NEET-PG 2012 Practice Questions

Q: From which ribs does the spleen extend?

9th to 11th rib. ***9th to 11th rib*** - The **spleen** is located in the **left upper quadrant** of the abdomen, deep to the 9th, 10th, and 11th ribs. - Its protected position beneath these ribs makes it vulnerable to injury from trauma to the left lower chest or upper abdomen. *5th to 9th rib* - This range primarily covers the location of the **heart** and the upper part of the **lungs**. - While the spleen is superior to other abdominal organs, it does not extend as high as the 5th rib. *2nd to 5th rib* - This region is mainly associated with the **upper lobes of the lungs** and the **superior mediastinum**. - The spleen is an abdominal organ and is situated much lower in the thoracic cavity. *11th to 12th rib* - This range is too low and posterior for the typical position of the spleen, especially for its superior border. - The 12th rib primarily overlies the **kidneys** and the more inferior aspects of the diaphragm.

Q: Which of the following is not a branch of the inferior mesenteric artery?

Middle rectal. ***Middle rectal artery*** - The **middle rectal artery** [2] is typically a branch of the **internal iliac artery** [2], supplying the middle part of the rectum. - It is not a direct branch of the inferior mesenteric artery. *Left colic artery* - The left colic artery is a direct branch of the **inferior mesenteric artery** [1], supplying the distal transverse colon and descending colon. - It forms an important anastomosis with the middle colic artery [1]. *Superior rectal artery* - The **superior rectal artery** is the terminal branch of the **inferior mesenteric artery**, supplying the upper rectum. - This artery provides the primary arterial supply to the proximal large intestine structures. *Sigmoidal artery* - The **sigmoidal arteries** are typically 2-4 branches arising from the **inferior mesenteric artery**, supplying the sigmoid colon. - These arteries anastomose with branches of the superior rectal and left colic arteries.

Q: Which of the following is NOT a branch of 1st part of maxillary artery?

Greater palatine artery. ***Greater palatine artery*** - This artery is a branch of the **third part** of the maxillary artery, which supplies the palate. - The third part of the maxillary artery (also known as the pterygopalatine part) gives off branches that pass through the pterygopalatine fossa. *Middle meningeal artery* - This is a significant branch of the **first part** of the maxillary artery, entering the cranial cavity via the **foramen spinosum** to supply the dura mater. - It is often injured in head trauma, leading to an **epidural hematoma**. *Accessory meningeal artery* - This artery also arises from the **first part** of the maxillary artery and enters the skull through the **foramen ovale** to supply the dura mater. - It is a smaller branch compared to the middle meningeal artery. *Inferior alveolar artery* - It is a branch of the **first part** of the maxillary artery, descending to enter the mandible via the **mandibular foramen** to supply the teeth and bone of the mandible. - It gives off the **mylohyoid branch** before entering the mandibular foramen.

Q: Which of the following enzymes uses citrate in fatty acid synthesis?

ATP citrate lyase. ***ATP citrate lyase*** - This enzyme is crucial for fatty acid synthesis, as it cleaves **citrate** in the cytoplasm to generate **acetyl-CoA** and oxaloacetate. - The acetyl-CoA produced is then used as the primary building block for **fatty acid synthesis**. *Aconitase* - This enzyme isomerizes **citrate** to isocitrate within the **Krebs cycle** (TCA cycle) in the mitochondria. - It does not directly participate in the cytosolic pathway of fatty acid synthesis. *Citrate synthase* - This enzyme synthesizes **citrate** from acetyl-CoA and oxaloacetate, initiating the **Krebs cycle** in the mitochondrial matrix. - It is involved in citrate formation, not its utilization for fatty acid synthesis in the cytoplasm. *Malic enzyme* - This enzyme converts **malate** to pyruvate, generating **NADPH** in the cytoplasm. - While NADPH is essential for fatty acid synthesis, malic enzyme does not directly use citrate.

Q: Which of the following statements is true regarding medium chain fatty acids?

All of the options are true. ***All of the options are true*** - This option is correct because medium-chain fatty acids (MCFAs) possess unique metabolic properties that differentiate them from long-chain fatty acids (LCFAs), making all listed statements accurate. - Their shorter chain length allows for distinct digestion, absorption, and metabolic fates, which are beneficial in various clinical contexts. *Do not require pancreatic lipase for digestion* - MCFAs have **shorter carbon chains** (typically 6-12 carbons) and are more hydrophilic than LCFAs. - This property allows them to be digested by **lingual and gastric lipases** to a greater extent, reducing the reliance on pancreatic lipase. *Absorb directly into portal circulation* - Unlike LCFAs, which are re-esterified into triglycerides, packaged into **chylomicrons**, and absorbed into the lymphatic system, MCFAs are absorbed directly into the **portal vein**. - This bypasses the lymphatic system and directly transports them to the liver, making them a rapid energy source. *Are less likely to be deposited in adipose tissue compared to long-chain fatty acids* - MCFAs are **rapidly oxidized** in the liver for energy via beta-oxidation and are less likely to be stored as triglycerides in adipose tissue. - They are also not efficiently utilized for the synthesis of complex lipids or stored fat due to their unique metabolic pathway and preference for oxidation.

Q: What cofactor is required for the proper functioning of glucose-6-phosphate dehydrogenase?

