NEET-PG 2012 Practice Questions

Q: All are lateral branches of the abdominal aorta, EXCEPT which of the following?

Celiac trunk. ***Celiac trunk*** - The **celiac trunk** is an anterior branch of the abdominal aorta, supplying the foregut derivatives. - It arises from the ventral aspect of the aorta, distinguishing it from lateral branches. *Right testicular artery* - The **testicular arteries** (gonadal arteries) are paired lateral branches of the abdominal aorta. - They arise inferior to the renal arteries and descend to supply the testes in males. *Left renal artery* - The **renal arteries** [1] [3] are large paired lateral branches of the abdominal aorta. - They supply the kidneys [2] and typically arise just inferior to the superior mesenteric artery. *Middle suprarenal artery* - The **middle suprarenal arteries** are paired lateral branches, typically arising directly from the abdominal aorta. - They supply the suprarenal (adrenal) glands [2].

Q: Nucleus gracilis and nucleus cuneatus are seen in?

Medulla. ***Medulla*** - The **nucleus gracilis** and **nucleus cuneatus** are located in the **dorsal medulla** and are crucial for processing **conscious proprioception**, **vibration**, and **fine touch**. - These nuclei receive input from the fasciculus gracilis and fasciculus cuneatus (dorsal column tracts) and are part of the dorsal column-medial lemniscus pathway. - They give rise to the **internal arcuate fibers** which decussate and form the **medial lemniscus**. *Pons* - The pons contains several important nuclei, including the **pontine nuclei** (involved in motor coordination), nuclei of cranial nerves V, VI, VII, and VIII, and the **locus coeruleus**. - The dorsal column nuclei are not located in the pons. *Temporal lobe* - The **temporal lobe** is part of the cerebral cortex and is primarily involved in **auditory processing**, memory formation, and language comprehension. - It contains structures like the hippocampus and amygdala, but not the dorsal column nuclei. *Midbrain* - The **midbrain** contains nuclei such as the **red nucleus**, **substantia nigra**, and nuclei of cranial nerves III and IV, involved in motor control and eye movements. - The nucleus gracilis and nucleus cuneatus are not found in the midbrain.

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 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: Mutation in GLUT-2 causes which syndrome?

Fanconi-Bickel syndrome. ***Fanconi-Bickel syndrome*** - This syndrome is caused by a **mutation in the GLUT-2 gene**, leading to dysfunctional glucose transport in the liver, kidneys, and intestines. - Key features include **hepatorenal glycogen accumulation**, **renal tubulopathy** (Fanconi syndrome), and **impaired glucose and galactose utilization**. *Dandy-Walker syndrome* - This is a **congenital brain malformation** involving the cerebellum and fourth ventricle. - It is often associated with hydrocephalus, but not directly linked to glucose transporter defects. *Beckwith-Wiedemann syndrome* - This is an **overgrowth disorder** characterized by a high risk of childhood cancer and congenital anomalies. - It is primarily caused by genetic abnormalities on **chromosome 11p15.5** and is unrelated to GLUT-2 mutations. *Menke's disease* - This is a rare X-linked recessive disorder of **copper metabolism**, leading to severe neurological degeneration. - It results from mutations in the **ATP7A gene**, which encodes a copper-transporting ATPase.

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: What is the role of Apoprotein C-II in lipid metabolism?

Activates lipoprotein lipase. ***Activates lipoprotein lipase*** - **Apoprotein C-II (ApoC-II)** is a crucial **activator** of **lipoprotein lipase (LPL)**. - LPL is an enzyme responsible for **hydrolyzing triglycerides** from chylomicrons and VLDL, allowing fatty acids to be taken up by tissues. - **Deficiency of ApoC-II** leads to severe hypertriglyceridemia due to inability to activate LPL. *Inhibits lipoprotein lipase* - This is the function of **ApoC-III**, not ApoC-II. - ApoC-III **inhibits LPL activity**, which is the opposite role of ApoC-II. *Facilitates triglyceride transport* - While apoproteins are essential for **assembly and transport of lipoproteins** that carry triglycerides, this is not the specific primary role of ApoC-II. - ApoC-II's primary function is **regulating LPL enzyme activity**, not direct transport facilitation. *None of the options* - This is incorrect because ApoC-II clearly **activates lipoprotein lipase**, which is one of the given options.

Q: According to some older studies, which sperm chromosome was hypothesized to be associated with faster initial motility?

