General Pathology Practice Questions

Q: Tuberculosis infection is caused by the deletion of which of the following genes?

ATG5. **Explanation:** The correct answer is **ATG5**. **1. Why ATG5 is correct:** The **ATG5 (Autophagy-related 5)** gene is a critical component of the **autophagy** pathway. Autophagy is a cellular defense mechanism where the host cell (macrophage) sequesters intracellular pathogens like *Mycobacterium tuberculosis* (Mtb) into autophagosomes for degradation. * **Mechanism:** ATG5 is essential for the formation of the autophagosomal membrane. * **Clinical Significance:** Research has shown that the deletion or deficiency of ATG5 in macrophages leads to an inability to control Mtb replication, resulting in severe inflammation, high bacterial load, and increased susceptibility to tuberculosis. This highlights autophagy as a key innate immune response against Mtb. **2. Why the other options are incorrect:** * **BCL-2:** This is an **anti-apoptotic** gene. While it regulates programmed cell death, its primary clinical association is with follicular lymphoma (t14;18 translocation), not the direct susceptibility to TB infection. * **PTEN:** A tumor suppressor gene that inhibits the PI3K/AKT/mTOR pathway. Deletion is associated with various cancers (e.g., Cowden syndrome) rather than TB infection. * **P-53:** Known as the "Guardian of the Genome," it is a tumor suppressor gene involved in DNA repair and apoptosis. Mutations are linked to Li-Fraumeni syndrome and most human cancers. **High-Yield Clinical Pearls for NEET-PG:** * **Autophagy & TB:** *Mycobacterium tuberculosis* survives by inhibiting phagosome-lysosome fusion. Autophagy (driven by ATG5) can bypass this block to kill the bacteria. * **Vitamin D Link:** Vitamin D stimulates the expression of **Cathelicidin**, which further induces autophagy to fight TB. * **IFN-gamma:** This cytokine activates macrophages to induce autophagy, reinforcing the link between cell-mediated immunity and the ATG gene family.

Q: What fixative is used for bone histopathology?

10% formalin. **Explanation:** The primary goal of fixation in histopathology is to preserve biological tissues from decay (autolysis and putrefaction) while maintaining the structural integrity of cells and extracellular matrix. **Why 10% Formalin is Correct:** 10% Neutral Buffered Formalin (NBF) is the standard "universal fixative" used for most tissues, including bone. It works by forming cross-links between proteins (specifically methylene bridges), which stabilizes the tissue architecture. For bone histopathology, fixation in formalin is a mandatory first step before the specimen undergoes **decalcification** (the removal of calcium salts using acids like EDTA or Nitric acid) to allow for thin sectioning [1]. **Why Incorrect Options are Wrong:** * **Normal Saline:** This is an isotonic solution, not a fixative. It is used for temporary transport of fresh tissue (e.g., for immunofluorescence or frozen sections) but does not prevent autolysis. * **Rectified Spirit (Alcohol):** While alcohol is a fixative, it causes significant tissue shrinkage and hardening. It is primarily used for cytology smears or as a secondary fixative, but not as the primary choice for bone. * **Nothing:** Leaving tissue "dry" leads to rapid enzymatic degradation (autolysis) and bacterial growth, rendering the sample non-diagnostic. **High-Yield Clinical Pearls for NEET-PG:** * **Fixative of choice for Electron Microscopy:** Glutaraldehyde. * **Fixative for Testicular Biopsy:** Bouin’s solution (preserves nuclear detail). * **Fixative for Lipids/Fats:** Osmium tetroxide (also used in EM). * **Decalcifying agent of choice:** EDTA (chelating agent) is preferred for preserving enzyme morphology, though 5-10% Nitric acid is faster. * **Ideal ratio:** The volume of fixative should be **10 to 20 times** the volume of the tissue specimen.

Question 1

Tuberculosis infection is caused by the deletion of which of the following genes?

Accepted Answer

ATG5

Answer

BCL-2

Answer

PTEN

Answer

P-53

Question 2

Metastatic calcification of the gastrointestinal tract commonly affects the mucosa of:

Accepted Answer

Stomach

Answer

Esophagus

Answer

Ileum

Answer

Rectum

Question 3

During lactation, what change do uterine smooth muscles undergo?

Accepted Answer

Involution

Answer

Hyperplasia

Answer

Hypertrophy

Answer

Atrophy

Question 4

What fixative is used for bone histopathology?

Accepted Answer

10% formalin

Answer

Normal saline

Answer

Rectified spirit

Answer

Nothing

Question 5

Which organ is least resistant to oxygen depletion?

Accepted Answer

Heart

Answer

Liver

Answer

Kidney

Answer

Spleen

Question 6

Which stain is used for tissue fats?

Accepted Answer

Sudan IV

Answer

PAS

Answer

Prussian blue

Answer

Alcian blue

Question 7

A 25-year-old woman died shortly after childbirth. Autopsy revealed the presence of hair, fat, and epithelial cells within the pulmonary vessels. What is the probable cause of death?

Accepted Answer

Amniotic fluid embolism

Answer

Fat embolism

Answer

Disseminated intravascular coagulation (DIC)

Answer

Pulmonary thromboembolism

Question 8

Lipofuscin, the golden yellow pigment, is seen in heart muscles in which of the following conditions?

Accepted Answer

Atrophy

Answer

Hypertrophy

Answer

Infarction

Answer

Hyperplasia

Question 9

All of the following are included in the pathogenesis of edema except?

Accepted Answer

Decreased hydrostatic pressure of capillaries

Answer

Decreased plasma osmotic pressure of capillaries

Answer

Lymphatic obstruction

Answer

Increased vascular permeability

Question 10

Fibrinoid necrosis is seen in all EXCEPT-

Accepted Answer

Sarcoidosis

Answer

Polyarteritis nodosa

Answer

Systemic Lupus Erythematosus

Answer

Hepatitis B Virus infection

General Pathology — MCQs

General Pathology — MCQs

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