NEET-PG 2012 Practice Questions

Q: Mechanism of cyanide poisoning is by inhibiting: NEET 2013

Cytochrome oxidase. ***Cytochrome oxidase*** - **Cyanide** is a potent poison because it binds to the **ferric iron (Fe3+)** in the active site of **cytochrome c oxidase**. - This binding completely inhibits the enzyme, halting **cellular respiration** and **ATP production**, leading to rapid cell death. *DNA synthesis* - **Cyanide** does not directly inhibit **DNA polymerase** or other enzymes involved in DNA replication. - While overall cellular processes are disrupted, its primary toxic effect is not on DNA synthesis. *Protein breakdown* - **Cyanide** does not directly interfere with proteasomes or lysosomal enzymes responsible for **protein degradation**. - Its mechanism of action is upstream, affecting energy production necessary for all cellular processes, including protein turnover. *Protein synthesis* - **Cyanide** does not directly inhibit **ribosomes** or the enzymatic machinery for **protein synthesis**. - The lack of **ATP** caused by cyanide poisoning would eventually shut down protein synthesis, but this is a secondary effect, not the primary mechanism of action.

Q: Which of the following statements is true for a left-skewed distribution?

Median > Mean. ***Median > Mean*** - In a **left-skewed distribution**, the bulk of the data is on the right, and the tail extends to the left, pulling the **mean** towards the lower values. - This pull results in the **mean** being less than the **median**, which is less affected by extreme values in the tail. *Mean = Median* - This relationship holds true for a **symmetrical distribution**, such as a **normal distribution**, where the data is evenly distributed around the center. - In a **skewed distribution**, the mean and median will diverge due to the presence of outliers or extreme values on one side. *Mean>Mode* - This statement is characteristic of a **right-skewed distribution**, where the tail extends to the right, pulling the **mean** to a higher value than the **mode**. - In a right-skewed distribution, typically **mode < median < mean**. *Mean < Mode* - This statement indicates that the **mode** (the most frequent value) is greater than the **mean**, which is not a defining characteristic of a left-skewed distribution. - While it can occur, the primary relationship for left-skewness is **mean < median**.

Q: What is the best indicator of the availability, utilization, and effectiveness of health services?

IMR. ***IMR*** - The **Infant Mortality Rate (IMR)** is widely considered the best single indicator of the availability, utilization, and effectiveness of health services because it reflects the health status of a population and the quality of prenatal, perinatal, and postnatal care. - A lower IMR generally indicates better access to maternal and child healthcare, nutrition, sanitation, and overall societal development. *MMR* - The **Maternal Mortality Ratio (MMR)** reflects the risk of maternal death relative to the number of live births and is a measure of the quality of maternal healthcare services. - While important, MMR focuses specifically on maternal health outcomes and does not encompass the broader availability and effectiveness of health services for all age groups as comprehensively as IMR. *Hospital bed OCR* - **Hospital bed occupancy rate (OCR)** indicates the proportion of available hospital beds that are occupied over a given period, reflecting the utilization of hospital resources. - While it offers insight into hospital efficiency and demand, it does not directly reflect the overall availability, effectiveness, or quality of primary care, preventive services, or broader public health interventions. *DALY* - **Disability-Adjusted Life Years (DALY)** measure the total number of healthy life years lost due to premature mortality and disability from disease or injury. - DALYs provide a comprehensive measure of disease burden but are more focused on quantifying the impact of diseases and injuries on health than on directly assessing the availability, utilization, and effectiveness of health services themselves.

Q: How many flagella does Helicobacter pylori typically have?

4-6. ***4-6*** - *Helicobacter pylori* is characterized by having **multiple flagella** (typically 4-6) at one pole, which are crucial for its motility. - These flagella allow the bacterium to move through the viscous gastric mucus layer and colonize the gastric epithelium. *1* - While some bacteria, like *Vibrio cholerae*, may possess a single polar flagellum, this is not characteristic of *Helicobacter pylori*. - A single flagellum would provide less efficient motility in the challenging environment of the stomach. *2* - Having two flagella is not the typical configuration for *Helicobacter pylori*. - Many bacteria have varied flagellar arrangements, but two is not representative of this particular bacterium. *3* - Three flagella is an insufficient number for the characteristic motility and colonization strategy of *Helicobacter pylori*. - **Lophotrichous** flagella typically refers to a tuft of multiple flagella, consistent with 4-6.

Q: How is the angle of squint measured?

