NEET-PG 2012 Practice Questions

Q: During incision and drainage of ischiorectal abscess, which nerve is most likely to be injured?

Inferior rectal nerve. ***Inferior rectal nerve*** - The **inferior rectal nerve** innervates the **external anal sphincter** and the skin around the anus, making it vulnerable during an incision and drainage of an **ischiorectal abscess** due to its anatomical proximity. - Injury to this nerve can lead to **fecal incontinence** or altered sensation in the perianal region. *Superior rectal nerve* - The **superior rectal nerve** is primarily involved in the innervation of the **rectum** and is not directly located in the area of an **ischiorectal abscess**. - This nerve supplies the smooth muscle of the rectum and is not anatomically vulnerable during incision and drainage of an abscess in the ischiorectal fossa. *Superior gluteal nerve* - The **superior gluteal nerve** supplies the **gluteus medius**, **gluteus minimus**, and **tensor fasciae latae muscles**, which are typically located much more superior and lateral to an **ischiorectal abscess**. - Damage to this nerve causes a characteristic **Trendelenburg gait**, which is unrelated to perianal surgery. *Inferior gluteal nerve* - The **inferior gluteal nerve** innervates the **gluteus maximus muscle**, which is also located more superiorly and laterally relative to the **ischiorectal fossa**. - Injury to this nerve would primarily affect hip extension and is not a common complication of **ischiorectal abscess** drainage.

Q: Anaplerotic reaction is catalyzed by?

Pyruvate carboxylase. ***Pyruvate carboxylase*** - **Pyruvate carboxylase** catalyzes the ATP-dependent carboxylation of **pyruvate** to **oxaloacetate**. - This reaction is crucial for replenishing intermediates of the **citric acid cycle**, making it an anaplerotic reaction. *Enolase* - **Enolase** catalyzes the conversion of **2-phosphoglycerate** to **phosphoenolpyruvate** in **glycolysis**. - This reaction is part of catabolism and does not replenish citric acid cycle intermediates. *Pyruvate kinase* - **Pyruvate kinase** catalyzes the final step of **glycolysis**, converting **phosphoenolpyruvate** to **pyruvate**. - This enzyme is involved in ATP production and the overall catabolic pathway of glucose. *G6PD* - **Glucose-6-phosphate dehydrogenase (G6PD)** is the rate-limiting enzyme in the **pentose phosphate pathway**. - It produces **NADPH** and precursors for nucleotide synthesis, but not directly involved in anaplerotic reactions for the citric acid cycle.

Q: Which of the following is an ω-6 fatty acid?

Linoleic acid. ***Linoleic acid*** - **Linoleic acid** (LA), an 18-carbon fatty acid with two double bonds (18:2), is classified as an **ω-6 fatty acid** because its first double bond is located at the sixth carbon atom from the methyl end of the fatty acid chain. - It is an **essential fatty acid** that must be obtained through diet, serving as a precursor for other ω-6 fatty acids like arachidonic acid. *Cervonic acid* - **Cervonic acid** is another name for **docosahexaenoic acid (DHA)**, which is an **ω-3 fatty acid** (22:6). - Its first double bond is located at the third carbon from the methyl end. *Alpha linolenic acid* - **Alpha-linolenic acid** (ALA) is an **ω-3 fatty acid** (18:3). - Its first double bond is located at the third carbon atom from the methyl end. *Elaidic acid* - **Elaidic acid** is a **trans fatty acid** (18:1 trans-9). - It is classified as an **ω-9 fatty acid** due to the position of its double bond, but its trans configuration is the primary distinguishing feature.

Q: What is the primary metal ion found in myoglobin?

Iron. ***Iron*** - **Iron** is the central metal ion in the **heme group** of myoglobin. - It is responsible for **binding oxygen** reversibly, which is myoglobin's primary function in muscle tissue. *Copper* - **Copper** is a component of several enzymes, such as **cytochrome c oxidase** and **superoxide dismutase**, but not myoglobin. - It plays a role in **electron transport** and connective tissue formation. *Selenium* - **Selenium** is an essential trace element that functions as a component of **glutathione peroxidase**, an antioxidant enzyme. - It is not found in the structure of myoglobin. *Zinc* - **Zinc** is a critical component of many enzymes, including **carbonic anhydrase** and **DNA polymerase**. - It is involved in **immune function** and wound healing, but not in oxygen transport by myoglobin.

