NEET-PG 2015 Practice Questions

Q: Blood testis barrier in testis is formed by?

Sertoli cells. ***Sertoli cells*** - **Sertoli cells** form tight junctions with each other, creating the **blood-testis barrier** [1] - This barrier divides the seminiferous epithelium into **basal and adluminal compartments** [1] - Essential for protecting developing **germ cells** from immune attack and maintaining a specialized microenvironment for **spermatogenesis** [1] - The tight junctions between Sertoli cells are among the tightest in the human body *Granulosa cells* - **Granulosa cells** are found in the **ovary**, not the testis - They surround the oocyte in ovarian follicles and produce **estrogen** - Completely unrelated to testicular structure or function *Germ cells* - **Germ cells** (spermatogonia, spermatocytes, spermatids, spermatozoa) are the developing sperm cells [1] - They are **protected by** the blood-testis barrier, not forming it [1] - Located within the seminiferous tubules but do not create barrier structures [1] *Leydig cells* - **Leydig cells** are interstitial cells located in the connective tissue **between seminiferous tubules** - Their primary function is production of **testosterone**, not forming barriers [2] - They are outside the seminiferous tubules and not involved in barrier formation [2]

Q: Bile acids are synthesized from ?

Cholesterol. ***Cholesterol*** - **Bile acids** are derivatives of **cholesterol**, synthesized in the liver through a multi-step enzymatic pathway. - The conversion of cholesterol to bile acids is a primary mechanism for the excretion and transport of cholesterol from the body. *Heme* - **Heme** is a component of hemoglobin and myoglobin, primarily involved in oxygen transport and storage. - Its degradation product is **bilirubin**, which forms part of bile but is distinct from bile acids. *Ribulose* - **Ribulose** is a 5-carbon sugar, playing a key role in the **pentose phosphate pathway** and the **Calvin cycle** in photosynthesis. - It is not a precursor for bile acid synthesis. *Arachidonic acid* - **Arachidonic acid** is a polyunsaturated fatty acid that serves as a precursor for **eicosanoids** (prostaglandins, thromboxanes, and leukotrienes). - These molecules are involved in inflammation and immune responses but are unrelated to bile acid synthesis.

Q: Enzyme activity is expressed as?

Micromoles/min. ***Micromoles/min*** - Enzyme activity is typically measured by the rate at which an enzyme converts its **substrate into product**. - This rate is often expressed as the amount of product formed (e.g., **micromoles**) or substrate consumed per unit of time (e.g., **per minute**). *Millimoles/lit* - This unit expresses **concentration** (moles per liter) rather than a rate of reaction. - While enzyme reactions involve changes in substrate/product concentration, this unit alone does not describe the **activity or catalytic speed** of the enzyme. *Milli gm/lit* - This unit also expresses **concentration by mass** (milligrams per liter), not enzyme activity. - It does not account for the **time-dependent nature** of enzyme catalysis or the molar quantity of reactants/products. *Mg/dl* - This unit represents **concentration by mass** (milligrams per deciliter), commonly used for measuring substances like glucose or cholesterol in blood. - It is not appropriate for expressing the **catalytic rate or activity** of an enzyme.

Q: Which of the following processes primarily utilizes lactate produced anaerobically?

Cori cycle. ***Cori cycle*** - The **Cori cycle** (lactic acid cycle) involves the transport of **lactate** produced during anaerobic metabolism in muscles to the liver. - In the **liver**, this lactate is then converted back to **glucose** via gluconeogenesis, which can be returned to the muscles. *Gluconeogenesis* - **Gluconeogenesis** is the synthesis of glucose from non-carbohydrate precursors, one of which is lactate. - While it uses lactate, it is only one component of the broader **Cori cycle**, which describes the inter-organ cooperation. *Glycolysis* - **Glycolysis** is the metabolic pathway that breaks down glucose into pyruvate, which can then be converted to lactate under anaerobic conditions. - This process *produces* lactate but does not *utilize* it, acting upstream of lactate production. *TCA cycle* - The **TCA cycle** (Krebs cycle) is a central part of aerobic respiration that oxidizes acetyl-CoA to produce ATP, NADH, and FADH2. - It does not directly utilize lactate; instead, lactate is typically converted to pyruvate before potentially entering the TCA cycle under aerobic conditions.

