General Pathology Practice Questions

Q: What percentage of offspring will be affected by color blindness when a healthy male mates with a heterozygous female?

25%. **Explanation:** **1. Understanding the Concept:** Color blindness is an **X-linked recessive** disorder [1]. To determine the inheritance pattern, we use a Punnett square. * **Genotype of Healthy Male:** $XY$ * **Genotype of Heterozygous (Carrier) Female:** $X^cX$ (where $X^c$ carries the defective gene) **The Cross:** * **Daughter 1 ($XX$):** Healthy (Non-carrier) * **Daughter 2 ($X^cX$):** Healthy (Carrier) * **Son 1 ($XY$):** Healthy * **Son 2 ($X^cY$):** **Affected** [2] Out of the four possible offspring combinations, only one (the son inheriting the $X^c$ chromosome) is clinically affected. Therefore, **25% of the total offspring** will be affected. **2. Analysis of Incorrect Options:** * **A (0%):** Incorrect, as the mother is a carrier; there is a 50% chance her sons will be affected [2]. * **C (50%):** This would be the answer if the question asked for the percentage of **sons** affected, or if the father also had the disease. * **D (100%):** This only occurs if the father is affected and the mother is homozygous ($X^cX^c$). **3. NEET-PG Clinical Pearls:** * **Criss-cross Inheritance:** X-linked recessive traits are typically passed from an affected father to his grandsons through his carrier daughters [1]. * **Prevalence:** Color blindness is significantly more common in males (~8%) than females (~0.5%) because males only require one defective X chromosome to express the phenotype [1]. * **Common Types:** Protanopia (red-blind) and Deuteranopia (green-blind) are the most frequent. * **Testing:** **Ishihara charts** are the gold standard for screening red-green color blindness. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, p. 151. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, p. 179.

Q: Which of the following is a stain for fat cells?

Sudan IV. **Explanation:** **Correct Answer: C. Sudan IV** Sudan IV (and other Sudan dyes like Sudan Black B and Oil Red O) are **lipid-soluble stains** used to demonstrate neutral triglycerides and lipids in tissue sections [1]. The underlying principle is "physical solubility": the dye is more soluble in the lipid droplets than in the solvent (usually alcohol or propylene glycol), causing the fat cells to take up the pigment. *Note:* For lipid staining, **frozen sections** must be used because routine processing (paraffin embedding) involves alcohols and xylene, which dissolve lipids, leaving behind empty vacuoles [1]. **Incorrect Options:** * **A. PAS (Periodic Acid-Schiff):** Primarily used to demonstrate **glycogen**, mucopolysaccharides, and basement membranes. It stains these structures magenta/bright pink. * **B. Prussian Blue (Perl’s Stain):** A histochemical reaction used to detect **ferric iron** (hemosiderin). It is the gold standard for diagnosing conditions like hemochromatosis or sideroblastic anemia. * **C. Alcian Blue:** A stain used to identify **acid mucopolysaccharides** and mucins. It is frequently used to diagnose Barrett's esophagus (goblet cells) and certain connective tissue tumors. **High-Yield Clinical Pearls for NEET-PG:** * **Oil Red O** is the most commonly used stain for fat in current practice as it provides a more intense red color than Sudan IV [1]. * **Sudan Black B** is the most sensitive lipid stain and is also used in hematopathology to differentiate **AML (positive)** from ALL (negative). * **Osmium Tetroxide** is another method for staining fat, which turns lipids black and also acts as a fixative for electron microscopy. **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. 73-74.

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.

Question 1

What type of inheritance pattern is observed in MELAS syndrome?

Accepted Answer

Mitochondrial

Answer

Autosomal dominant

Answer

Autosomal recessive

Answer

X-linked

Question 2

Which of the following conditions shows the maximum deposits of lipofuscin?

Accepted Answer

Severe malnutrition

Answer

Gaucher's disease

Answer

Tay-Sachs disease

Answer

Acute enteric fever

Question 3

What percentage of offspring will be affected by color blindness when a healthy male mates with a heterozygous female?

Accepted Answer

25%

Answer

0%

Answer

50%

Answer

100%

Question 4

All of the following are features of wet gangrene except?

Accepted Answer

Line of demarcation

Answer

Spreads faster

Answer

Arterial and venous block

Answer

Not localized

Question 5

Which of the following is a stain for fat cells?

Accepted Answer

Sudan IV

Answer

PAS

Answer

Prussian blue

Answer

Alcian blue

Question 6

Laminated concretions of calcium and proteins are:

Accepted Answer

Schaumann's bodies

Answer

Ferruginous bodies

Answer

Asteroid bodies

Answer

Gamna-Gandy bodies

Question 7

Dystrophic calcification is seen in which of the following?

Accepted Answer

Dead tissue

Answer

Skin layers

Answer

Salivary glands

Answer

Normal tissues

Question 8

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 9

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

Accepted Answer

Haemophilia

Answer

Cystic fibrosis

Answer

Hereditary spherocytosis

Answer

Neurofibromatosis

Question 10

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

General Pathology — MCQs

General Pathology — MCQs

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