NEET-PG 2012 Practice Questions

Q: Transovarian transmission is seen in which of the following infections?

Yellow fever. ***Yellow fever*** - **Transovarian transmission** refers to the passage of a pathogen from an adult female arthropod (like a mosquito) to her offspring via the eggs. This mechanism allows the virus to persist in the **vector population** even in the absence of infected vertebrate hosts. - **Yellow fever virus** is known to undergo transovarian transmission in its mosquito vectors, particularly *Aedes aegypti* and other *Aedes* species. *Plague* - Plague is caused by the bacterium *Yersinia pestis* and is primarily transmitted by **flea bites** from infected rodents to humans. - It does not involve transovarian transmission; the fleas acquire the bacteria during a **blood meal** from an infected host. *Ebola fever* - Ebola virus is transmitted through **direct contact** with blood or bodily fluids of infected humans or animals. - It is not an **arthropod-borne disease** and therefore does not exhibit transovarian transmission. *None of the options* - This option is incorrect because **Yellow Fever** clearly demonstrates transovarian transmission within its mosquito vector.

Q: What is the most commonly reported bacterial sexually transmitted infection?

Chlamydia. ***Correct: Chlamydia*** - **Chlamydia trachomatis** is the most frequently reported bacterial STI in many countries, often being **asymptomatic** and thus easily spread - Its high prevalence is due to efficient transmission and the widespread use of sensitive diagnostic tests that detect infections in asymptomatic individuals - Accounts for the majority of reported bacterial STI cases globally *Incorrect: HSV* - **Herpes Simplex Virus (HSV)** is a **viral STI**, not bacterial, and is characterized by recurrent outbreaks of **genital ulcers** or sores - While common, it does not qualify as a bacterial infection and is often not laboratory-confirmed due to mild or subclinical presentations *Incorrect: HIV* - **Human Immunodeficiency Virus (HIV)** is also a **viral STI**, not bacterial, that attacks the immune system leading to AIDS - Although highly impactful, HIV is not a bacterial infection and has lower incidence rates compared to Chlamydia *Incorrect: Syphilis* - **Syphilis**, caused by the bacterium **Treponema pallidum**, is a serious bacterial STI that can have long-term complications if untreated - While its incidence has been increasing in some regions, it is significantly less common than **Chlamydia** in terms of overall reported cases

Q: Which occupational exposure may cause sterility in females ?

Agricultural insecticides. ***Agricultural insecticides*** - Exposure to **organochlorine** and **organophosphate** insecticides can have significant **reproductive toxicity** in females, leading to **infertility** or **sterility**. - These chemicals can disrupt **hormonal balance**, interfere with **ovarian function**, cause **menstrual irregularities**, and lead to **developmental toxicity** in offspring. - Well-documented occupational hazard in agricultural workers with chronic exposure. *Lead* - Lead is a well-established **reproductive toxicant** affecting **both males and females**. - In females, lead causes **menstrual irregularities**, **ovarian dysfunction**, **reduced fertility**, **spontaneous abortions**, and can contribute to sterility. - It disrupts the **hypothalamic-pituitary-ovarian axis** and has direct **gonadotoxic effects**. - While agricultural insecticides are more specifically associated with female sterility in occupational contexts, lead is also a significant reproductive hazard. *Carbon monoxide* - Carbon monoxide poisoning primarily causes **hypoxia** by binding to hemoglobin, forming **carboxyhemoglobin**. - It does not directly cause **sterility** in females; its main reproductive concern relates to **fetal hypoxia** and adverse pregnancy outcomes during exposure. *Mercury* - Mercury exposure, particularly **methylmercury**, is a known **neurotoxin** and can cause **developmental abnormalities**. - While it can affect pregnancy outcomes and cause **menstrual disorders** at high exposures, it is not typically cited as a primary occupational cause of **female sterility** compared to agricultural insecticides.

Q: Ataxia, nystagmus, and ophthalmoplegia are seen in which of the following conditions?

Wernicke encephalopathy. ***Wernicke encephalopathy*** - This condition is characterized by the classic triad of **ataxia**, **nystagmus**, and **ophthalmoplegia** (often presenting as external ophthalmoplegia), alongside confusion [2]. - It results from a **thiamine (vitamin B1) deficiency** [2], [3], commonly seen in chronic alcoholics or individuals with severe malnutrition. *Myasthenia gravis* - This is an **autoimmune disorder** affecting the neuromuscular junction, leading to fluctuating muscle weakness that worsens with activity [1]. - While it can cause **ophthalmoplegia** (especially ptosis and diplopia), it does not typically present with ataxia or nystagmus. *3rd nerve palsy* - A **third nerve palsy** specifically affects the oculomotor nerve, causing a constellation of symptoms including ptosis, pupillary dilation, and inability to move the eye up, down, or medially. - While it causes **ophthalmoplegia** affecting one eye, it does not typically cause nystagmus or ataxia. *Chronic progressive external ophthalmoplegia* - This is a mitochondrial disorder characterized by **slowly progressive weakness** of the extraocular muscles, leading to bilateral ptosis and limitation of eye movements. - It causes a specific type of **ophthalmoplegia** but is not typically associated with nystagmus or prominent ataxia.

