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 true for Klinefelter's syndrome?

Tall stature. **Explanation:** **Klinefelter Syndrome (47, XXY)** is the most common cause of male hypogonadism and occurs due to meiotic non-disjunction of sex chromosomes. 1. **Why "Tall Stature" is correct:** Patients with Klinefelter syndrome possess an extra X chromosome. The **SHOX gene** (Short Stature Homeobox gene), located on the distal short arms of the X and Y chromosomes, remains active. An extra copy of the SHOX gene leads to increased skeletal growth, resulting in **tall stature** and elongated lower limbs (eunuchoid body habitus) [1]. 2. **Why the other options are incorrect:** * **Option A (45, XO):** This is the karyotype for **Turner Syndrome**, which presents in females with short stature and streak ovaries [1]. * **Option C (Normal IQ):** While many patients have near-normal intelligence, there is a statistically significant association with **mild intellectual disability** or learning disabilities (specifically verbal lag). The degree of impairment often increases with the number of extra X chromosomes (e.g., 48, XXXY). * **Option D (Normal testes):** This is incorrect. The hallmark of Klinefelter is **testicular dysgenesis**. Patients present with small, firm testes, hyalinization of seminiferous tubules, and Leydig cell hyperplasia. **High-Yield Clinical Pearls for NEET-PG:** * **Karyotype:** Most commonly 47, XXY. * **Hormonal Profile:** Low Testosterone, **High FSH and LH** (Hypergonadotropic hypogonadism), and increased Estradiol. * **Clinical Features:** Gynecomastia (increased risk of male breast cancer), infertility (azoospermia), and reduced secondary male sexual characteristics. * **Barr Body:** Positive (due to the extra X chromosome). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 173-174.

Q: An apical cyst that has a direct connection with the apical foramen is termed as what?

Bay. **Explanation:** The question refers to the classification of periapical cysts based on their relationship with the root canal system. **1. Why "Bay" is correct:** A **Bay Cyst** (also known as a **Pocket Cyst**) is a specific histological variant of a radicular cyst. It is characterized by a lumen that is open to and continuous with the infected root canal through the apical foramen. Unlike a true cyst (which is a completely enclosed epithelial-lined cavity), a bay cyst is shaped like a "pouch" or "bay" attached to the root tip. Clinically, these are significant because they often heal following conventional root canal treatment (nonsurgical) once the source of infection in the canal is removed. **2. Why other options are incorrect:** * **Residual Cyst:** This is a radicular cyst that remains in the jaw after the offending tooth has been extracted. It is no longer connected to a tooth. * **Paradental Cyst:** These occur on the lateral aspect of the root, typically associated with partially erupted mandibular third molars and a history of pericoronitis. * **Collateral Cyst:** This is not a standard term in apical pathology. It may be confused with a Lateral Periodontal Cyst, which occurs on the lateral root surface but is developmental, not inflammatory. **High-Yield Facts for NEET-PG:** * **True Cyst vs. Bay Cyst:** A "True Cyst" is a self-sustaining, enclosed cavity not connected to the canal; it often requires surgical intervention (apicoectomy). A "Bay Cyst" is connected to the canal and usually resolves with RCT. * **Pathogenesis:** Both arise from the **Rests of Malassez** due to inflammatory stimulation. * **Radiology:** It is impossible to definitively differentiate a True Cyst from a Bay Cyst or a Periapical Granuloma on a standard radiograph alone.

Q: Which one of the following is NOT used as a tumor marker in testicular tumors?

CEA. **Explanation:** In the context of testicular germ cell tumors (GCTs), tumor markers are essential for diagnosis, staging, prognosis, and monitoring treatment response. **CEA (Carcinoembryonic Antigen)** is the correct answer because it is primarily a marker for gastrointestinal malignancies (like colorectal cancer) and is **not** used in the management of testicular tumors. **Analysis of Options:** * **AFP (Alpha-Fetoprotein):** This is a crucial marker for **Yolk Sac Tumors** [1]. It is also elevated in mixed germ cell tumors containing yolk sac elements. Importantly, AFP is *never* elevated in pure Seminomas. * **HCG (Human Chorionic Gonadotropin):** This is the hallmark marker for **Choriocarcinoma** (where levels are very high) [1]. It can also be mildly elevated in about 15-25% of pure Seminomas containing syncytiotrophoblastic giant cells [1]. * **LDH (Lactate Dehydrogenase):** While less specific than AFP or HCG, LDH correlates with the **tumor burden**, growth rate, and degree of tissue proliferation. It is used in the TNM staging (S category) of testicular tumors. **High-Yield Clinical Pearls for NEET-PG:** * **Pure Seminoma:** AFP is always **negative**. If AFP is elevated, the diagnosis must be revised to a Non-Seminomatous Germ Cell Tumor (NSGCT). * **Most sensitive marker for GCTs:** HCG. * **Marker for Teratoma:** No specific serum marker, though mixed tumors may show elevations based on other components [1]. * **Placental Alkaline Phosphatase (PLAP):** A highly specific tissue marker for Seminoma (seen on immunohistochemistry) [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lower Urinary Tract and Male Genital System, pp. 979-983.

Question 1

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 2

Which one of the following are the most important antigen-presenting cells in humans?

Accepted Answer

Langerhan's cells/histiocytes

Answer

Macrophages

Answer

Plasma cells

Answer

Lymphocytes

Question 3

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 4

Which of the following is true for Klinefelter's syndrome?

Accepted Answer

Tall stature

Answer

45, XO

Answer

Normal Intelligence Quotient

Answer

Normal testes and genitalia

Question 5

An apical cyst that has a direct connection with the apical foramen is termed as what?

Accepted Answer

Bay

Answer

Residual

Answer

Paradental

Answer

Collateral

Question 6

Insulin non-dependent diabetes mellitus correlates with which fat reserve?

Accepted Answer

Intra-abdominal fat

Answer

Lower body fat

Answer

Subcutaneous fat

Answer

Upper body fat

Question 7

Laminated concretions of calcium and proteins are:

Accepted Answer

Schaumann's bodies

Answer

Ferruginous bodies

Answer

Asteroid bodies

Answer

Gamna-Gandy bodies

Question 8

Which one of the following is NOT used as a tumor marker in testicular tumors?

Accepted Answer

CEA

Answer

AFP

Answer

LDH

Answer

HCG

Question 9

Dystrophic calcification is seen in which of the following?

Accepted Answer

Dead tissue

Answer

Skin layers

Answer

Salivary glands

Answer

Normal tissues

Question 10

A sample to look for uric acid crystals (gouty tophus) would be submitted to the pathology laboratory in:

Accepted Answer

Alcohol

Answer

Formalin

Answer

Distilled water

Answer

Normal saline

General Pathology — MCQs

General Pathology — MCQs

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