Q: Base of sphenoid fuses with occiput at the age of -

20 years. ***20 years*** - The **spheno-occipital synchondrosis** typically fuses by the age of **20 to 25 years**, marking the cessation of growth in the cranial base. - This fusion is an important indicator of skeletal maturity and is often used in **forensic anthropology** for age estimation. *30 years* - Fusion of the **spheno-occipital synchondrosis** beyond the early twenties is considered late and is not the typical age for this event. - By 30 years, most cranial sutures and synchondroses are already fused. *40 years* - At 40 years of age, the **spheno-occipital synchondrosis** would have been completely fused for many years, making this an incorrect age for the fusion process itself. - This age is well past the usual developmental timeframe for cranial base closure. *50 years* - Fusion at 50 years would be an **anomalous finding** as this synchondrosis is known to fuse much earlier in life. - By this age, the skull is fully mature, and fusion events of this nature have long since completed.

Q: In which condition is the Doll's Eye Reflex tested?

Unconscious patients. ***Unconscious patients*** - The **Doll's Eye Reflex**, also known as the **oculocephalic reflex**, is a brainstem reflex used to assess brainstem function in **comatose or unconscious patients** [1]. - It is positive if the eyes move in the opposite direction to the head turn, indicating intact brainstem pathways [1]. *Hemiplegic* - **Hemiplegia** refers to paralysis on one side of the body, often due to stroke or brain injury. - While it can be associated with altered consciousness, the Doll's Eye Reflex specifically tests brainstem integrity in unconscious states, not the motor deficits of hemiplegia itself. *Paraplegic* - **Paraplegia** is paralysis affecting the lower half of the body. - This condition primarily involves spinal cord damage and does not directly relate to the assessment of brainstem function using the Doll's Eye Reflex. *Cerebral palsy* - **Cerebral palsy** is a group of disorders affecting movement, muscle tone, or posture, caused by damage to the developing brain. - While individuals with cerebral palsy may have neurological impairments, the Doll's Eye Reflex is not a primary diagnostic or assessment tool for this chronic condition; it is used acutely in unconscious states.

Q: Diabetic foot is associated with following type of gangrene -

Wet gangrene. ***Wet gangrene*** - Diabetic foot commonly leads to **ischemia** and **infection** [1], resulting in wet gangrene characterized by moist, necrotic tissue. - This type of gangrene is associated with **rapid progression** and can result in systemic toxicity, making prompt treatment essential. *Fournier's gangrene* - This type of gangrene specifically affects the **perineal** region and is not directly associated with diabetic foot. - It usually arises from infections related to **perineal trauma** or surgical procedures. *Gas gangrene* - Caused by **Clostridium** species and typically follows a traumatic injury or surgical procedure, not specifically related to diabetes. - Presents with **crepitus** and rapid systemic symptoms, different from the chronic nature of diabetic ulcers. *Dry gangrene* - Associated with **chronic ischemia** and necrosis, it occurs in conditions like peripheral arterial disease, not primarily with infections seen in diabetic foot [1]. - It usually develops gradually without the sudden onset of symptoms characteristic of wet gangrene.

Q: What does Ghon's focus indicate in the context of tuberculosis?

Primary complex. ***Primary complex*** - A **Ghon's focus** is the initial parenchymal lesion (typically subpleural) that develops during primary tuberculosis infection [1]. - The Ghon's focus, together with an enlarged regional lymph node (usually hilar or mediastinal), forms the **Ghon's complex** or **Primary complex** [2]. - When this complex undergoes calcification and healing, it is called a **Ranke complex**, which indicates past healed primary TB. *Post primary tuberculosis* - Also known as **reactivation tuberculosis** or **secondary tuberculosis**, this typically occurs years after the primary infection, usually in the apices of the lungs [2]. - It represents reactivation of dormant bacilli, not the initial primary infection lesion. - Characterized by cavitary lesions and often more severe pulmonary symptoms. *Miliary tuberculosis* - This is a form of progressive, widespread tuberculosis characterized by the presence of **tiny, millet-seed sized lesions** disseminated throughout the body via hematogenous spread [3]. - It indicates a severe and life-threatening form of TB resulting from massive lymphohematogenous dissemination. - Not related to the localized primary complex. *Tuberculous lymphadenitis* - This refers to **tuberculous infection of lymph nodes**, most commonly in the cervical region (scrofula). - While lymph node involvement is part of the primary complex, Ghon's focus specifically refers to the **parenchymal lung lesion**, not the lymph node component alone [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 379-380. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 319-320. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 320-321.

Q: IgA nephropathy is not associated with which of the following?

