NEET-PG 2020 Practice Questions

Q: When the insulin:glucagon ratio is decreased, which enzyme is active?

Glucose-6-phosphatase. ***Glucose-6-phosphatase*** - A decreased insulin:glucagon ratio indicates a **fasting state** or **catabolic state**, promoting glucose production and release rather than storage. - **Glucose-6-phosphatase** is the key enzyme that enables glucose release from the liver by removing the phosphate group from glucose-6-phosphate, producing free glucose that can exit hepatocytes. - This enzyme is active during both **gluconeogenesis** and **glycogenolysis** and is only present in liver, kidney, and intestinal cells. *Glucokinase* - **Glucokinase** is active in the **fed state** when insulin levels are high and the insulin:glucagon ratio is increased. - It phosphorylates glucose to trap it in hepatocytes for glycogen synthesis and metabolism, which is the opposite of what occurs during fasting. *Phosphofructokinase* - **Phosphofructokinase (PFK-1)** is the rate-limiting enzyme of **glycolysis**, active when glucose needs to be broken down for energy. - It is stimulated by high insulin:glucagon ratios and inhibited during fasting when gluconeogenesis (the reverse pathway) is active. *Hexokinase* - **Hexokinase** phosphorylates glucose in peripheral tissues for intracellular utilization. - During a low insulin:glucagon ratio, the priority is glucose **release** from the liver, not glucose **uptake** and phosphorylation in tissues.

Q: Partial and full closure of nasal passages is characteristically seen in:

Vasomotor rhinitis. ***Vasomotor rhinitis*** - This condition is characterized by **vascular dysregulation** in the nasal mucosa, leading to episodic **swelling** and **congestion** that can result in partial or full nasal closure without an identifiable allergic or infectious cause. - Symptoms are often triggered by **non-specific irritants** like temperature changes, strong odors, or emotional stress, causing the nasal blood vessels to dilate excessively. *Allergic rhinitis* - While it causes nasal congestion and obstruction, the primary mechanism is an **IgE-mediated inflammatory response** to specific allergens, leading to mucosal edema and increased mucus production. - The closure is typically accompanied by other allergic symptoms such as **sneezing**, **itching**, and **rhinorrhea**, which differentiates it from vasomotor rhinitis. *Atrophic rhinitis* - This condition involves **progressive atrophy** of the nasal mucosa, turbinates, and underlying bone, resulting in an abnormally wide nasal passage rather than obstruction. - Patients typically experience **paradoxical nasal obstruction** due to altered airflow dynamics and crusting, alongside a characteristic foul odor. *Occupational rhinitis* - This type of rhinitis is caused by **exposure to specific agents** in the workplace, leading to inflammation and nasal obstruction, often accompanied by sneezing and rhinorrhea. - Symptom onset is directly linked to **workplace exposure** and improves away from the occupational environment, which is not suggested by the general term "partial and full closure."

Q: A 35-year-old heterosexual patient diagnosed with HIV presents with watery diarrhea. The colonoscopic biopsy is shown below. Which of the following is your most probable diagnosis?

Cryptosporidium. ***Cryptosporidium*** - The image shows numerous small, round **Cryptosporidium oocysts** lining the **brush border** of the intestinal epithelial cells, a classic histological finding in disseminated disease in immunocompromised patients. - In an HIV patient with watery diarrhea, **Cryptosporidiosis** is a common opportunistic infection, especially when CD4 counts are low. *Giardia* - **Giardia lamblia** typically appears as teardrop-shaped trophozoites or oval cysts. Trophozoites would be motile in stool samples or adhere to the brush border but are much larger and morphologically distinct from the structures seen here. - While it causes watery diarrhea, the histological appearance does not match the small, bead-like structures on the epithelial surface. *CMV* - **Cytomegalovirus (CMV)** infection in the gut would typically show **cytomegalic cells** with characteristic **intranuclear inclusions** (owl's eye inclusions) and sometimes intracytoplasmic inclusions within various cell types, including endothelial cells and fibroblasts. - The image does not display these large, virally infected cells or inclusion bodies; instead, it shows numerous small parasitic forms on the surface. *Microsporidia* - **Microsporidia** are intracellular parasites that infect enterocytes and cause watery diarrhea in HIV patients. They are extremely small and often require special stains (e.g., modified trichrome, Warthin-Starry silver stain) or electron microscopy for definitive identification. - While they are small, the parasites in the image appear more superficial and exhibit a distinct spherical shape consistent with *Cryptosporidium* oocysts rather than the typically intracellular, punctate forms of microsporidia, which are harder to see with routine H&E staining without significant intracellular disruption.