Q: Which of the following Trichophyton species is known to be zoophilic?

T. mentagrophytes. ***T. mentagrophytes*** - This species is well-known for being **zoophilic**, meaning it primarily infects animals but can be transmitted to humans. - It is a common cause of **tinea corporis** (ringworm of the body), **tinea pedis** (athlete's foot), and **tinea barbae**, often contracted from contact with infected pets or farm animals. *T. tonsurans* - This is an **anthropophilic** species, meaning it primarily infects humans. - It is a leading cause of **tinea capitis** (ringworm of the scalp) in the United States, particularly among children, and typically presents with a "black dot" appearance. *T. violaceum* - This is another **anthropophilic** species, endemic in various parts of the world, especially the Middle East and Africa. - It also causes **tinea capitis** and can lead to a characteristic "gray patch" type of infection. *T. schoenleinii* - This is an **anthropophilic** species historically associated with **favus**, a severe form of tinea capitis. - Favus is characterized by the formation of sulfur-yellow, cup-shaped crusts called **scutula** and can lead to permanent hair loss and scarring.

Q: Influenza virus culture is done on ?

Allantoic cavity. ***Allantoic cavity*** - The **allantoic cavity** of embryonated chicken eggs is the standard and most effective site for isolating and propagating **influenza viruses** for vaccine production and research. - This cavity provides an optimal environment for viral replication, particularly yielding high titers of **hemagglutinin**, a key influenza antigen. *Chorioallantoic membrane* - While embryonated eggs are used for virus culture, the **chorioallantoic membrane (CAM)** is primarily used for cultivating viruses that produce **pocks** (visible lesions), such as Vaccinia and Herpes Simplex Virus. - Influenza virus growth on the CAM is less efficient and typically doesn't produce distinct pocks, making it unsuitable for high-yield propagation compared to the allantoic cavity. *Yolk sac* - The **yolk sac** of embryonated eggs is ideal for growing viruses or bacteria that require a **lipid-rich environment** and replicate intracellularly, such as Chlamydia or Rickettsia. - It is not the preferred site for influenza virus isolation or proliferation due to suboptimal conditions for viral replication and lower viral yields. *All of the options* - While all these sites are components of an embryonated chicken egg, each serves as a host for different types of microorganisms or for specific purposes in virology. - For **influenza virus culture**, the **allantoic cavity** is the specifically utilized site for optimal growth and high viral yield.

Q: What condition is characterized by cherry red spot at the macula with retinal whitening?

CRAO. ***CRAO*** - **Central retinal artery occlusion (CRAO)** is characterized by **sudden, profound, painless monocular vision loss**. - The classic funduscopic finding is a **cherry-red spot at the macula** with diffuse **retinal whitening** due to ischemia. *CRVO* - **Central retinal vein occlusion (CRVO)** presents with **painless vision loss** but typically shows **hemorrhages**, **dilated tortuous veins**, and **cotton wool spots** on funduscopic exam. - It does not usually cause retinal whitening or a cherry-red spot. *Diabetic retinopathy* - **Diabetic retinopathy** is characterized by **microaneurysms**, **hemorrhages**, **hard exudates**, and **cotton wool spots**, and can lead to neovascularization. - It does not present with acute retinal whitening or a cherry-red spot in the macula. *Syphilitic retinopathy* - **Syphilitic retinopathy** can cause a variety of presentations, including **retinal vasculitis**, **chorioretinitis**, and **optic neuritis**. - It does not typically manifest as a cherry-red spot with diffuse retinal whitening at the macula.

Q: What is the first clinical sign observed in a patient with anterior uveitis?

Presence of aqueous flare. ***Presence of aqueous flare*** - **Aqueous flare** is considered the **earliest clinical sign** of anterior uveitis, representing increased protein content in the anterior chamber due to breakdown of the **blood-aqueous barrier**. - It is detected as a visible "haze" when a **slit lamp beam** passes through the anterior chamber, similar to observing dust particles in a light beam. *Presence of hypopyon* - **Hypopyon** is a more severe sign, indicating a **layer of white blood cells** in the anterior chamber, representing a more advanced inflammatory process. - While it can occur in severe anterior uveitis, it is not typically the **first or earliest** clinical manifestation. *Presence of miosis* - **Miosis** (pupillary constriction) can be present in anterior uveitis due to **iris inflammation** and irritation of the sphincter muscle. - However, it is an indirect sign and typically occurs *after* the initial signs of inflammation in the aqueous humor, such as flare. *Presence of keratic precipitates* - **Keratic precipitates (KPs)** are deposits of inflammatory cells on the **endothelium of the cornea**. - These deposits are a result of sustained inflammation and typically appear *after* the initial inflammatory changes in the aqueous humor, such as flare, have already occurred.

