Answer

Internal jugular vein

Answer

Glossopharyngeal nerve

Question 2

Which of the following statements about G protein-coupled receptors (GPCRs) is true?

Accepted Answer

G proteins can act as either inhibitory or excitatory based on the type of alpha subunit.

Answer

The three subunits alpha, beta, and gamma must remain together as a complex for G protein to function.

Answer

G proteins bind directly to hormones to become activated.

Answer

In the resting state, G proteins are bound to GTP.

Question 3

Which metabolic pathway provides instant energy to muscles?

Accepted Answer

Embden-Meyerhof pathway

Answer

HMP shunt

Answer

Cori cycle

Answer

TCA cycle

Question 4

Rate limiting step in pyrimidine synthesis?

Accepted Answer

Carbamoyl phosphate synthase-II

Answer

Aspartate transcarbamoylase (ATCase)

Answer

Dihydroorotate dehydrogenase

Answer

Dihydro-orotase

Question 5

In which condition are Pseudo-Pelger-Huët cells typically seen?

Accepted Answer

Myelodysplastic syndrome

Answer

Hairy cell leukemia

Answer

Multiple myeloma

Answer

Hodgkin's lymphoma

Question 6

Thalassemia gives protection against ?

Accepted Answer

Protection against malaria

Answer

Protection against filaria

Answer

Protection against kala-azar

Answer

Protection against leptospirosis

Question 7

In the context of pharmacology, which plasma protein do acidic drugs primarily bind to?

Accepted Answer

Albumin

Answer

Globulin

Answer

α1-acid glycoprotein

Answer

None of the options

Question 8

Which drug has the highest plasma protein binding?

Accepted Answer

Warfarin

Answer

Verapamil

Answer

Aspirin

Answer

GTN

Question 9

Which of the following is classified as an antispasmodic agent?

Accepted Answer

Dicyclomine

Answer

Physostigmine

Answer

Tropicamide

Answer

None of the options

Question 10

Which of the following statements is true regarding post-ganglionic parasympathetic fibers?

Accepted Answer

They release acetylcholine at the target organs.

Answer

They originate from the spinal cord.

Answer

They are part of the sympathetic nervous system.

Answer

They are responsible for 'fight or flight' responses.

NEET-PG 2013

Anatomy

Biochemistry

Pathology

Pharmacology

Physiology