INI-CET 2024 Practice Questions

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: Best blood product to be given in a patient of multiple clotting factor deficiency with active bleeding:

Fresh frozen plasma. ***Fresh frozen plasma*** - **Fresh frozen plasma (FFP)** contains all coagulation factors, including labile factors V and VIII, making it the best choice for patients with multiple clotting factor deficiencies and active bleeding. - It rapidly replenishes clotting factors, which is critical in scenarios of **acute hemorrhage** due to global coagulopathy. *Whole blood* - **Whole blood** contains red blood cells, plasma, and platelets, but its clotting factor concentration is lower than FFP and deteriorates over storage. - It is preferred for massive hemorrhage with significant blood volume loss, but less effective for isolated clotting factor deficiencies without substantial volume depletion. *Packed RBCs* - **Packed red blood cells (PRBCs)** are primarily used to increase oxygen-carrying capacity by raising hemoglobin levels in anemic patients. - They lack significant amounts of clotting factors and are therefore not effective in treating active bleeding due to coagulation factor deficiencies. *Cryoprecipitate* - **Cryoprecipitate** contains specific clotting factors, namely factor VIII, von Willebrand factor, fibrinogen, and factor XIII. - While useful for deficiencies in these specific factors (e.g., hemophilia A, DIC with low fibrinogen), it does not provide a broad spectrum of all clotting factors needed for general multiple factor deficiencies.

Q: Allergic salute is seen in -

Allergic rhinitis. ***Allergic rhinitis*** - The **allergic salute** is a characteristic physical finding in allergic rhinitis [1], where individuals repeatedly push their nose upward with their hand to relieve nasal itching and clear obstruction. - This repetitive gesture can lead to a visible transverse crease on the dorsum of the nose, known as the **nasal crease**. *Nasal Myiasis* - **Nasal myiasis** is an infestation of the nasal cavity by fly larvae, causing symptoms like nasal discharge, epistaxis, and local pain. - It does not involve nasal itching that would provoke the "allergic salute" action. *Chronic sinusitis* - **Chronic sinusitis** is a prolonged inflammation of the sinuses, causing facial pain/pressure, nasal obstruction, and discharge. - While it can cause nasal obstruction, it typically doesn't present with the intense nasal itching that would lead to the "allergic salute." *Chronic conjunctivitis* - **Chronic conjunctivitis** is an inflammation of the conjunctiva, primarily affecting the eyes with symptoms like redness, itching, and discharge. - It does not directly affect the nasal passages or provoke nasal symptoms like itching that would result in an allergic salute.

Q: A-wave in Electroretinogram corresponds to the activity of

Rods and cones. ***Rods and cones*** - The **'a' wave** of the Electroretinogram (ERG) represents the **initial negative deflection**, primarily generated by the activity of the **photoreceptors** (rods and cones) in response to light stimulation. - This wave reflects the **hyperpolarization** of the photoreceptor cells as they absorb light and initiate the visual transduction cascade. *Pigment epithelium* - The **retinal pigment epithelium (RPE)** plays a crucial role in supporting photoreceptor function and has a slower, sustained electrical response, which contributes more to the **c-wave** of the ERG. - While the RPE is vital for retinal function, its primary electrical contribution is not represented by the initial negative a-wave. *Nerve fibre layer* - The **nerve fiber layer** consists of the axons of ganglion cells and does not directly contribute to the primary a-wave or b-wave of the ERG as it is involved in transmitting signals to the brain. - Damage to this layer may affect overall visual function but is not the source of the initial photoreceptor-driven electrical response. *Ganglion cell layer* - The **ganglion cell layer** is responsible for sending visual information to the brain, and its activity is typically reflected in later, more complex components of the ERG or in other electrophysiological tests like pattern ERG. - The initial photoreceptor response (a-wave) occurs upstream of the ganglion cell activity.

Q: The site of action of the loop diuretic furosemide is:

Thick ascending limb of loop of Henle. ***Thick ascending limb of loop of Henle*** - Furosemide, a **loop diuretic**, acts by inhibiting the **Na+-K+-2Cl- cotransporter (NKCC2)** in the luminal membrane of the epithelial cells in the thick ascending limb. - This inhibition prevents the reabsorption of these ions, leading to increased excretion of **sodium**, **potassium**, **chloride**, and water. *Distal convoluted tubule* - This is the primary site of action for **thiazide diuretics**, which inhibit the **Na+-Cl- cotransporter**. - While some water reabsorption occurs here, it is not the main target for loop diuretics like furosemide. *Descending limb of loop of Henle* - This segment is primarily permeable to **water** due to aquaporins but impermeable to solutes, allowing for passive water reabsorption. - No significant transport mechanisms are directly targeted by furosemide here. *Proximal convoluted tubule* - The proximal tubule is where the majority of filtered **sodium**, **water**, and other solutes are reabsorbed. - **Carbonic anhydrase inhibitors** (e.g., acetazolamide) primarily act here.

