NEET-PG 2018 Practice Questions

Q: Fish odor syndrome is caused by deficiency of which enzyme?

Flavin-containing monooxygenase 3 (FMO3). ***Flavin-containing monooxygenase 3 (FMO3)*** - **Trimethylaminuria**, or "fish odor syndrome," is caused by a genetic defect in the **FMO3 enzyme**. - This enzyme is responsible for converting **trimethylamine (TMA)**, a breakdown product of certain foods, into an odorless form, **trimethylamine N-oxide (TMAO)**. *Fumarylacetoacetate hydrolase* - Deficiency in this enzyme causes **Tyrosinemia type 1**, a metabolic disorder affecting tyrosine metabolism. - It leads to severe liver disease, kidney dysfunction, and neurological crises, not a fishy body odor. *Methane monooxygenase* - This enzyme is found in certain **bacteria** (methanotrophs) and is involved in the metabolism of methane. - It is not present in humans and has no known link to human metabolic disorders like fish odor syndrome. *D-amino acid oxidase* - This enzyme is involved in the metabolism of **D-amino acids**, which are less common in mammals but found in bacteria and some foods. - Its deficiency is not associated with trimethylaminuria or a fishy body odor.

Q: Urea breath test is used for diagnosis of:

H. pylori. ***H. pylori*** - The **urea breath test** is a common and accurate non-invasive method to detect current **Helicobacter pylori** infection. - H. pylori produces the enzyme **urease**, which breaks down ingested urea into ammonia and carbon dioxide, which is then exhaled and measured. *Campylobacter jejuni* - **Campylobacter jejuni** is a common cause of **bacterial gastroenteritis** and typically diagnosed via **stool culture**. - It does not possess the **urease** enzyme, so a urea breath test would not be positive. *E.coli* - **E. coli** is a diverse group of bacteria, some strains causing gastrointestinal illness, but it is not associated with **urease production** for diagnostic purposes. - Diagnosis for diarrheagenic E. coli strains usually involves **stool culture** and specific toxin assays. *Lactobacillus* - **Lactobacillus** are beneficial bacteria commonly found in the gut and are not typically associated with pathogenic infections requiring a **urea breath test**. - They do not produce the **urease** enzyme in quantities relevant for this diagnostic test.

Q: Whole blood is used as a sample for which of the following tests?

Interferon Gamma Release Assay (IGRA). ***Interferon Gamma Release Assay (IGRA)*** - IGRAs, such as QuantiFERON-TB Gold, directly measure **interferon-gamma release** from T-lymphocytes stimulated by *Mycobacterium tuberculosis* antigens. - This test requires **fresh whole blood** as the living lymphocytes are essential for the immune response measured. *Blood Culture for Bacteria* - While blood is cultured, the primary goal is to **isolate and identify viable bacteria** from the bloodstream, not to detect an immune response within the whole blood itself. - Blood cultures typically involve placing blood into specific **culture media** to promote bacterial growth. *Genexpert* - The GeneXpert MTB/RIF assay is a **molecular test** used to detect *Mycobacterium tuberculosis* DNA and rifampicin resistance. - This assay is typically performed on **sputum samples** or other bodily fluids, not whole blood, to diagnose active tuberculosis. *Serological Test for Viruses* - Serological tests for viruses detect **antibodies or antigens** in the blood, which circulate in the **plasma or serum** component of blood. - These tests typically use **separated serum or plasma**, rather than whole blood, as the cellular components are not required for antibody or antigen detection.

Q: Sabin Feldman dye test is used for diagnosis of which of the following condition?

Toxoplasmosis. ***Toxoplasmosis*** The **Sabin-Feldman dye test** is a **serological assay** used to detect specific IgG antibodies against *Toxoplasma gondii*, the causative agent of toxoplasmosis. It measures the ability of antibodies in a patient's serum to prevent the cytoplasmic staining of live toxoplasma tachyzoites by methylene blue dye, indicating an **active immune response** to the parasite. This classic test has high sensitivity and specificity for detecting toxoplasma antibodies and is considered the gold standard serological test, though it has been largely replaced by ELISA and IFA in routine practice due to the requirement for live organisms. *Botulism* Botulism is diagnosed through **toxin detection** in serum, stool, or food samples using mouse bioassay, or by culturing *Clostridium botulinum* from clinical specimens. The Sabin-Feldman dye test is not relevant for the diagnosis of botulism, which is a **neuroparalytic disease** caused by botulinum neurotoxin blocking acetylcholine release at neuromuscular junctions. *Sarcoidosis* Sarcoidosis is a multisystem **granulomatous disease** diagnosed primarily by **tissue biopsy** showing non-caseating granulomas along with compatible clinical and radiological findings. Supportive tests include elevated serum ACE levels and Kveim test (historical). There is no serological test like the Sabin-Feldman dye test associated with the diagnosis of sarcoidosis, as it is not an infectious disease requiring antibody detection. *Yellow fever* Yellow fever is a **viral hemorrhagic disease** caused by a flavivirus, diagnosed by detecting viral RNA through RT-PCR or specific IgM antibodies in the acute phase of infection using ELISA or immunofluorescence. The Sabin-Feldman dye test is not used for viral infections like yellow fever, as it specifically targets **toxoplasma antibodies** and has no role in arboviral disease diagnosis.