Q: What is the primary function of a primer in DNA replication?

Initiation of DNA replication. ***Initiation of DNA replication*** - DNA polymerase cannot synthesize new DNA strands de novo; it requires a pre-existing 3'-hydroxyl group to begin adding nucleotides. - The **primer**, a short RNA sequence, provides this necessary **3'-hydroxyl group**, allowing DNA polymerase to start synthesizing the new DNA strand. *Transcription* - This process involves synthesizing **RNA from a DNA template**, primarily carried out by **RNA polymerase**. - While primers are involved in DNA synthesis, they do not directly initiate the process of transcription. *Translation* - **Translation** is the process of synthesizing **proteins from mRNA templates** using ribosomes, tRNA, and amino acids. - This process is distinct from DNA synthesis and does not involve primers; its initiation involves start codons and ribosomal subunits. *Termination of DNA replication* - **Termination of DNA replication** occurs when replication forks meet or at specific termination sequences, often with the involvement of specialized proteins. - Primers are involved in the *start* of replication, not its conclusion.

Q: What is attached to the 3' end of mRNA after transcription?

Poly-A tail. ***Poly-A tail*** - A **poly-A tail**, consisting of multiple adenosine monophosphates, is added to the **3' end of mRNA** after transcription to protect it from degradation. - This modification aids in the **transport of mRNA from the nucleus to the cytoplasm** and in its translation. *CCA* - The **CCA sequence** is found at the **3' end of tRNA**, not mRNA, and is critical for amino acid attachment. - It is added post-transcriptionally to tRNA molecules by the enzyme **tRNA nucleotidyltransferase**. *Intron* - **Introns** are non-coding regions within a gene that are transcribed into mRNA but are subsequently removed during **RNA splicing**, not added to the 3' end. - Their removal ensures that only the **coding regions (exons)** are translated into protein. *7-methylguanosine* - **7-methylguanosine** forms the **5' cap** of mRNA, which is added to the 5' end, not the 3' end. - This cap is important for **mRNA stability**, ribosome binding, and protection against degradation.

Q: What is the chromosomal translocation associated with Acute Myeloid Leukemia M3?

t(15;17). ***T (15,17)*** [1][2][3] - This translocation pertains to **Acute Promyelocytic Leukemia (APL)**, associated with the fusion gene **PML-RARA** [1][3]. - APL is characterized by **promyelocytes** with heavy granulation and a clinical presentation that includes coagulopathy [2][3]. *T (8, 21)* - This translocation is associated with **AML M2**, involving the **RUNX1-RUNX1T1** fusion gene [3]. - It does not correlate with the classic features of AML M3, which is specifically characterized by T (15,17). *T (9,11)* - Primarily seen in **AML M5**, this translocation is not related to the pathophysiology of AML M3. - The fusion commonly observed here is **MLL-AFF1**, which affects different types of leukemias, not APL. *T (18,21)* - This translocation does not have a significant association with any specific type of acute myeloid leukemia. - Unlike T (15,17), it is not linked to the classic features or unique clinical presentation seen in AML M3. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, pp. 620-621. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, pp. 621-622. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, p. 620.

Q: Which acquired condition is most commonly associated with spherocytes?

Autoimmune hemolytic anemia (AIHA). ***Autoimmune haemolytic anemia*** - This condition is characterized by the **production of antibodies** against the patient's own red blood cells, leading to **destruction** and the formation of spherocytes [1]. - The presence of ***maximum spherocytes*** in blood smears is a hallmark of this disorder due to **extravascular hemolysis** [1]. *Aplastic anemia* - Aplastic anemia is mainly due to **failure of hematopoiesis**, resulting in pancytopenia rather than spherocyte formation. - It typically presents with **normocytic** or **macrocytic anemia**, not spherocytes, as the bone marrow is not producing enough red blood cells [2]. *Vit B12 deficiency* - Vit B12 deficiency usually causes **macrocytic anemia** characterized by **megaloblastic changes** in the bone marrow and peripheral blood, not the formation of spherocytes. - The primary indicators would be **hypersegmented neutrophils** and large, ovalocytes rather than spherocytes. *None* - This option incorrectly implies that no condition causes maximum spherocytes, while autoimmune hemolytic anemia is the known condition for this finding. - Spherocytes are a specific sign in hemolytic processes and are definitely seen in conditions like **autoimmune hemolytic anemia**. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 602-603. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 662-663.