NADP. ***NADP*** - **NADP+** (nicotinamide adenine dinucleotide phosphate) acts as the **electron acceptor** in the **glucose-6-phosphate dehydrogenase (G6PD)** reaction, becoming **NADPH**. - **NADPH** is crucial for maintaining the **redox balance** in cells, particularly in red blood cells, by reducing **oxidative stress**. *NAD* - **NAD+** (nicotinamide adenine dinucleotide) is a primary cofactor for many **dehydrogenase reactions** in catabolic pathways like **glycolysis** and the **Krebs cycle**. - It primarily functions as an electron acceptor in pathways that generate **ATP**, distinct from the role of **NADPH** in reductive biosynthesis and antioxidant defense. *FAD* - **FAD** (flavin adenine dinucleotide) is a coenzyme derived from **riboflavin (vitamin B2)** that is involved in various redox reactions, often in the form of **flavoproteins**. - Enzymes like **succinate dehydrogenase** in the electron transport chain utilize **FAD** as an electron acceptor, which is not the case for G6PD. *FMN* - **FMN** (flavin mononucleotide) is another coenzyme derived from **riboflavin**, structurally similar to FAD but lacking the additional adenosine monophosphate. - It participates in electron transfer reactions, particularly within **complex I** of the **electron transport chain**, but is not a cofactor for G6PD.

Q: In a person fasting overnight with carnitine deficiency, which of the following chemicals increase in quantity in blood?

Fatty acid levels. ***Fatty acid levels*** - **Carnitine deficiency** impairs the transport of **long-chain fatty acids** into the mitochondria for beta-oxidation. - This leads to an accumulation of **fatty acids** in the blood as they cannot be efficiently metabolized for energy during fasting. - Therefore, **fatty acid levels increase** in the blood. *Ketone body levels* - **Ketone bodies** are produced from the **beta-oxidation of fatty acids** in the liver. - With **carnitine deficiency**, fatty acid oxidation is impaired, thus **reducing** the production of ketone bodies, not increasing them. *Glucose levels* - During **fasting**, the body relies on **gluconeogenesis** and **glycogenolysis** to maintain glucose levels. - With carnitine deficiency primarily affecting fat metabolism and preventing fatty acid utilization, the body cannot spare glucose effectively. - This leads to **hypoglycemia** (decreased glucose), not increased glucose levels. *Amino acid levels* - **Amino acid metabolism** is largely independent of **carnitine**. - While amino acids can be used for gluconeogenesis during fasting, carnitine deficiency does not directly cause an increase in circulating amino acid levels.

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: Which amino acids are involved in the formation of purines?

Aspartate, glycine, glutamine. ***Aspartate, glycine, glutamine*** - **Glycine** provides the largest single contribution to the purine ring structure: carbons at positions 4 and 5, and nitrogen at position 7 (the entire glycine molecule is incorporated). - **Aspartate** contributes the nitrogen atom at position 1 of the purine ring. - **Glutamine** donates two nitrogen atoms to the purine ring, specifically at positions 3 and 9. *Aspartate, glycine* - While both **aspartate** and **glycine** are crucial, **glutamine** is also required for the complete synthesis of the purine ring, contributing two nitrogen atoms. - Omission of glutamine makes this option incomplete for the full complement of amino acids involved. *Aspartate, glutamate* - **Glutamate** is not directly involved as an amino acid precursor contributing atoms to the purine ring structure. - **Glutamine**, an amide of glutamate, is the active donor of nitrogen atoms for purine synthesis. *Aspartic acid, glycine, uric acid* - **Aspartic acid** is another name for aspartate, and **glycine** is correctly identified as a precursor. - However, **uric acid** is the end product of purine catabolism, not an amino acid involved in its synthesis.

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.

Question 1

From which ribs does the spleen extend?

Accepted Answer

9th to 11th rib

Answer

5th to 9th rib

Answer

2nd to 5th rib

Answer

11th to 12th rib

Question 2

Which of the following is not a branch of the inferior mesenteric artery?

Accepted Answer

Middle rectal

Answer

Left colic

Answer

Superior rectal

Answer

Sigmoidal artery

Question 3

Which of the following is NOT a branch of 1st part of maxillary artery?

Accepted Answer

Greater palatine artery

Answer

Accessory meningeal artery

Answer

Inferior alveolar artery

Answer

Middle meningeal artery

Question 4

Which of the following enzymes uses citrate in fatty acid synthesis?

Accepted Answer

ATP citrate lyase

Answer

Aconitase

Answer

Malic enzyme

Answer

Citrate synthase

Question 5

Which of the following statements is true regarding medium chain fatty acids?

Accepted Answer

All of the options are true

Answer

Do not require pancreatic lipase for digestion

Answer

Absorb directly into portal circulation

Answer

Are less likely to be deposited in adipose tissue compared to long-chain fatty acids

Question 6

What cofactor is required for the proper functioning of glucose-6-phosphate dehydrogenase?

Accepted Answer

NADP

Answer

NAD

Answer

FAD

Answer

FMN

Question 7

In a person fasting overnight with carnitine deficiency, which of the following chemicals increase in quantity in blood?

Accepted Answer

Fatty acid levels

Answer

Ketone body levels

Answer

Glucose levels

Answer

Amino acid levels

Question 8

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

Accepted Answer

Poly-A tail

Answer

CCA

Answer

Intron

Answer

7-methylguanosine

Question 9

Which amino acids are involved in the formation of purines?

Accepted Answer

Aspartate, glycine, glutamine

Answer

Aspartate, glycine

Answer

Aspartate, glutamate

Answer

Aspartic acid, glycine, uric acid

Question 10

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

NEET-PG 2012

Anatomy

Biochemistry

Pathology