Q: What is the most common symptom treated with hormone therapy (HT) in menopausal women?

Hot flashes. ***Hot flashes*** - **Vasomotor symptoms**, including hot flashes and night sweats, are the most frequent and bothersome symptoms experienced by menopausal women, leading them to seek medical attention and hormone therapy. - HT is highly effective in reducing the frequency and severity of hot flashes by stabilizing **thermoregulation** in the hypothalamus. *Breast cancer* - **Breast cancer** is a potential risk associated with hormone therapy, particularly with combined estrogen-progestin therapy, not a symptom treated by HT. - Women with a history of breast cancer or those at high risk are generally advised against HT due to this increased risk. *Endometriosis* - While **estrogen-dependent diseases** like endometriosis can be aggravated by HRT, endometriosis itself is a condition that typically improves after menopause. - HT is not used to treat endometriosis; in certain cases, it might be used to manage menopausal symptoms in women with a history of endometriosis after specific surgical interventions. *Uterine bleeding* - **Uterine bleeding** can be a side effect of hormone therapy, especially when progestin is not adequately balanced with estrogen in women with a uterus. - Abnormal uterine bleeding is a symptom that requires investigation to rule out other causes, and it is not a primary symptom treated by HT.

Q: Which is an example of Simple Myopic Astigmatism?

plano -2.00 × 90°. ***plano -2.00 × 90°*** - This prescription indicates a **spherical equivalent of zero (plano)** in one meridian and **-2.00 diopters of myopia** in the meridian 90 degrees away. - This perfectly fits the definition of **simple myopic astigmatism**, where one principal meridian is emmetropic and the other is myopic. *+2.00 sphere* - This prescription represents **simple hyperopia**, meaning the eye is **farsighted** but without any astigmatism. - All light rays focus behind the retina, and there is no difference in refractive power between the principal meridians. *-2.00 sphere* - This represents **simple myopia**, where the eye is **nearsighted** but without any astigmatism. - All light rays focus in front of the retina, and there is no difference in refractive power between the principal meridians. *+1.00 -3.00 × 90°* - This prescription is an example of **mixed astigmatism**, where one principal meridian is hyperopic (+1.00 D) and the other is myopic (-2.00 D, calculated as +1.00 + [-3.00]). - This differs from simple myopic astigmatism where one meridian is emmetropic.

Q: Struvite stones are primarily composed of which metal?

Magnesium. ***Magnesium*** - **Struvite stones** are primarily composed of **magnesium ammonium phosphate**, formed in the presence of urease-producing bacteria. - The presence of magnesium is a defining component of these **infection-related stones**. *Calcium* - **Calcium** is the primary component of the most common type of kidney stones, **calcium oxalate** and **calcium phosphate stones**. - These are typically unrelated to bacterial infections, unlike struvite stones. *Sodium* - **Sodium** is not a primary component of any common type of kidney stone. - While high sodium intake can increase the risk of stone formation, it does not directly form the stone matrix. *Potassium* - **Potassium** is not a characteristic component of kidney stones. - It plays a role in urinary pH regulation but is not directly incorporated into stone formation.

Q: Positive periodic acid-Schiff (PAS) macrophages are seen in which of the following conditions?

Whipple's disease. ***Whipple's disease*** - **Whipple's disease** is caused by the bacterium *Tropheryma whipplei*, which is ingested by macrophages and accumulates in their lysosomes [1]. - The bacterial cell wall contains **glycoproteins** and **proteoglycans** that stain magenta (red-purple) with the **periodic acid-Schiff (PAS)** stain. - PAS-positive, diastase-resistant macrophages in the lamina propria of the small intestine are **pathognomonic** for Whipple's disease [1]. *Crohn's disease* - Crohn's disease is an **inflammatory bowel disease** characterized by transmural inflammation and non-caseating granulomas. - While it involves macrophages in the inflammatory process, they do not typically show **PAS-positive inclusions**. *HIV/AIDS* - HIV/AIDS is a **viral infection** that primarily targets CD4+ T lymphocytes and macrophages. - Although macrophages are involved in HIV infection and can be found in intestinal tissue, they do not exhibit **PAS-positive inclusions** characteristic of Whipple's disease. *Celiac disease* - Celiac disease is an **autoimmune enteropathy** triggered by gluten, causing villous atrophy and malabsorption. - The histology shows increased intraepithelial lymphocytes and crypt hyperplasia, but **macrophages are not PAS-positive**. - Both Whipple's and celiac disease can present with malabsorption, making clinical differentiation important [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 798-799.