Q: Transplantation between identical twins-

Isograft. ***Isograft*** - An **isograft** refers to a transplant between **genetically identical individuals**, such as identical twins, thus minimizing immune rejection [1]. - Due to the identical genetic makeup, the recipient's immune system will not recognize the transplanted tissue as foreign, making **immunosuppression unnecessary** [1]. *Xenograft* - A **xenograft** involves transplantation of tissues or organs between **different species**, for example, from a pig to a human. - These grafts typically face severe and rapid **immune rejection** due to significant genetic differences between the donor and recipient species. *Autograft* - An **autograft** is a transplant of tissue from **one part of an individual's body to another part of the same individual**. - This type of graft has no risk of rejection as the tissue is genetically identical to the recipient's own tissue [2]. *Allograft* - An **allograft** is a transplant between **genetically non-identical individuals of the same species**, such as between two non-twin humans. - These grafts always require **immunosuppressive therapy** to prevent rejection due to genetic differences, though rejection rates vary based on HLA matching [1].

Q: Cancer patient undergoes radiotherapy, pick the true statement for radiosensitivity of tissues?

Small blood vessels are radiosensitive tissues. ***Small blood vessels are radiosensitive tissues*** - **Endothelial cells** lining small blood vessels are actively dividing and have a relatively short lifespan, making them susceptible to radiation-induced damage. - Damage to these vessels can lead to **fibrosis** and **tissue hypoxia**, contributing to late radiation effects. *GI mucosa is one of the most radioresistant tissues in the body* - The **GI mucosa** is one of the **most radiosensitive** tissues due to its rapid cell turnover and high proliferative capacity, leading to symptoms like mucositis and diarrhea after radiation. - The constant renewal of epithelial cells makes them highly vulnerable to the **cytotoxic effects** of radiation. *Rapidly dividing cells are resistant to radiation* - **Rapidly dividing cells**, such as those in the bone marrow, GI crypts, and hair follicles, are generally **most sensitive** to radiation. - This forms the basis of radiation therapy, as cancer cells often have a higher proliferative rate than many normal tissues, making them a target. *The intensity of radiation is inversely proportional to the square of distance from the source* - This statement describes the **inverse square law** for radiation intensity, which is true, but it is a principle of radiation physics, not a statement about the radiosensitivity of tissues. - The inverse square law dictates how radiation dose **attenuates with distance**, which is critical for dose calculation but not directly about biological radiosensitivity.

Q: In the primary survey, which of the following is not included?

CECT to look for bleeding. ***CECT to look for bleeding*** - A **CECT scan** is a detailed imaging study that is performed during the **secondary survey**, not during the primary survey. - The primary survey focuses on the immediate **ABCDE assessment** (Airway, Breathing, Circulation, Disability, Exposure) to identify and treat immediately life-threatening conditions. - While identifying bleeding is critical, detailed imaging like CECT is done only after initial stabilization is achieved in the primary survey. *ABC* - **Airway, Breathing, and Circulation (ABC)** are the fundamental first three components of the primary survey. - These represent the immediate priorities for life support in trauma management according to ATLS guidelines. - Ensuring a patent airway, adequate breathing, and circulatory stability are critical first steps. *Exposure of the whole body* - **Exposure** (the "E" in ABCDE) is an essential part of the primary survey. - Complete exposure allows full assessment for injuries and prevents missing critical external wounds. - This step also involves maintaining **thermoregulation** to prevent hypothermia. *Recording BP* - **Recording blood pressure** is a crucial part of assessing circulation (the "C") during the primary survey. - It helps quickly evaluate hemodynamic status and identify potential signs of shock or internal bleeding. - Vital signs monitoring is integral to the initial trauma assessment.

Question 1

When the insulin:glucagon ratio is decreased, which enzyme is active?

Accepted Answer

Glucose-6-phosphatase

Answer

Glucokinase

Answer

Phosphofructokinase

Answer

Hexokinase

Question 2

Partial and full closure of nasal passages is characteristically seen in:

Accepted Answer

Vasomotor rhinitis

Answer

Allergic rhinitis

Answer

Atrophic rhinitis

Answer

Occupational rhinitis

Question 3

A 35-year-old heterosexual patient diagnosed with HIV presents with watery diarrhea. The colonoscopic biopsy is shown below. Which of the following is your most probable diagnosis?

Accepted Answer

Cryptosporidium

Answer

Giardia

Answer

CMV

Answer

Microsporidia

Question 4

Transplantation between identical twins-

Accepted Answer

Isograft

Answer

Xenograft

Answer

Autograft

Answer

Allograft

Question 5

Cancer patient undergoes radiotherapy, pick the true statement for radiosensitivity of tissues?

Accepted Answer

Small blood vessels are radiosensitive tissues

Answer

GI mucosa is one of the most radioresistant tissues in the body

Answer

Rapidly dividing cells are resistant to radiation

Answer

The intensity of radiation is inversely proportional to the square of distance from the source

Question 6

In the primary survey, which of the following is not included?

Accepted Answer

CECT to look for bleeding

Answer

ABC

Answer

Exposure of the whole body

Answer

Recording BP

NEET-PG 2020

Biochemistry

ENT

Microbiology

Pathology

Radiology

Surgery