Q: Which of the following is not a paraphilia?

Adultery. ***Adultery*** - **Adultery** refers to consensual sexual activity between a married person and someone who is not their spouse. - While it may involve **moral** or **social transgression**, it does not inherently involve **unusual sexual fantasies** or **non-consenting partners** that define paraphilias. *Necrophilia* - **Necrophilia** is a paraphilia defined by sexual attraction to or sexual acts with **corpses**. - It involves a **deviation from typical sexual arousal** patterns towards a non-living object. *Fetishism* - **Fetishism** is a paraphilia characterized by recurrent, intense **sexual arousal from inanimate objects** (e.g., shoes, clothing) or specific non-genital body parts. - The object or body part is essential for **sexual gratification**. *Paedophilia* - **Paedophilia** is a paraphilia involving recurrent, intense sexual attraction to **prepubescent children**. - This paraphilia is characterized by the **sexual targeting of children**, which falls outside of typical sexual behaviors and is illegal.

Q: Which sign on chest X-ray indicates tension pneumothorax?

Mediastinal shift. ***Mediastinal shift*** - **Mediastinal shift** away from the affected side is the **most specific and critical radiographic sign** of tension pneumothorax on chest X-ray. - The progressive air accumulation under positive pressure pushes the **mediastinum** (heart, great vessels, trachea) toward the contralateral side, causing life-threatening **cardiorespiratory compromise** by impeding venous return and cardiac output. - This finding distinguishes tension pneumothorax from simple pneumothorax and mandates **immediate needle decompression**. *Flattened diaphragm* - A **flattened or depressed hemidiaphragm** can occur in tension pneumothorax due to increased intrapleural pressure pushing the diaphragm downward. - However, this sign is **non-specific** as it also occurs in simple pneumothorax, hyperinflation, COPD, and other conditions. - While supportive, it does not definitively indicate the high-pressure tension state. *Deep sulcus sign* - The **deep sulcus sign** (abnormally deep and lucent costophrenic angle) is seen on **supine chest X-rays** when air accumulates anteriorly and inferiorly in the pleural space. - This indicates pneumothorax but is **not specific for tension pneumothorax** and can be seen in simple pneumothorax. - It is position-dependent and does not indicate mediastinal compression. *All of the options* - While flattened diaphragm and deep sulcus sign **may be present** in tension pneumothorax, only **mediastinal shift** is the **definitive radiographic indicator** that distinguishes tension from simple pneumothorax. - Mediastinal shift is the key finding that reflects the pathophysiological pressure differential causing cardiovascular compromise.

Q: X-ray chest in a neonate may show 'ground glass' haziness in all the following conditions EXCEPT:

Left-to-right shunt. ***Left-to-right shunt*** - A **left-to-right shunt** in a neonate typically causes an increase in pulmonary blood flow, leading to vascular congestion and possibly **cardiomegaly**, not ground-glass haziness. - While prolonged significant shunting can lead to pulmonary edema, classic "ground glass" haziness is more characteristic of diffuse lung pathology. *Obstructed TAPVC* - **Obstructed total anomalous pulmonary venous connection (TAPVC)** leads to severe pulmonary venous congestion, resulting in **pulmonary edema** and a classic **ground-glass appearance** on chest X-ray. - This condition is a surgical emergency due to severe respiratory distress and lung opacification. *Staphylococcal pneumonia* - **Staphylococcal pneumonia** in neonates can cause extensive **pulmonary inflammation** and **exudate formation**, leading to a diffuse alveolar filling pattern that appears as ground-glass opacities. - This is a severe form of pneumonia that can rapidly progress. *Hyaline membrane disease* - **Hyaline membrane disease (respiratory distress syndrome)** is characterized by surfactant deficiency, leading to diffuse **atelectasis** and **pulmonary edema**, which manifests as a **ground-glass appearance** on chest X-ray. - This condition commonly affects premature infants and is associated with air bronchograms.

Q: Which of the following contrast agents is PREFERRED in a patient with renal dysfunction for the prevention of contrast-induced nephropathy?

