General Pathology Practice Questions

Q: Which of the following is NOT a theory of the mechanism of aging?

Lysosomal degeneration theory. **Explanation:** Aging is a complex, progressive process characterized by the accumulation of cellular damage over time. The correct answer is **D (Lysosomal degeneration theory)** because it is not a recognized standalone theory of aging. In fact, cellular aging is often associated with a *decrease* in lysosomal efficiency (leading to the accumulation of lipofuscin) rather than the degeneration of the organelle itself as a primary cause. **Analysis of Options:** * **A. Free Radical Theory (Harman’s Theory):** One of the most widely accepted theories. it states that aging results from cumulative oxidative damage to cell components (lipids, proteins, DNA) caused by Reactive Oxygen Species (ROS) generated during mitochondrial respiration. * **B. Crosslinking of Collagen Theory:** This suggests that with age, proteins like collagen and elastin become increasingly cross-linked (often via glycation), making tissues stiffer and less functional. This explains the loss of elasticity in skin and blood vessels. * **C. Telomere Shortening Theory:** Known as the **Hayflick Limit**. Each cell division leads to the shortening of telomeres (protective DNA caps). Once telomeres reach a critical length, the cell enters senescence and stops dividing. **High-Yield Clinical Pearls for NEET-PG:** * **Lipofuscin:** Known as the "wear-and-tear" or "aging pigment," it is a product of incomplete lysosomal digestion of lipid-containing membranes. * **Progeria (Hutchinson-Gilford Syndrome):** A rare genetic condition of accelerated aging caused by a mutation in the *LMNA* gene, leading to the accumulation of **Progerin**. * **Werner Syndrome:** Often called "adult progeria," it is caused by a mutation in the *WRN* gene (DNA helicase), leading to defective DNA repair and rapid telomere shortening. * **Sirtuins:** A family of proteins (SIRT1-7) that are linked to longevity by promoting DNA repair and metabolic efficiency.

Q: Which of the following is an X-linked recessive (XLR) condition?

Haemophilia. **Explanation:** **Haemophilia (Option B)** is the correct answer. It is a classic example of an **X-linked recessive (XLR)** disorder [1]. In XLR conditions, the mutated gene is located on the X chromosome. Since males (XY) have only one X chromosome, a single mutated copy causes the disease. Females (XX) are typically asymptomatic carriers unless they have two mutated copies. Haemophilia A (Factor VIII deficiency) and Haemophilia B (Factor IX deficiency) both follow this inheritance pattern [1], leading to characteristic bleeding into joints (hemarthrosis) and muscles. **Why the other options are incorrect:** * **Cystic Fibrosis (Option A):** This is an **Autosomal Recessive (AR)** disorder caused by a mutation in the CFTR gene on chromosome 7. It requires two copies of the defective gene for phenotypic expression. * **Hereditary Spherocytosis (Option C):** This is primarily an **Autosomal Dominant (AD)** condition (in 75% of cases) involving defects in red blood cell membrane proteins like ankyrin or spectrin. * **Neurofibromatosis (Option D):** Both NF1 (chromosome 17) and NF2 (chromosome 22) are **Autosomal Dominant (AD)** disorders characterized by high penetrance and variable expressivity. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for XLR:** "**O**blivious **F**emale **G**ives **H**er **C**hild **D**isease" (**O**cular albinism, **F**abry disease, **G**6PD deficiency, **H**unter syndrome/Haemophilia, **C**hronic granulomatous disease, **D**uchenne muscular dystrophy). * **Rule of Thumb:** XLR disorders never show male-to-male transmission (fathers give their Y to sons). * **Lyonization:** In females, one X chromosome is randomly inactivated (Barr body), which can occasionally lead to "manifesting carriers" in XLR conditions.

Q: Which of the following patterns is seen in DNA electrophoresis?

