General Pathology Practice Questions

Q: Isoprostanes are formed from archidonic acid by which mechanism?

Non-enzymatic free radical peroxidation. **Explanation:** **Isoprostanes** are prostaglandin-like compounds that serve as highly sensitive and specific biomarkers of **oxidative stress**. **1. Why Option D is Correct:** Unlike prostaglandins, which are synthesized via enzymatic pathways, isoprostanes are formed by the **non-enzymatic, free radical-induced peroxidation** of arachidonic acid (and other polyunsaturated fatty acids) while they are still attached to membrane phospholipids. They are subsequently released by phospholipases and can be detected in plasma and urine. Because their formation is independent of enzymes and directly proportional to free radical activity, they are considered the "gold standard" for measuring lipid peroxidation in vivo. **2. Why Other Options are Incorrect:** * **Option A (Cyclooxygenase):** COX-1 and COX-2 enzymes are responsible for the enzymatic conversion of arachidonic acid into prostaglandins (PGE2, PGD2, etc.) and thromboxanes [1]. * **Option B (Lipooxygenase):** LOX enzymes (e.g., 5-LOX) convert arachidonic acid into leukotrienes and lipoxins [1]. * **Option C (Epoxide hydrolase):** This enzyme is involved in the metabolism of epoxides (like EETs) into diols; it is not involved in the primary peroxidation of arachidonic acid. **3. NEET-PG High-Yield Pearls:** * **Biomarker Status:** Isoprostanes (specifically **8-iso-PGF2α**) are the most reliable markers of oxidative stress in diseases like atherosclerosis, diabetes, and Alzheimer’s. * **Vasoactivity:** Unlike some prostaglandins, isoprostanes are potent **vasoconstrictors** (especially in renal and pulmonary vasculature). * **Membrane Damage:** Their formation is a hallmark of **irreversible cell injury** caused by reactive oxygen species (ROS). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 95.

Question 1

Which of the following factors prevents apoptosis in memory B cells?

Accepted Answer

Nerve growth factor (NGF)

Answer

Platelet-derived growth factor (PDGF)

Answer

Insulin-like growth factor (IGF)

Answer

Fibroblast growth factor (FGF)

Question 2

Histamine causes all the following except:

Accepted Answer

Platelet aggregation

Answer

Arteriolar dilatation

Answer

Increased permeability of venules

Answer

Constriction of large arteries

Question 3

All of the following are true about blood transfusion protocols EXCEPT:

Accepted Answer

Blood transfusions should commence within 60 minutes of removing the blood bag from refrigeration.

Answer

Whole blood or packed red blood cells must be transfused within 4 hours.

Answer

Transfusion sets should include a standard filter of 170 micrometers.

Answer

The usual needle size for blood transfusion is 18-19 gauge.

Question 4

Which of the following is a classical example of transplacental carcinogenesis?

Accepted Answer

Clear cell adenocarcinoma of vagina

Answer

Teratoma

Answer

Primary squamous cell carcinoma of vagina

Answer

Sarcoma botryoids

Question 5

Thrombomodulin-thrombin complex produces its anticoagulant effect by?

Accepted Answer

Inactivating factors V and VIII

Answer

Inactivating protein C

Answer

Inactivating protein S

Answer

Inactivating factor VIII

Question 6

Isoprostanes are formed from archidonic acid by which mechanism?

Accepted Answer

Non-enzymatic free radical peroxidation

Answer

Cyclooxygenase

Answer

Lipooxygenase

Answer

Epoxide hydrolase

Question 7

Mitochondrial abnormality is seen in which of the following conditions?

Accepted Answer

Oncocytoma

Answer

Krabbe's disease

Answer

Fabry disease

Answer

Fanconi syndrome

Question 8

What is the most common cause of cell injury?

Accepted Answer

Hypoxia

Answer

Ischemia

Answer

Carbon monoxide poisoning

Answer

Anemia

Question 9

Fat necrosis is not associated with which of the following procedures or conditions?

Accepted Answer

Carcinoma of the breast

Answer

Liposuction

Answer

Mammoplasty

Answer

Trauma

Question 10

Which of the following statements about the P53 gene is incorrect?

Accepted Answer

The wild-type, non-mutated form is associated with an increased risk of childhood tumors.

Answer

It can arrest the cell cycle at the G1 phase.

Answer

Its product is a 53 kDa protein.

Answer

It is located on chromosome 17.

General Pathology — MCQs

General Pathology — MCQs

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