General Pathology Practice Questions

Q: What substance is commonly used for tissue preservation?

Formalin. **Explanation:** **1. Why Formalin is the Correct Answer:** Formalin (specifically **10% Neutral Buffered Formalin**) is the gold standard fixative used in histopathology. It works by creating **cross-links between proteins** (forming methylene bridges), which terminates biochemical reactions, prevents autolysis (self-digestion by enzymes), and inhibits putrefaction (bacterial decay). This preserves the tissue architecture in a state as close to life as possible, allowing for thin sectioning and staining. **2. Analysis of Incorrect Options:** * **Ethyl Alcohol:** While used as a fixative for cytology smears (e.g., Pap smears), it is a dehydrating agent. Using it for primary tissue preservation causes significant tissue shrinkage and hardening, making it unsuitable for routine surgical pathology. * **Sodium Chloride / Normal Saline:** These are isotonic solutions, not fixatives. They can keep tissue moist for a very short duration (e.g., during transport for a frozen section), but they do not stop autolysis. Prolonged exposure leads to tissue maceration and cellular degradation. **3. NEET-PG High-Yield Clinical Pearls:** * **Composition:** 10% Formalin is actually a 4% solution of Formaldehyde gas in water. * **Rate of Penetration:** Formalin penetrates tissue at a rate of approximately **1 mm per hour**. * **Glutaraldehyde:** This is the fixative of choice for **Electron Microscopy** as it preserves ultrastructural details better than formalin. * **Carnoy’s Fixative:** A rapid fixative containing alcohol, chloroform, and acetic acid; often used for preserving nucleic acids or identifying glycogen. * **Zenker’s Fluid:** Contains mercuric chloride; historically used for bone marrow biopsies to provide sharp nuclear detail.

Question 1

The ladder pattern observed in DNA electrophoresis during apoptosis is caused by the action of which enzyme?

Accepted Answer

Endonuclease

Answer

Transglutaminase

Answer

DNAse

Answer

Caspase

Question 2

Which chromosome is involved in Down's Syndrome?

Accepted Answer

21

Answer

22

Answer

13

Answer

X chromosome

Question 3

Which of the following conditions is not X-linked recessive?

Accepted Answer

Spinal muscular atrophy

Answer

Fragile X syndrome

Answer

Duchenne muscular dystrophy

Answer

Diabetes insipidus

Question 4

Maximum damage to DNA is caused by which type of radiation?

Accepted Answer

alpha rays

Answer

beta rays

Answer

gamma rays

Answer

X-rays and UV rays

Question 5

What substance is commonly used for tissue preservation?

Accepted Answer

Formalin

Answer

Ethyl alcohol

Answer

Sodium Chloride

Answer

Normal Saline

Question 6

Which of the following is NOT an integrin ligand?

Accepted Answer

CD 34

Answer

CD 54

Answer

CD 102

Answer

CD 106

Question 7

All of the following statements are true for cell aging except?

Accepted Answer

Enlargement of telomere

Answer

Decrease in the number of mitochondria

Answer

Glycosylation of DNA

Answer

Glycosylation of RNA

Question 8

Which type of immune cells are primarily responsible for recognizing and killing cancer cells?

Accepted Answer

NK cells

Answer

Basophils

Answer

Eosinophils

Answer

Neutrophils

Question 9

In apoptosis, Apaf-1 is activated by the release of which of the following substances from the mitochondria?

Accepted Answer

Cytochrome C

Answer

Bcl-2

Answer

Bax

Answer

Bcl-XL

Question 10

Which of the following surface glycoproteins is most often expressed in human hematopoietic stem cells?

Accepted Answer

CD 34

Answer

CD 22

Answer

CD 40

Answer

CD 15

General Pathology — MCQs

General Pathology — MCQs

On this page

Practice by Chapter

Want unlimited practice?