Decreased complement level. ***Decreased complement level*** - IgA nephropathy is typically associated with **normal serum complement levels** (C3 and C4), which is an important distinguishing feature. - Unlike post-streptococcal glomerulonephritis or lupus nephritis where complement levels are **low/decreased**, IgA nephropathy does not cause systemic complement consumption. - While complement activation does occur locally in the glomerulus (via lectin and alternative pathways), it does not lead to a decrease in serum complement levels. *Focal mesangial proliferation* - This is a **common histological finding** in IgA nephropathy, reflecting the proliferative response to IgA deposition in the mesangium. - The mesangial cells proliferate in an attempt to clear the immune deposits. *Gross hematuria concurrent with upper respiratory infection* - This is a **classic clinical presentation** of IgA nephropathy, often referred to as **synpharyngitic hematuria**. - The episode of gross hematuria typically occurs **within 1-2 days** of the onset of an upper respiratory tract infection, distinguishing it from post-streptococcal glomerulonephritis where hematuria appears 1-3 weeks later. *Immunofluorescence deposits contain IgA and IgG* - The defining feature of IgA nephropathy on immunofluorescence is the **predominant deposition of IgA**, often accompanied by C3. - While IgA is the primary immunoglobulin, **IgG and IgM can also be present** in variable amounts, but IgA must be the dominant or co-dominant immunoglobulin for the diagnosis.

Q: Lines of Zahn are LEAST likely to be seen in -

Lung. ***Lung*** - **Lines of Zahn are LEAST likely in the lungs** because most pulmonary thrombi are actually **emboli that formed elsewhere** (typically in deep leg veins) and then **lodged in pulmonary vessels**. - These pre-formed thrombi developed in **low-flow venous environments** and therefore **lack the characteristic layered appearance** of Lines of Zahn. - Even when thrombi form in situ in pulmonary vessels, the vascular bed characteristics make Lines of Zahn formation less common compared to other sites. *Heart* - **Mural thrombi** in heart chambers (especially post-MI in left ventricle or in atrial fibrillation) commonly show **Lines of Zahn**. - The **high-flow, turbulent environment** with continuous cardiac contractions creates ideal conditions for alternating platelet-fibrin and RBC layer deposition. - These are classic examples of antemortem thrombi with visible Lines of Zahn. *Liver* - **Portal vein thrombosis** and **hepatic vein thrombosis** (Budd-Chiari syndrome) can exhibit **Lines of Zahn**. - Despite being venous, these vessels have **sufficient flow velocity and turbulence** to allow layered thrombus formation. - Lines of Zahn indicate the thrombus formed during life with flowing blood. *Kidney* - **Renal artery thrombosis** and **renal vein thrombosis** frequently show **Lines of Zahn**. - Both arterial and venous renal circulation have adequate flow dynamics for layered thrombus formation. - These represent antemortem thrombi formed in vessels with active blood flow.

Question 1

Blood testis barrier in testis is formed by?

Accepted Answer

Sertoli cells

Answer

Germ cells

Answer

Leydig cells

Answer

Granulosa cells

Question 2

Bile acids are synthesized from ?

Accepted Answer

Cholesterol

Answer

Heme

Answer

Ribulose

Answer

Arachidonic acid

Question 3

Enzyme activity is expressed as?

Accepted Answer

Micromoles/min

Answer

Millimoles/lit

Answer

Milli gm/lit

Answer

Mg/dl

Question 4

Which of the following processes primarily utilizes lactate produced anaerobically?

Accepted Answer

Cori cycle

Answer

Gluconeogenesis

Answer

TCA cycle

Answer

Glycolysis

Question 5

Base of sphenoid fuses with occiput at the age of -

Accepted Answer

20 years

Answer

30 years

Answer

40 years

Answer

50 years

Question 6

In which condition is the Doll's Eye Reflex tested?

Accepted Answer

Unconscious patients

Answer

Hemiplegic

Answer

Paraplegic

Answer

Cerebral palsy

Question 7

Diabetic foot is associated with following type of gangrene -

Accepted Answer

Wet gangrene

Answer

Dry gangrene

Answer

Gas gangrene

Answer

Fournier's gangrene

Question 8

What does Ghon's focus indicate in the context of tuberculosis?

Accepted Answer

Primary complex

Answer

Post primary tuberculosis

Answer

Miliary tuberculosis

Answer

Tuberculous lymphadenitis

Question 9

IgA nephropathy is not associated with which of the following?

Accepted Answer

Decreased complement level

Answer

Focal mesangial proliferation

Answer

Gross hematuria concurrent with upper respiratory infection

Answer

Immunofluorescence deposits contain IgA and IgG

Question 10

Lines of Zahn are LEAST likely to be seen in -

Accepted Answer

Lung

Answer

Liver

Answer

Kidney

Answer

Heart

NEET-PG 2015

Anatomy

Biochemistry

Forensic Medicine

Internal Medicine

Pathology