General Pathology Practice Questions

Q: Telomerase activity is expressed in which of the following cell types?

Germ cells. **Explanation:** **1. Why Germ Cells are Correct:** Telomerase is a specialized ribonucleoprotein enzyme (a reverse transcriptase) that adds TTAGGG repeats to the ends of chromosomes (telomeres). In most somatic cells, telomerase is absent; therefore, telomeres shorten with every cell division, eventually leading to replicative senescence (the Hayflick limit). However, **germ cells** (and stem cells) must maintain their telomere length to ensure that genetic information is passed intact to the next generation [1]. High telomerase activity in germ cells allows them to divide indefinitely without losing chromosomal integrity [1]. **2. Why Other Options are Incorrect:** * **Myocytes (A) and Osteocytes (C):** These are terminally differentiated, permanent, or stable cells. They lack telomerase activity. As they age or undergo limited repair, their telomeres shorten, contributing to cellular aging. * **Keratinocytes (B):** While basal epithelial cells (stem cells) have some telomerase activity, mature keratinocytes are differentiated somatic cells that eventually lose this activity as they move toward the stratum corneum and undergo programmed cell death. **3. High-Yield Clinical Pearls for NEET-PG:** * **Cancer Connection:** Approximately **85-90% of human cancer cells** upregulate telomerase [1]. This is a hallmark of "immortality" in malignancy, allowing tumor cells to bypass senescence [1]. * **Stem Cells:** Telomerase is present at low levels in somatic stem cells (e.g., hematopoietic stem cells) but is highest in germ cells [1]. * **Shelterin Complex:** This is a group of proteins that binds to telomeres to protect chromosome ends from being mistaken for double-stranded DNA breaks. * **Progeria (Hutchinson-Gilford Syndrome):** A condition of premature aging often linked to accelerated telomere attrition. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 311-312.

Q: Which is the most demineralised zone in enamel caries?

Body of lesion. **Explanation:** In the histopathology of enamel caries, the lesion is divided into four distinct zones based on the degree of demineralization and pore volume. These zones are identified using polarized light microscopy. **1. Body of Lesion (Correct Answer):** This is the largest portion of the incipient lesion and represents the **most demineralized zone**. It has a pore volume of **5% to 25%** (compared to <0.1% in normal enamel). Due to the significant loss of mineral content (apatite crystals), it appears the most radiolucent on radiographs and shows the greatest enhancement of striae of Retzius. **2. Why other options are incorrect:** * **Translucent Zone:** This is the advancing front of the lesion and the **first observable change**. It is the *least* demineralized zone, with a pore volume of only **1%**. * **Dark Zone:** Located between the translucent zone and the body of the lesion, it has a pore volume of **2% to 4%**. It appears "dark" because its tiny pores are filled with air or gas, which does not transmit light. It represents a zone of active reprecipitation. * **Surface Zone:** This is the relatively intact outer layer (approx. 40μm thick). It remains highly mineralized (pore volume **<1%**) due to the presence of fluoride and the constant remineralization from saliva, acting as a barrier until the lesion cavitates. **High-Yield Clinical Pearls for NEET-PG:** * **Sequence of zones (Deep to Superficial):** Translucent Zone → Dark Zone → Body of Lesion → Surface Zone. * **Pore Volume Gradient:** Translucent (1%) < Dark (2-4%) < Surface (<1% but functionally intact) < **Body (5-25%)**. * The **Dark Zone** is considered an indicator of the dynamics of the lesion; a wider dark zone often suggests a slower-progressing or arresting lesion.

Q: What is the defect in Marfan syndrome?

Fibrillin 1. **Explanation:** **Marfan Syndrome** is an autosomal dominant disorder of connective tissue caused by a mutation in the **FBN1 gene** located on chromosome **15q21**. 1. **Why Fibrillin-1 is correct:** The FBN1 gene encodes **Fibrillin-1**, a major glycoprotein component of extracellular microfibrils. These microfibrils serve as a scaffold for the deposition of elastin. In Marfan syndrome, the defect leads to mechanical instability of tissues and excessive activation of **TGF-β** (Transforming Growth Factor-beta), which normally binds to fibrillin [1]. Excess TGF-β causes deleterious effects on vascular smooth muscle and extracellular matrix integrity [1]. 2. **Why other options are incorrect:** * **Fibrillin-2:** Mutations in the *FBN2* gene (Chromosome 5) lead to **Congenital Contractural Arachnodactyly (Beals Syndrome)**. While it shares skeletal features with Marfan syndrome, it does not typically involve the aorta or eyes. * **Fibrillin-3 & 4:** These are less clinically significant in human pathology compared to Fibrillin-1 and 2 and are not associated with Marfan syndrome. **High-Yield Clinical Pearls for NEET-PG:** * **Skeletal:** Tall stature, arachnodactyly (long fingers), pectus excavatum, and high-arched palate [1]. * **Ocular:** **Ectopia lentis** (dislocation of the lens), typically **upward and outward** (superior-temporal). * **Cardiovascular (Most Serious):** Mitral valve prolapse (MVP) and **Cystic Medial Necrosis** of the aorta, leading to aortic aneurysm or dissection [1]. * **Diagnosis:** Based on the **Ghent Criteria**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 153-154.

Question 1

Klinefelter's syndrome is associated with which of the following?

Accepted Answer

XXY genotype

Answer

Male habitus

Answer

Infertility

Answer

Azoospermia

Question 2

Which of the following is an example of apoptosis?

Accepted Answer

Councilman bodies

Answer

Gamma Gandy bodies

Answer

Russell bodies

Answer

None of the above

Question 3

Apoptosis is induced by:

Accepted Answer

Activation of Caspases

Answer

Activation of Interleukins

Answer

Activation of MAP Kinase

Answer

Activation of Phospholipase C

Question 4

Telomerase activity is expressed in which of the following cell types?

Accepted Answer

Germ cells

Answer

Myocytes

Answer

Keratinocytes

Answer

Osteocytes

Question 5

What is the most common gene responsible for hereditary hemochromatosis?

Accepted Answer

HFE gene

Answer

HJV gene

Answer

HAMP gene

Answer

TfR2 gene

Question 6

Which is the most demineralised zone in enamel caries?

Accepted Answer

Body of lesion

Answer

Translucent zone

Answer

Dark zone

Answer

Surface zone

Question 7

Lipid peroxidation of polyunsaturated lipids of subcellular membranes produces which of the following?

Accepted Answer

Lipofuscin

Answer

Hemosiderin

Answer

Both lipofuscin and hemosiderin

Answer

None of the above

Question 8

Decrease in cell size refers to which of the following cellular adaptations?

Accepted Answer

Atrophy

Answer

Metaplasia

Answer

Hyperplasia

Answer

Hypertrophy

Question 9

A dermoid cyst is a form of:

Accepted Answer

Cystic teratoma

Answer

Cystic hamartoma

Answer

Choriostoma

Answer

Hamartoma

Question 10

What is the defect in Marfan syndrome?

Accepted Answer

Fibrillin 1

Answer

Fibrillin 2

Answer

Fibrillin 3

Answer

Fibrillin 4

General Pathology — MCQs

General Pathology — MCQs

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