Iso-osmolar contrast. ***Iso-osmolar contrast*** - **Iso-osmolar contrast agents** (e.g., iodixanol) have an osmolality of ~290 mOsm/kg, which is identical to that of plasma. - **This is the PREFERRED choice** in patients with renal dysfunction as multiple studies demonstrate the lowest risk of contrast-induced nephropathy (CIN). - The iso-osmolar formulation minimizes osmotic stress on renal tubules and reduces the risk of acute kidney injury. - **Current guidelines recommend iso-osmolar agents as first-line** in high-risk patients with pre-existing renal impairment. *Low osmolar contrast* - **Low osmolar contrast agents** have osmolality of 600-900 mOsm/kg, which is significantly lower than high osmolar agents but still 2-3 times higher than plasma. - While **acceptable and safer than high osmolar agents**, they are not as optimal as iso-osmolar contrast for patients with renal dysfunction. - These agents are widely used and represent a reasonable alternative when iso-osmolar agents are not available. *High osmolar contrast* - **High osmolar contrast agents** have osmolality >1400 mOsm/kg (about 5 times that of plasma). - They carry the **highest risk of contrast-induced nephropathy** due to severe osmotic load and direct tubular toxicity. - **Contraindicated or strongly avoided** in patients with pre-existing renal dysfunction. *Ionic contrast* - **Ionic contrast** refers to the chemical structure (dissociates into ions) rather than osmolality. - Can be either high or low osmolar—the ionic nature alone does not determine renal safety. - The critical factor for nephrotoxicity prevention is osmolality, not ionic charge.

Q: A 25-year-old male college student presents to emergency after road traffic accident. Patient is in state of shock and breath sounds are decreased on the side of chest trauma (left side). Normal heart sounds, no elevated JVP and dull note on percussion. What is the diagnosis?

Massive Hemothorax. ***Massive Hemothorax*** - The combination of **shock**, **decreased breath sounds**, and **dullness to percussion** on the injured side is highly indicative of massive hemothorax. - A massive hemothorax involves rapid accumulation of a large volume of blood (typically >1500 mL) in the pleural space, leading to significant **hypovolemic shock** and **respiratory compromise**. *Cardiac tamponade* - Characterized by **Beck's triad**: **hypotension**, **muffled heart sounds**, and **elevated JVP**, none of which are fully present here (heart sounds are normal, JVP is not elevated). - While it can cause shock, the lung findings (decreased breath sounds, dullness) point away from a primary cardiac issue. *Flail chest* - Defined by **paradoxical chest wall movement** due to fractures of multiple adjacent ribs in two or more places, which is not mentioned in the presentation. - Although it can lead to respiratory distress, it typically presents with crepitus and localized pain, not necessarily with dullness to percussion or profound shock from blood loss. *Tension pneumothorax* - Presents with **absent or decreased breath sounds** and **hyperresonance to percussion** on the affected side, along with **tracheal deviation** away from the affected side and distended neck veins. - The key differentiating factor here is the **dullness to percussion**, which is inconsistent with the air accumulation seen in tension pneumothorax.

Question 1

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 2

Best blood product to be given in a patient of multiple clotting factor deficiency with active bleeding:

Accepted Answer

Fresh frozen plasma

Answer

Whole blood

Answer

Packed RBCs

Answer

Cryoprecipitate

Question 3

Allergic salute is seen in -

Accepted Answer

Allergic rhinitis

Answer

Nasal Myiasis

Answer

Chronic sinusitis

Answer

Chronic conjunctivitis

Question 4

A-wave in Electroretinogram corresponds to the activity of

Accepted Answer

Rods and cones

Answer

Pigment epithelium

Answer

Nerve fibre layer

Answer

Ganglion cell layer

Question 5

The site of action of the loop diuretic furosemide is:

Accepted Answer

Thick ascending limb of loop of Henle

Answer

Distal convoluted tubule

Answer

Descending limb of loop of Henle

Answer

Proximal convoluted tubule

Question 6

Which of the following is not a paraphilia?

Accepted Answer

Adultery

Answer

Necrophilia

Answer

Fetishism

Answer

Paedophilia

Question 7

Which sign on chest X-ray indicates tension pneumothorax?

Accepted Answer

Mediastinal shift

Answer

Flattened diaphragm

Answer

Deep sulcus sign

Answer

All of the options

Question 8

X-ray chest in a neonate may show 'ground glass' haziness in all the following conditions EXCEPT:

Accepted Answer

Left-to-right shunt

Answer

Obstructed TAPVC

Answer

Staphylococcal pneumonia

Answer

Hyaline membrane disease

Question 9

Which of the following contrast agents is PREFERRED in a patient with renal dysfunction for the prevention of contrast-induced nephropathy?

Accepted Answer

Iso-osmolar contrast

Answer

High osmolar contrast

Answer

Ionic contrast

Answer

Low osmolar contrast

Question 10

A 25-year-old male college student presents to emergency after road traffic accident. Patient is in state of shock and breath sounds are decreased on the side of chest trauma (left side). Normal heart sounds, no elevated JVP and dull note on percussion. What is the diagnosis?

Accepted Answer

Massive Hemothorax

Answer

Cardiac tamponade

Answer

Flail chest

Answer

Tension pneumothorax

INI-CET 2024

Biochemistry

Internal Medicine

Ophthalmology

Pharmacology

Psychiatry

Radiology

Surgery