Prism. ***Prism*** - The **angle of squint**, which indicates the deviation of the eyes, is most accurately measured using **prisms** in conjunction with the **prism cover test** or **alternate prism cover test**. - Prisms quantify the degree of ocular deviation in **prism diopters** by neutralizing the misalignment so that the light falls correctly on the fovea. *Gonioscopy* - This technique is used to examine the **anterior chamber angle** of the eye, which is relevant for diagnosing conditions like **glaucoma**. - It does not involve measuring the angle of ocular deviation or misalignment of the eyes. *Retinoscopy* - Retinoscopy is an objective method to determine the **refractive error** of the eye (e.g., myopia, hyperopia, astigmatism). - While it assesses the eye's ability to focus light, it does not directly measure the angle of a squint. *Keratometry* - Keratometry measures the **curvature of the cornea**, primarily used for fitting contact lenses or calculating intraocular lens power for cataract surgery. - It does not assess the alignment of the eyes or the magnitude of a squint.

Q: Which of the following is NOT typically seen in 3rd nerve palsy?

Loss of abduction. ***Loss of abduction*** - The **oculomotor nerve (CN III)** controls adduction, elevation, and depression of the eye, but **not abduction**. [2] - **Abduction** is primarily controlled by the **abducens nerve (CN VI)**, so its loss would indicate a CN VI palsy. *Mydriasis* - The **oculomotor nerve (CN III)** innervates the **parasympathetic fibers** to the pupillary constrictor muscles. [3] - Palsy of these fibers leads to unopposed action of the sympathetic dilator muscles, causing **mydriasis (pupil dilation)**. [4] *Ptosis* - The **oculomotor nerve (CN III)** innervates the **levator palpebrae superioris muscle**, which lifts the eyelid. - Dysfunction of this nerve leads to **ptosis (drooping of the eyelid)**. [1] *Loss of light reflex* - The **efferent pathway** for the **pupillary light reflex** travels via the **oculomotor nerve (CN III)** to constrict the pupil. [3] - A 3rd nerve palsy, particularly affecting the parasympathetic fibers, **impairs pupillary constriction**, resulting in a loss of the direct and consensual light reflex in the affected eye. [4]

Q: What visual disturbance is caused by an optic tract lesion?

Contralateral homonymous hemianopsia. ***Contralateral homonymous hemianopsia*** - An **optic tract lesion** interrupts the nerve fibers originating from the contralateral nasal retina and the ipsilateral temporal retina, leading to **vision loss in the contralateral visual field** of both eyes. - This results in a defect where the patient cannot see objects on the **opposite side** of the body from the lesion. *Marcus Gunn pupil* - A **Marcus Gunn pupil**, also known as an **afferent pupillary defect**, indicates asymmetric disease of the **retina** or **optic nerve**, not specifically the optic tract. - It is characterized by paradoxical dilation of the affected pupil when light is swung from the unaffected to the affected eye. *Bilateral blindness* - **Bilateral blindness** typically results from severe damage to both **optic nerves**, the **optic chiasm**, or extensive bilateral lesions in the visual cortex. - An optic tract lesion affects only one side of the visual pathway posterior to the chiasm, thus not causing complete bilateral vision loss. *Ipsilateral homonymous hemianopsia* - **Ipsilateral homonymous hemianopsia** is not a standard neurological visual field defect. Visual field defects are usually described relative to the lesion side as contralateral or ipsilateral based on the specific anatomical location. - An optic tract lesion always produces a **contralateral homonymous hemianopsia** because optic tract fibers cross at the optic chiasm.

Q: Which type of congenital cataract is commonly associated with significant visual defects?

Nuclear cataract. ***Nuclear cataract*** - It involves the **nucleus** of the lens, which is the central and most visually critical part. - This type of cataract can cause **significant visual impairment** due to its central location and density, impacting early visual development. *Punctate Cataract* - These are **small, dot-like opacities** that are usually clinically insignificant and do not typically cause significant visual defects. - They are often **peripheral** or very fine, thus not obstructing the central visual axis. *Blue dot cataract* - Also known as **cerulean cataract**, this type consists of small, bluish opacities in the lens cortex. - While congenital, it often has **minimal impact on vision** and is frequently observed incidentally. *Fusiform cataract* - This cataract forms in the shape of a **spindle or needle**, usually along the visual axis. - While it can sometimes cause minor visual compromise, its impact is generally **less severe** compared to a dense nuclear cataract.

Q: What is the antidote for Ethylene Glycol?