Y chromosome. ***Y chromosome*** - **Older hypothesis** suggested that Y chromosome-bearing sperm might be faster due to being slightly smaller and lighter - However, **modern rigorous studies have largely debunked this theory** - The chromosomal size difference (X vs Y) represents less than 0.02% of total sperm mass, making any speed difference negligible - **Current scientific consensus**: No consistent, reproducible motility difference has been demonstrated *X chromosome* - X-bearing sperm are marginally larger due to more DNA content - Early theories suggested they were slower but more robust - **Modern evidence does not support consistent motility differences** between X and Y bearing sperm *Both same* - This actually reflects the **current scientific consensus** based on modern flow cytometry and separation studies - Most rigorous contemporary research shows no reliable motility differences between X and Y chromosome-bearing sperm - The Ericsson albumin method (based on speed separation) has been largely discredited *None of the options* - This option is incorrect as the question asks about historical hypotheses - Early studies did propose the Y chromosome theory, even though it's now considered largely inaccurate

Q: What is the normal range for the CSF/plasma glucose ratio?

0.6 - 0.8. ***Correct: 0.6 - 0.8*** - This ratio indicates that cerebrospinal fluid (CSF) glucose concentration is typically 60-80% of plasma glucose concentration - This range is crucial for identifying metabolic or infectious pathologies affecting the central nervous system - Normal CSF glucose is approximately 50-80 mg/dL when plasma glucose is 70-120 mg/dL *Incorrect: 0.2 - 0.4* - A ratio in this range indicates significantly low CSF glucose, suggesting conditions like bacterial meningitis or hypoglycorrhachia - This is well below the normal physiological proportion of glucose in the CSF relative to plasma - Seen in bacterial/tuberculous meningitis, fungal infections, or malignancy *Incorrect: 1.0 - 1.2* - A CSF/plasma glucose ratio close to or above 1.0 would imply that CSF glucose levels are equal to or higher than plasma levels, which is physiologically impossible under normal conditions - Glucose transport into the CSF is regulated by GLUT-1 transporters and typically results in lower concentrations than in plasma - The blood-brain barrier maintains this gradient *Incorrect: 1.2 - 1.6* - This range is even more exaggerated and physiologically impossible, as CSF glucose cannot exceed plasma glucose in a healthy individual - Such a high ratio would contradict the mechanisms of glucose transport across the blood-brain barrier - Would suggest laboratory error if observed

Q: Prostaglandins (PGs) in semen are secreted by?

Seminal vesicle. ***Seminal vesicle*** - The **seminal vesicles** are the primary source of **prostaglandins (PGs)** in semen, contributing significantly to the seminal fluid volume. - These PGs play a crucial role in promoting **sperm motility** and facilitating fertilization. *Prostate* - The **prostate gland** primarily secretes **citrate**, **acid phosphatase**, and **prostate-specific antigen (PSA)**, which contribute to sperm activation and semen liquefaction. - It does not significantly contribute to the prostaglandin content of semen. *Sperms* - **Spermatozoa** themselves primarily contribute genetic material and are not a significant source of prostaglandin synthesis in semen. - Their main function is fertilization, not the production of accessory gland secretions. *Testes* - The **testes** are responsible for **spermatogenesis** (sperm production) and the synthesis of **androgens** like testosterone. - They do not secrete prostaglandins into the seminal fluid.

Question 1

All are lateral branches of the abdominal aorta, EXCEPT which of the following?

Accepted Answer

Celiac trunk

Answer

Right testicular artery

Answer

Left renal artery

Answer

Middle suprarenal artery

Question 2

Nucleus gracilis and nucleus cuneatus are seen in?

Accepted Answer

Medulla

Answer

Temporal lobe

Answer

Midbrain

Answer

Pons

Question 3

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

Accepted Answer

Poly-A tail

Answer

CCA

Answer

Intron

Answer

7-methylguanosine

Question 4

What is the primary metal ion found in myoglobin?

Accepted Answer

Iron

Answer

Copper

Answer

Selenium

Answer

Zinc

Question 5

Mutation in GLUT-2 causes which syndrome?

Accepted Answer

Fanconi-Bickel syndrome

Answer

Dandy walker syndrome

Answer

Beckwith-Wiedemann syndrome

Answer

Menke's disease

Question 6

Anaplerotic reaction is catalyzed by?

Accepted Answer

Pyruvate carboxylase

Answer

Enolase

Answer

Pyruvate kinase

Answer

G6PD

Question 7

What is the role of Apoprotein C-II in lipid metabolism?

Accepted Answer

Activates lipoprotein lipase

Answer

None of the options

Answer

Inhibits lipoprotein lipase

Answer

Facilitates triglyceride transport

Question 8

According to some older studies, which sperm chromosome was hypothesized to be associated with faster initial motility?

Accepted Answer

Y chromosome

Answer

None of the options

Answer

X chromosome

Answer

Both same

Question 9

What is the normal range for the CSF/plasma glucose ratio?

Accepted Answer

0.6 - 0.8

Answer

1.2 - 1.6

Answer

0.2 - 0.4

Answer

1.0 - 1.2

Question 10

Prostaglandins (PGs) in semen are secreted by?

Accepted Answer

Seminal vesicle

Answer

Prostate

Answer

Sperms

Answer

Testes

NEET-PG 2012

Anatomy

Biochemistry

Physiology