Q: Which diuretic exhibits paradoxical antidiuretic activity in diabetes insipidus?

Thiazide diuretics. ***Thiazide diuretics*** - Thiazides cause a modest **volume depletion**, leading to increased proximal tubular reabsorption of water and solutes [1]. - They also lower the **glomerular filtration rate**, further reducing the amount of fluid delivered to the collecting ducts, thus paradoxically reducing urine output in diabetes insipidus [2]. - This effect is particularly useful in **nephrogenic diabetes insipidus**, where the kidneys cannot respond to ADH [2]. *Potassium-sparing diuretics (Triamterene)* - Triamterene is a **potassium-sparing diuretic** that blocks epithelial sodium channels in the late distal tubule and collecting duct. - It increases sodium and water excretion, which would worsen, not improve, the polyuria of diabetes insipidus. *Aldosterone antagonists (Spironolactone)* - Spironolactone is a **mineralocorticoid receptor antagonist** that increases sodium and water excretion while conserving potassium in the collecting duct. - Its primary action is to counteract aldosterone, and it does not exhibit the paradoxical antidiuretic effect seen with thiazides in diabetes insipidus. *Loop diuretics (Furosemide)* - Loop diuretics like furosemide act on the **thick ascending limb of the loop of Henle** to inhibit sodium, potassium, and chloride reabsorption. - They cause significant diuresis and would **exacerbate the polyuria** in patients with diabetes insipidus, rather than improving it.

Q: Which of the following statements about vinca alkaloids is true?

Inhibits mitotic spindle. ***Inhibits mitotic spindle*** - **Vinca alkaloids** (e.g., vincristine, vinblastine) exert their cytotoxic effects by binding to **tubulin**, thereby inhibiting its polymerization into microtubules. - This disruption prevents the formation of the **mitotic spindle**, arresting cells in metaphase and leading to apoptosis. *Enhances polymerization of tubulin* - This statement describes the mechanism of action of **taxanes** (e.g., paclitaxel), which stabilize microtubules and prevent their depolymerization. - Vinca alkaloids, in contrast, **inhibit** tubulin polymerization, preventing microtubule assembly. *Inhibits topoisomerase I* - Inhibition of **topoisomerase I** is the mechanism of action for drugs like **irinotecan** and **topotecan**. - These agents cause single-strand breaks in DNA, which is distinct from the microtubule disruption caused by vinca alkaloids. *Inhibits topoisomerase II* - Drugs like **etoposide** and **teniposide** work by inhibiting **topoisomerase II**, leading to double-strand DNA breaks. - This mechanism is different from the disruption of microtubule dynamics seen with vinca alkaloids.

Question 1

Transovarian transmission is seen in which of the following infections?

Accepted Answer

Yellow fever

Answer

Plague

Answer

Ebola fever

Answer

None of the options

Question 2

What is the most commonly reported bacterial sexually transmitted infection?

Accepted Answer

Chlamydia

Answer

HSV

Answer

HIV

Answer

Syphilis

Question 3

Which occupational exposure may cause sterility in females ?

Accepted Answer

Agricultural insecticides

Answer

Lead

Answer

Carbon monoxide

Answer

Mercury

Question 4

Ataxia, nystagmus, and ophthalmoplegia are seen in which of the following conditions?

Accepted Answer

Wernicke encephalopathy

Answer

3rd nerve palsy

Answer

Myasthenia gravis

Answer

Chronic progressive external ophthalmoplegia

Question 5

Which of the following Trichophyton species is known to be zoophilic?

Accepted Answer

T. mentagrophytes

Answer

T. tonsurans

Answer

T. violaceum

Answer

T. schoenleinii

Question 6

Influenza virus culture is done on ?

Accepted Answer

Allantoic cavity

Answer

Chorioallantoic membrane

Answer

Yolk sac

Answer

All of the options

Question 7

What condition is characterized by cherry red spot at the macula with retinal whitening?

Accepted Answer

CRAO

Answer

CRVO

Answer

Diabetic retinopathy

Answer

Syphilitic retinopathy

Question 8

What is the first clinical sign observed in a patient with anterior uveitis?

Accepted Answer

Presence of aqueous flare

Answer

Presence of hypopyon

Answer

Presence of miosis

Answer

Presence of keratic precipitates

Question 9

Which diuretic exhibits paradoxical antidiuretic activity in diabetes insipidus?

Accepted Answer

Thiazide diuretics

Answer

Aldosterone antagonists (Spironolactone)

Answer

Loop diuretics (Furosemide)

Answer

Potassium-sparing diuretics (Triamterene)

Question 10

Which of the following statements about vinca alkaloids is true?

Accepted Answer

Inhibits mitotic spindle

Answer

Enhances polymerization of tubulin

Answer

Inhibits topoisomerase I

Answer

Inhibits topoisomerase II

NEET-PG 2012

Community Medicine

Internal Medicine

Microbiology

Ophthalmology

Pharmacology