Fomepizole. ***Fomepizole*** - **Fomepizole** is the primary and preferred antidote for ethylene glycol poisoning, as it competitively inhibits **alcohol dehydrogenase**, the enzyme responsible for metabolizing ethylene glycol into its toxic metabolites. - By blocking this enzyme, fomepizole prevents the formation of harmful compounds like **glycolic acid** and **oxalic acid**, which cause metabolic acidosis and kidney damage. - **Ethanol** is an alternative antidote that works by the same mechanism (competitive inhibition of alcohol dehydrogenase) and can be used when fomepizole is unavailable, though fomepizole is preferred due to better safety profile and easier dosing. *Barbiturate* - **Barbiturates** are a class of psychoactive drugs that act as central nervous system depressants, primarily used for sedation, anesthesia, and seizure control. - They have no role in neutralizing or metabolizing ethylene glycol or its toxic byproducts. *Acetylcysteine* - Acetylcysteine is an antidote primarily used for **acetaminophen (paracetamol) overdose**, where it replenishes glutathione stores and detoxifies its toxic metabolite, **NAPQI**. - It does not have any direct antidotal effect against ethylene glycol or its metabolites. *Ferric chloride* - **Ferric chloride** is a chemical compound used in various industrial processes, water treatment, and as a laboratory reagent. - It is highly corrosive and toxic if ingested, but it is not used as an antidote for any type of poisoning, including ethylene glycol.

Q: Which of the following statements about Conivaptan is correct?

It is a vasopressin antagonist.. ***It is a vasopressin antagonist.*** * **Conivaptan** is a non-peptide, dual **vasopressin V1A and V2 receptor antagonist**, meaning it blocks the action of vasopressin. * By blocking vasopressin, it promotes **aquaresis** (excretion of solute-free water), which is beneficial in conditions like **hyponatremia**. * *It selectively acts on V2 receptors.* * **Conivaptan** is a **dual antagonist**, blocking both **V1A and V2 receptors**, not just V2. * **Tolvaptan**, in contrast, is a selective **V2 receptor antagonist**. * *It is administered orally.* * **Conivaptan** is typically administered intravenously, particularly in hospital settings for acute hyponatremia. * **Tolvaptan** is the orally administered vasopressin antagonist. * *All of the options.* * Since Conivaptan is not selectively acting on V2 receptors and is not administered orally, this option is incorrect.

Question 1

Mechanism of cyanide poisoning is by inhibiting: NEET 2013

Accepted Answer

Cytochrome oxidase

Answer

DNA synthesis

Answer

Protein breakdown

Answer

Protein synthesis

Question 2

Which of the following statements is true for a left-skewed distribution?

Accepted Answer

Median > Mean

Answer

Mean = Median

Answer

Mean>Mode

Answer

Mean < Mode

Question 3

What is the best indicator of the availability, utilization, and effectiveness of health services?

Accepted Answer

IMR

Answer

MMR

Answer

Hospital bed OCR

Answer

DALY

Question 4

How many flagella does Helicobacter pylori typically have?

Accepted Answer

4-6

Answer

3

Answer

2

Answer

1

Question 5

How is the angle of squint measured?

Accepted Answer

Prism

Answer

Gonioscopy

Answer

Retinoscopy

Answer

Keratometry

Question 6

Which of the following is NOT typically seen in 3rd nerve palsy?

Accepted Answer

Loss of abduction

Answer

Mydriasis

Answer

Ptosis

Answer

Loss of light reflex

Question 7

What visual disturbance is caused by an optic tract lesion?

Accepted Answer

Contralateral homonymous hemianopsia

Answer

Marcus Gunn pupil

Answer

Bilateral blindness

Answer

Ipsilateral homonymous hemianopsia

Question 8

Which type of congenital cataract is commonly associated with significant visual defects?

Accepted Answer

Nuclear cataract

Answer

Punctate Cataract

Answer

Blue dot cataract

Answer

Fusiform cataract

Question 9

What is the antidote for Ethylene Glycol?

Accepted Answer

Fomepizole

Answer

Barbiturate

Answer

Acetylcysteine

Answer

Ferric chloride

Question 10

Which of the following statements about Conivaptan is correct?

Accepted Answer

It is a vasopressin antagonist.

Answer

It selectively acts on V2 receptors.

Answer

It is administered orally.

Answer

All of the options.

NEET-PG 2012

Biochemistry

Community Medicine

Microbiology

Ophthalmology

Pharmacology