Q: What type of lesions in the skull calvarium can be identified on this X-ray?

Brain metastases. ***Brain metastases (Skull metastases)*** - The image shows multiple **lytic lesions** in the skull calvarium, which are characteristic of metastatic disease that has spread to bone - Metastases from primary cancers (lung, breast, kidney, thyroid, prostate) commonly involve the skull and appear as **punched-out or moth-eaten lytic lesions** - While plain X-rays cannot visualize brain parenchyma, they can detect **bony destruction** caused by metastatic deposits in the skull - These appear as well-defined osteolytic lesions without sclerotic margins *Multiple myeloma* - Multiple myeloma typically presents with **multiple punched-out lytic lesions** in the skull that can appear very similar to metastases - However, multiple myeloma is a **primary bone marrow malignancy** rather than metastatic disease - Key differentiator: myeloma lesions are usually more uniform in size and distribution - Clinical context (monoclonal protein, anemia, renal dysfunction) helps distinguish from metastases *Osteosarcoma* - Osteosarcoma is a **primary bone tumor** that usually causes a mixture of lytic and blastic (bone-forming) lesions - Typically presents with **sunburst or spiculated periosteal reaction** and soft tissue mass - Usually occurs as a **solitary aggressive lesion** in younger patients, not multiple scattered lesions - Rarely occurs in the skull compared to long bones *Osteomyelitis* - Osteomyelitis is an **infection of the bone** that causes bone destruction and reactive new bone formation - Shows features of **bone destruction, periosteal reaction**, and possibly sequestra (dead bone fragments) - Typically presents as a **focal process** with surrounding inflammatory changes - Does not produce the multiple discrete lytic lesions pattern seen in metastatic disease

Question 1

Fish odor syndrome is caused by deficiency of which enzyme?

Accepted Answer

Flavin-containing monooxygenase 3 (FMO3)

Answer

Fumarylacetoacetate hydrolase

Answer

Methane monooxygenase

Answer

D-amino acid oxidase

Question 2

Which of the following statements about vitamin K is correct?

Accepted Answer

Prolonged use of antimicrobials can lead to vitamin K deficiency

Answer

All of the options are true

Answer

Vitamin K acts as an anticoagulant

Answer

The recommended dietary allowance for vitamin K is 200-300 micrograms per day

Question 3

Urea breath test is used for diagnosis of:

Accepted Answer

H. pylori

Answer

E. coli

Answer

Lactobacillus

Answer

Campylobacter jejuni

Question 4

Whole blood is used as a sample for which of the following tests?

Accepted Answer

Interferon Gamma Release Assay (IGRA)

Answer

Genexpert

Answer

Blood Culture for Bacteria

Answer

Serological Test for Viruses

Question 5

Sabin Feldman dye test is used for diagnosis of which of the following condition?

Accepted Answer

Toxoplasmosis

Answer

Botulism

Answer

Sarcoidosis

Answer

Yellow fever

Question 6

What is the most common symptom treated with hormone therapy (HT) in menopausal women?

Accepted Answer

Hot flashes

Answer

Endometriosis

Answer

Uterine bleeding

Answer

Breast cancer

Question 7

Which is an example of Simple Myopic Astigmatism?

Accepted Answer

plano -2.00 × 90°

Answer

+2.00 sphere

Answer

+1.00 -3.00 × 90°

Answer

-2.00 sphere

Question 8

Struvite stones are primarily composed of which metal?

Accepted Answer

Magnesium

Answer

Calcium

Answer

Sodium

Answer

Potassium

Question 9

Positive periodic acid-Schiff (PAS) macrophages are seen in which of the following conditions?

Accepted Answer

Whipple's disease

Answer

Crohn's disease

Answer

HIV/AIDS

Answer

Celiac disease

Question 10

What type of lesions in the skull calvarium can be identified on this X-ray?

Accepted Answer

Brain metastases

Answer

Multiple myeloma

Answer

Osteosarcoma

Answer

Osteomyelitis

NEET-PG 2018

Biochemistry

Microbiology

Obstetrics and Gynecology

Ophthalmology

Pathology

Radiology