NEET-PG 2012 Practice Questions

Q: The thyrocervical trunk is a branch of which part of subclavian artery?

1st part. ***1st part*** - The **thyrocervical trunk** is one of the three primary branches arising from the **first part** of the subclavian artery. - The first part lies medial to the **anterior scalene muscle**. *2nd part* - The **second part** of the subclavian artery gives rise to the **costocervical trunk**. - This part lies posterior to the **anterior scalene muscle**. *3rd part* - The **third part** of the subclavian artery typically has no branches or may give off the **dorsal scapular artery**. - This part lies lateral to the **anterior scalene muscle**. *4th part* - This option is incorrect as the **subclavian artery has only three parts**, divided by their relationship to the anterior scalene muscle. - There is no anatomical fourth part of the subclavian artery.

Q: What is the typical length of a human sperm cell?

55 micrometers. ***55 micrometers*** - A typical **human sperm cell** measures approximately **55 micrometers** from the head to the tip of the tail [1]. - This length allows for efficient motility and navigation within the female reproductive tract to reach the ovum [1]. *100 micrometers* - This length is significantly **longer** than the average size of a human sperm cell. - While some cells can achieve this size, it is not typical for **spermatozoa**. *65 micrometers* - Although closer to the actual size, **65 micrometers** is generally considered slightly larger than the average human sperm cell length. - Sperm length is critical for understanding their **mobility** and **fertility** [1]. *50 micrometers* - This measurement is slightly **shorter** than the typical length of a human sperm cell. - The precise length, including the **head** and **flagellum**, contributes to its function.

Q: At which positions does pancreatic lipase hydrolyze the ester linkages of triacylglycerides?

1 and 3. **Correct: 1 and 3** - Pancreatic lipase specifically targets the **ester bonds at the sn-1 and sn-3 positions** (primary alcohol positions) on the glycerol backbone of triacylglycerides. - This positional specificity results in the formation of **2-monoacylglycerol (2-MAG)** and **two free fatty acids**. - This is the characteristic action of pancreatic triacylglycerol lipase during fat digestion in the intestinal lumen. *Incorrect: 1 and 2* - Hydrolysis at positions 1 and 2 would produce a 3-monoacylglycerol and free fatty acids, which is not the physiological product of pancreatic lipase. - The enzyme's positional specificity favors the outer sn-1 and sn-3 positions, not the middle sn-2 position. *Incorrect: 2 and 3* - Hydrolysis at positions 2 and 3 would yield a 1-monoacylglycerol and free fatty acids, which does not reflect pancreatic lipase activity. - The enzyme specifically spares the sn-2 position due to its structural specificity. *Incorrect: Only 3* - If only position 3 were hydrolyzed, the product would be a 1,2-diacylglycerol and one free fatty acid. - This represents incomplete hydrolysis; pancreatic lipase typically hydrolyzes **both outer positions (sn-1 and sn-3)** due to its regiospecificity.

Q: In which condition is venous blood most commonly observed to have a high hematocrit in routine clinical practice?

Dehydration. Dehydration - In **dehydration**, the total body water is reduced, leading to a decrease in plasma volume [1, 5]. This concentrates the red blood cells, resulting in a relatively **high hematocrit**. [3] - This is a common finding as the body attempts to conserve fluid, making it a primary cause of **elevated hematocrit** in clinical practice. *Anemia* - **Anemia** is characterized by a decrease in the number of red blood cells or a reduced hemoglobin concentration, which would lead to a **low hematocrit**, not a high one [2]. - This condition involves insufficient oxygen-carrying capacity due to a deficiency in red blood cells or hemoglobin [2]. *Hypervolemia* - **Hypervolemia** describes an excess of fluid in the blood, which would dilute the blood components, leading to a relatively **low hematocrit** [1]. - This condition is often associated with conditions like heart failure or kidney disease, where fluid retention is common. *Acute blood loss* - In **acute blood loss**, the loss of whole blood immediately after the event would initially reduce both red blood cells and plasma proportionally, not immediately raising hematocrit [2]. - As the body attempts to compensate by shifting extravascular fluid into the circulation, this would further dilute the blood, eventually leading to a **decreased hematocrit** [2].

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.

Q: Growth hormone level is highest during

Sleep. ***Sleep*** - Growth hormone (GH) secretion is **pulsatile**, with the largest and most consistent pulses occurring during **slow-wave sleep** (deep sleep). - This nocturnal surge contributes significantly to the overall daily GH output and is crucial for growth and metabolic regulation. *Hypoglycemia* - While **hypoglycemia** is a potent stimulus for GH release, it is an acute stress response rather than a state where GH levels are consistently highest. - The body's primary response to hypoglycemia is to raise blood glucose, and while GH helps, it is not the peak physiological secretion time. *Fasting* - **Prolonged fasting** can increase GH secretion as a mechanism to mobilize fat stores and conserve glucose. - However, the peak levels due to fasting are generally less pronounced than the dramatic surge observed during deep sleep. *Exercise* - **Vigorous exercise** can acutely stimulate GH release, particularly with sustained effort. - This increase is typically transient and not as high or consistently cyclical as the secretion during nocturnal sleep.