Apoptosis. **Explanation:** The correct answer is **Apoptosis**. The hallmark of apoptosis on DNA electrophoresis is a characteristic **"Step-ladder pattern."** **1. Why Apoptosis is correct:** During apoptosis, specific calcium- and magnesium-dependent endonucleases (caspase-activated DNase) cleave the DNA at internucleosomal linker regions [1]. Since DNA is wrapped around histones in regular intervals of approximately 180–200 base pairs, this enzymatic cleavage results in DNA fragments of varying lengths that are multiples of 180–200 bp. When these fragments are separated by electrophoresis, they form a distinct "step-ladder" appearance. **2. Why the other options are incorrect:** * **Necrosis:** Unlike the programmed cleavage in apoptosis, necrosis involves random, uncontrolled degradation of DNA and the nucleus (karyolysis). This results in a diffuse, continuous distribution of DNA fragments of all sizes, appearing as a **"Smear pattern"** on electrophoresis. * **Dysplasia and Metaplasia:** These are cellular adaptations or pre-neoplastic changes involving alterations in cell size, shape, organization, or phenotype. They do not involve the specific DNA fragmentation patterns seen in programmed cell death [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Apoptosis:** Step-ladder pattern (Internucleosomal cleavage). * **Necrosis:** Smear pattern (Random cleavage). * **Gold Standard for Apoptosis:** The **TUNEL assay** (Terminal deoxynucleotidyl transferase dUTP nick end labeling) is used to detect these DNA fragments in situ. * **Annexin V:** A marker used to detect phosphatidylserine on the outer leaflet of the plasma membrane, another early marker of apoptosis [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Cellular Responses to Stress and Toxic Insults: Adaptation, Injury, and Death, pp. 63-65.

Question 1

Which of the following is NOT a theory of the mechanism of aging?

Accepted Answer

Lysosomal degeneration theory

Answer

Free radical theory

Answer

Crosslinking of collagen theory

Answer

Telomere shortening theory

Question 2

Which of the following is an X-linked recessive (XLR) condition?

Accepted Answer

Haemophilia

Answer

Cystic fibrosis

Answer

Hereditary spherocytosis

Answer

Neurofibromatosis

Question 3

Which of the following statements is false regarding apoptosis?

Accepted Answer

It is always pathological

Answer

Cell size is shrunken

Answer

Plasma membrane remains intact

Answer

Does not elicit inflammation

Question 4

Which of the following patterns is seen in DNA electrophoresis?

Accepted Answer

Apoptosis

Answer

Necrosis

Answer

Dysplasia

Answer

Metaplasia

Question 5

Which histopathological type of odontogenic keratocyst is commoner, more invasive, and has a greater tendency for recurrence?

Accepted Answer

Parakeratinised

Answer

Orthokeratinised

Answer

Non-keratinised

Answer

Diskeratinised

Question 6

Caseous necrosis is seen in which type of infection?

Accepted Answer

Treponemal infection

Answer

Cytomegalovirus (CMV) infection

Answer

Staphylococcal infection

Answer

Herpes Simplex Virus (HSV) infection

Question 7

All of the following are viral inclusion bodies, EXCEPT:

Accepted Answer

Psammoma bodies

Answer

Molluscum

Answer

Negri bodies

Answer

Bollinger bodies

Question 8

Which of the following is NOT an endogenous chemoattractant?

Accepted Answer

Integrins

Answer

C5a

Answer

LTB4

Answer

IL 8

Question 9

Which of the following is NOT responsible for the generation of Reactive Oxygen Species during Ischemia-Reperfusion Injury?

Accepted Answer

Activation of the complement system

Answer

Incomplete redox reactions by damaged mitochondria

Answer

Compromised cellular antioxidant defense mechanisms

Answer

Infiltrating leukocytes

Question 10

Myositis ossificans is an example of which of the following cellular adaptations?

Accepted Answer

Metaplasia

Answer

Hypertrophy

Answer

Hyperplasia

Answer

Both hyperplasia and hypertrophy

General Pathology — MCQs

General Pathology — MCQs

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