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.

Question 1

A 90-year-old woman with mild diabetes and Alzheimer's disease dies in her sleep. At autopsy, hepatocytes are noted to contain golden cytoplasmic granules that do not stain with Prussian blue. Which of the following best accounts for pigment accumulation in the liver of this patient?

Accepted Answer

Advanced age

Answer

Alzheimer disease

Answer

Congestive heart failure

Answer

Diabetic ketoacidosis

Question 2

All of the following trigger the intrinsic pathway of programmed cell death, except?

Accepted Answer

Activation of Fas receptor by FasL

Answer

Withdrawal of growth factor stimulus

Answer

Radiation injury

Answer

Intracellular protein misfolding

Question 3

Which of the following stains is NOT used for the detection of fat?

Accepted Answer

Congo red

Answer

Oil red O

Answer

Sudan black B

Answer

Sudan III

Question 4

What type of inheritance pattern is observed in MELAS syndrome?

Accepted Answer

Mitochondrial

Answer

Autosomal dominant

Answer

Autosomal recessive

Answer

X-linked

Question 5

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 6

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 7

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 8

Which of the following is a stain for fat cells?

Accepted Answer

Sudan IV

Answer

PAS

Answer

Prussian blue

Answer

Alcian blue

Question 9

Laminated concretions of calcium and proteins are:

Accepted Answer

Schaumann's bodies

Answer

Ferruginous bodies

Answer

Asteroid bodies

Answer

Gamna-Gandy bodies

Question 10

Dystrophic calcification is seen in which of the following?

Accepted Answer

Dead tissue

Answer

Skin layers

Answer

Salivary glands

Answer

Normal tissues

General Pathology — MCQs

General Pathology — MCQs

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