Q: Which tumor marker is most commonly associated with lung and breast carcinoma?

CEA. ***CEA*** - **Carcinoembryonic antigen (CEA)** is a tumor marker commonly associated with **lung** and **breast cancers** [1]. - Elevated levels of CEA are often observed in **various malignancies**, making it useful for monitoring treatment response and recurrence. *CA-15-3* - While **CA-15-3** is a breast cancer marker, it is less specific than CEA and often used primarily for **monitoring** but not for initial diagnosis. - It is primarily elevated in **breast carcinoma**, not typically associated with **lung cancer**. *11CG* - This ppears to be incorrectly referenced and may not exist as a recognized tumor marker for lung or breast cancer. - There are no clinical associations with lung or breast cancer, making it irrelevant in this context. *AFP* - **Alpha-fetoprotein (AFP)** is primarily associated with **liver** and **germ cell tumors**, not commonly associated with lung or breast cancers [1]. - Elevated AFP levels do not correlate with lung or breast carcinomas, distinguishing it from CEA's relevance. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, p. 346.

Q: Which of the following components are included in microcirculation?

Capillaries, venules, and arterioles. ***Capillaries, venules, and arterioles*** - **Microcirculation** is the portion of the **circulatory system** that includes the **smallest blood vessels**, specifically the **arterioles**, **capillaries**, and **venules**. - These vessels are crucial for the **delivery of oxygen** and **nutrients** to tissues and the removal of waste products. *Capillaries* - While **capillaries** are a vital part of **microcirculation** and the primary site of nutrient and waste exchange, they alone do not encompass the entire microcirculatory unit. - The microcirculation also includes the vessels that feed into and drain from the capillaries: the **arterioles** and **venules**. *Aorta* - The **aorta** is the **largest artery** in the body, part of the **macrocirculation**, which distributes blood from the heart to the systemic circulation. - It is not considered part of the **microcirculation** due to its large size and primary function as a high-pressure conduit rather than a site of exchange. *Arteries and veins* - **Arteries** and **veins** are primarily components of the **macrocirculation**, responsible for transporting blood to and from the systemic and pulmonary circuits. - While arterioles and venules (small arteries and veins) are part of the microcirculation, the broader terms "arteries" and "veins" typically refer to the larger vessels and do not exclusively define the microcirculatory network.

Question 1

During incision and drainage of ischiorectal abscess, which nerve is most likely to be injured?

Accepted Answer

Inferior rectal nerve

Answer

Superior rectal nerve

Answer

Superior gluteal nerve

Answer

Inferior gluteal nerve

Question 2

Anaplerotic reaction is catalyzed by?

Accepted Answer

Pyruvate carboxylase

Answer

Enolase

Answer

Pyruvate kinase

Answer

G6PD

Question 3

Which of the following is an ω-6 fatty acid?

Accepted Answer

Linoleic acid

Answer

Cervonic acid

Answer

Alpha linolenic acid

Answer

Elaidic acid

Question 4

What is the primary metal ion found in myoglobin?

Accepted Answer

Iron

Answer

Copper

Answer

Selenium

Answer

Zinc

Question 5

What is the primary function of a primer in DNA replication?

Accepted Answer

Initiation of DNA replication

Answer

Transcription

Answer

Translation

Answer

Termination of DNA replication

Question 6

What is attached to the 3' end of mRNA after transcription?

Accepted Answer

Poly-A tail

Answer

CCA

Answer

Intron

Answer

7-methylguanosine

Question 7

What is the chromosomal translocation associated with Acute Myeloid Leukemia M3?

Accepted Answer

t(15;17)

Answer

t(18;21)

Answer

t(9;11)

Answer

t(8;21)

Question 8

Which acquired condition is most commonly associated with spherocytes?

Accepted Answer

Autoimmune hemolytic anemia (AIHA)

Answer

Vitamin B12 deficiency anemia

Answer

Aplastic anemia

Answer

None of the options

Question 9

Which tumor marker is most commonly associated with lung and breast carcinoma?

Accepted Answer

CEA

Answer

hCG

Answer

AFP

Answer

CA-15-3

Question 10

Which of the following components are included in microcirculation?

Accepted Answer

Capillaries, venules, and arterioles

Answer

Capillaries

Answer

Aorta

Answer

Arteries and veins

NEET-PG 2012

Anatomy

Biochemistry

Pathology

Physiology