Q: Diurnal variation of ACTH depends on ?

Suprachiasmatic nucleus. ***Suprachiasmatic nucleus*** - The **suprachiasmatic nucleus (SCN)** acts as the body's **master circadian clock**, synchronizing various physiological rhythms, including the **diurnal variation of ACTH** secretion. - It receives light input from the **retina** and projects to other brain regions to regulate the timing of hormone release. *Supraoptic nucleus* - The **supraoptic nucleus (SON)** is primarily involved in the production of **vasopressin (ADH)** and **oxytocin**, which are released by the posterior pituitary. - It does not directly control the diurnal rhythm of ACTH. *Ventrolateral nucleus* - The **ventrolateral preoptic area (VLPO)** is a key region for **sleep regulation**, promoting sleep by inhibiting wake-promoting neurotransmitters. - While it contributes to sleep-wake cycles, it is not the primary regulator of ACTH's diurnal variation. *Thalamus* - The **thalamus** is a major relay center for sensory information and plays a role in consciousness, sleep, and alertness. - It does not directly control the **circadian rhythm of ACTH secretion**.

Q: What is the effect of acetylcholine on the Lower Esophageal Sphincter (LES)?

Causes contraction. ***Correct Option: Causes contraction*** - Acetylcholine acts on **M3 muscarinic receptors** on LES smooth muscle cells to cause **contraction** - This is part of the **excitatory cholinergic pathway** that maintains LES tone and prevents gastroesophageal reflux - Acetylcholine is released from **excitatory motor neurons** in the myenteric plexus *Incorrect: Causes relaxation* - LES relaxation during swallowing is mediated by **nitric oxide (NO)** and **vasoactive intestinal peptide (VIP)**, NOT acetylcholine - These inhibitory neurotransmitters are released from separate **inhibitory motor neurons** - The relaxation response during swallowing is due to activation of the inhibitory pathway, which suppresses cholinergic tone *Incorrect: No effect on LES* - Acetylcholine has a significant effect on the LES - It is one of the key neurotransmitters maintaining basal LES tone - Loss of cholinergic input can lead to decreased LES pressure *Incorrect: Contraction followed by relaxation* - Acetylcholine itself causes only contraction - The swallowing reflex involves coordinated activation of inhibitory (NO/VIP) and suppression of excitatory (acetylcholine) pathways - The sequence of events is neural, not a biphasic response to acetylcholine alone

Question 1

The thyrocervical trunk is a branch of which part of subclavian artery?

Accepted Answer

1st part

Answer

2nd part

Answer

3rd part

Answer

4th part

Question 2

What is the typical length of a human sperm cell?

Accepted Answer

55 micrometers

Answer

50 micrometers

Answer

100 micrometers

Answer

65 micrometers

Question 3

Which statement accurately describes a characteristic of synovial joints?

Accepted Answer

Hyaline cartilage covers the articular surfaces of synovial joints.

Answer

The metacarpo-phalangeal joint is a condyloid joint.

Answer

Cartilage can sometimes divide the joint into two cavities.

Answer

Stability is inversely proportional to mobility in synovial joints.

Question 4

At which positions does pancreatic lipase hydrolyze the ester linkages of triacylglycerides?

Accepted Answer

1 and 3

Answer

1 and 2

Answer

2 and 3

Answer

Only 3

Question 5

Which of the following statements about lung compliance is NOT true?

Accepted Answer

Measured by intrapleural pressure at different lung volumes.

Answer

Decreased at the height of inspiration.

Answer

Increased in emphysema.

Answer

Increased by surfactant.

Question 6

In which condition is venous blood most commonly observed to have a high hematocrit in routine clinical practice?

Accepted Answer

Dehydration

Answer

Anemia

Answer

Hypervolemia

Answer

Acute blood loss

Question 7

Prostaglandins (PGs) in semen are secreted by?

Accepted Answer

Seminal vesicle

Answer

Prostate

Answer

Sperms

Answer

Testes

Question 8

Growth hormone level is highest during

Accepted Answer

Sleep

Answer

Hypoglycemia

Answer

Fasting

Answer

Exercise

Question 9

Diurnal variation of ACTH depends on ?

Accepted Answer

Suprachiasmatic nucleus

Answer

Supraoptic nucleus

Answer

Ventrolateral nucleus

Answer

Thalamus

Question 10

What is the effect of acetylcholine on the Lower Esophageal Sphincter (LES)?

Accepted Answer

Causes contraction

Answer

Causes relaxation

Answer

No effect on LES

Answer

Contraction followed by relaxation

NEET-PG 2012

Anatomy

Biochemistry

Physiology