General Pathology Practice Questions

Q: The retinoblastoma gene regulates which cell cycle phase transition?

G1-S phase. The **Retinoblastoma (RB) gene**, located on chromosome **13q14**, is a critical tumor suppressor gene that acts as the "governor" of the cell cycle [1]. ### Why G1-S phase is correct: The RB protein controls the **G1 to S phase transition**, which is the primary checkpoint for cell division [1]. * **Hypophosphorylated (Active) State:** In its active form, RB binds to and sequesters the **E2F transcription factor** [1]. This prevents the transcription of genes (like Cyclin E) required for the S-phase, effectively "braking" the cell cycle. * **Hyperphosphorylated (Inactive) State:** When the cell receives growth signals, Cyclin D-CDK4/6 complexes phosphorylate RB [1]. This causes RB to release E2F, allowing the cell to cross the **restriction point (R point)** and enter the S-phase. ### Why other options are incorrect: * **G2-M phase:** This transition is primarily regulated by **Cyclin B-CDK1** (Mitosis Promoting Factor) and DNA damage sensors like p53, not the RB protein [2]. * **G0-S phase:** Cells in G0 (quiescence) must first enter G1 before proceeding to S. RB specifically regulates the exit from G1 into S. * **S-G2 phase:** This transition involves ensuring DNA replication is complete; it is not the primary site of RB protein activity. ### NEET-PG High-Yield Pearls: * **Knudson’s "Two-Hit" Hypothesis:** Both alleles of the RB gene must be inactivated for tumor development [1]. * **Associated Tumors:** Mutations are linked to Retinoblastoma (familial and sporadic) and **Osteosarcoma**. * **Viral Interaction:** The **E7 protein** of High-risk HPV (16, 18) binds to and inactivates RB, leading to uncontrolled cell proliferation in cervical cancer [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 301-302. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 302-303.

Q: Quiescent cells belong to which phase of the cell cycle?

G0. **Explanation:** The cell cycle is divided into phases of growth and division. Cells are categorized into three groups based on their proliferative capacity: Labile, Stable (Quiescent), and Permanent cells [1]. **Why G0 is Correct:** **Quiescent cells** (Stable cells) are those that have exited the cell cycle and entered a state of dormancy known as the **G0 phase** [1]. In this phase, cells are metabolically active but are not actively dividing. However, they retain the capacity to re-enter the cell cycle (at the G1 phase) in response to specific stimuli, such as growth factors or tissue injury (e.g., hepatocytes after a partial hepatectomy) [1]. **Why other options are incorrect:** * **G1 (Gap 1):** This is the pre-synthetic phase where the cell prepares for DNA replication. Cells in G1 are committed to the cycle, unlike quiescent cells which are outside it [1]. * **S (Synthesis):** This is the phase where DNA replication occurs. * **M (Mitosis):** This is the phase of actual nuclear and cytoplasmic division. **High-Yield Clinical Pearls for NEET-PG:** 1. **Examples of Quiescent (Stable) Cells:** Hepatocytes, proximal renal tubular cells, and mesenchymal cells (fibroblasts, smooth muscle) [1]. 2. **Labile Cells:** These are always in the cell cycle (e.g., hematopoietic cells in bone marrow, surface epithelia of the GI tract and skin) [1]. 3. **Permanent Cells:** These have permanently exited the cell cycle and cannot undergo division (e.g., Neurons, Cardiac myocytes, Skeletal muscle) [1]. 4. **Restriction Point:** The transition from G1 to S is the most critical checkpoint in the cell cycle, regulated primarily by Cyclin D and CDK4/6 [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. With Illustrations By, pp. 37-38.

Q: A cyst arising from the rests of Malassez is:

Radicular cyst. **Explanation:** The **Radicular cyst** (also known as a Periapical cyst) is the most common inflammatory odontogenic cyst. It arises from the **epithelial rests of Malassez**, which are remnants of Hertwig’s epithelial root sheath (HERS) located in the periodontal ligament [1]. When a tooth becomes non-vital due to caries or trauma, the resulting inflammation (periapical granuloma) stimulates these dormant epithelial rests to proliferate, eventually leading to cyst formation [1]. **Analysis of Options:** * **Dentigerous Cyst:** This is a developmental cyst that originates from the **reduced enamel epithelium** (REE). It typically surrounds the crown of an unerupted tooth (most commonly the mandibular 3rd molar) and attaches at the cementoenamel junction. * **Dental Cyst:** This is a general, non-specific term often used interchangeably with radicular cysts in older literature, but in a competitive exam context, "Radicular cyst" is the precise pathological diagnosis for rests of Malassez origin. * **Keratocyst (Odontogenic Keratocyst/OKC):** This arises from the **dental lamina** (rests of Serres). It is known for its aggressive behavior, high recurrence rate, and association with Gorlin-Goltz syndrome. **NEET-PG High-Yield Pearls:** * **Rests of Malassez:** Associated with Radicular cysts (Inflammatory). * **Rests of Serres (Dental Lamina):** Associated with OKC and Ameloblastoma (Developmental/Neoplastic). * **Reduced Enamel Epithelium:** Associated with Dentigerous cysts. * **Rushton bodies:** Eosinophilic, linear, or curved structures found in the epithelial lining of radicular cysts (highly characteristic). * **Radiology:** Radicular cysts appear as well-defined unilocular radiolucencies at the apex of a **non-vital** tooth. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Head and Neck, pp. 741-742.

Question 1

Extracellular hyaline change is seen in:

Accepted Answer

Arteriosclerosis

Answer

Chronic glomerulonephritis

Answer

Leiomyoma

Answer

Alcoholic hyaline

Question 2

Which of the following is not a hereditary disease?

Accepted Answer

Cretinism

Answer

Neurofibromatosis

Answer

Huntington's disease

Answer

Hereditary spherocytosis

Question 3

All of the following events occur during mitosis except:

Accepted Answer

DNA replication

Answer

Cytokinesis

Answer

Chromatids separate

Answer

The kinetochore becomes evident

Question 4

Which HLA marker is associated with Behcet's syndrome?

Accepted Answer

HLA-B51

Answer

HLA-B27

Answer

HLA-DR5

Answer

HLA-CW6

Question 5

What is the primary purpose of sentinel lymph node biopsy in carcinoma of the breast?

Accepted Answer

Staging the tumors

Answer

Early diagnosis of cancer

Answer

Frozen section analysis

Answer

Detection of occult disease

Question 6

The retinoblastoma gene regulates which cell cycle phase transition?

Accepted Answer

G1-S phase

Answer

G2-M phase

Answer

G0-S phase

Answer

S-G2 phase

Question 7

Metastatic calcifications are typically seen in which of the following conditions?

Accepted Answer

Hypercalcemia

Answer

Hypoparathyroidism

Answer

Vitamin D deficiency

Answer

All the above

Question 8

Quiescent cells belong to which phase of the cell cycle?

Accepted Answer

G0

Answer

G1

Answer

M

Answer

S

Question 9

A cyst arising from the rests of Malassez is:

Accepted Answer

Radicular cyst

Answer

Dental cyst

Answer

Dentigerous cyst

Answer

Keratocyst

Question 10

S100 is a marker used in the diagnosis of which of the following conditions?

Accepted Answer

All of the above

Answer

Melanoma

Answer

Schwannoma

Answer

Langerhans cell histiocytosis (LCH)

General Pathology — MCQs

General Pathology — MCQs

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