NEET-PG 2013 Practice Questions

Q: Which muscle is the deepest in the anterior neck region?

Longus colli. ***Longus colli*** - The **longus colli** muscle is the **deepest muscle** located in the anterior neck region, running along the front of the cervical vertebral column from C1 to T3. - It lies in the **prevertebral layer**, deep to all other anterior neck structures including the carotid sheath, visceral compartment, and superficial muscles. - Its position directly anterior to the vertebral bodies makes it the deepest anterior neck muscle. *Platysma* - The platysma is the **most superficial muscle** of the neck, located just beneath the skin in the superficial fascia. - It is not a deep muscle and lies superficial to all other neck muscles. *Sternocleidomastoid* - The sternocleidomastoid is enclosed within the **investing layer of deep cervical fascia**, making it relatively superficial. - While prominent in the anterior and lateral neck, it is not the deepest anterior neck muscle. *Trapezius* - The trapezius is a large, **superficial muscle of the back and posterior neck**. - It is not located in the anterior neck and is a superficial, not deep, muscle.

Q: Superior wall of middle ear is formed by ?

Tegmen tympani. ***Tegmen tympani*** - The **tegmen tympani** is a thin plate of **petrous temporal bone** that forms the roof or superior wall of the middle ear cavity. - This structure separates the middle ear from the **middle cranial fossa** and its contents, including the **temporal lobe of the brain**. *Jugular bulb* - The **jugular bulb** is the dilated superior portion of the **internal jugular vein** and forms part of the **floor (inferior wall)** of the middle ear cavity, not the superior wall. - Its close proximity to the middle ear makes it vulnerable to injury during otologic surgery. *Tympanic membrane* - The **tympanic membrane** (eardrum) forms the **lateral wall** of the middle ear cavity, separating it from the external auditory canal. - It is crucial for **sound transmission** by vibrating in response to sound waves. *Carotid wall* - The **carotid wall** forms the **anterior wall** of the middle ear cavity and is related to the **internal carotid artery** as it narrows through the carotid canal. - This wall is not the superior boundary of the middle ear.

Q: What is the half-life of Prealbumin?

2 days. ***2 days*** - Prealbumin, also known as transthyretin, has a **short half-life** of approximately 2-3 days, making it a sensitive indicator of recent changes in **nutritional status**. - Its rapid turnover allows for prompt reflection of improvement or deterioration in protein synthesis. *10 days* - A half-life of 10 days would make prealbumin less responsive to acute changes in nutrition compared to its actual turnover rate. - This duration is longer than the typical half-life of proteins used to monitor **short-term nutritional status**. *20 days* - A 20-day half-life would indicate a protein with a much slower turnover, unsuitable for monitoring **acute nutritional interventions**. - Proteins with such long half-lives, like **albumin**, reflect more chronic states rather than rapid changes. *40 days* - A half-life of 40 days is characteristic of proteins like **albumin**, which are influenced by longer-term nutritional and inflammatory processes. - Such a long half-life would not be useful for assessing immediate responses to **nutritional support** or acute disease states.

Q: Which of the following organs does not primarily utilize fatty acids for energy?

Brain. ***Brain*** - The **brain primarily uses glucose** as its main energy source because fatty acids cannot efficiently cross the **blood-brain barrier**. - During prolonged starvation, the brain can adapt to use **ketone bodies**, which are derived from fatty acid breakdown in the liver. *Muscle* - **Skeletal muscle** can utilize both **glucose and fatty acids** for energy, with fatty acids becoming a more prominent fuel source during prolonged exercise and at rest. - **Cardiac muscle** (heart) heavily relies on **fatty acid oxidation** as its primary energy substrate, especially during basal conditions. *Liver* - The **liver is highly metabolically flexible** and readily oxidizes fatty acids for its own energy needs, particularly during fasting states. - It also plays a key role in **fatty acid metabolism**, including synthesis, breakdown, and conversion into ketone bodies. *Kidney* - The **renal cortex** is rich in mitochondria and has a high metabolic rate, primarily utilizing **fatty acid oxidation** to meet its significant energy demands for filtration and reabsorption. - While the renal medulla can use glucose, the cortex's reliance on fatty acids makes it a significant consumer.

Q: Trypsinogen is converted to trypsin by?

Removal of specific amino acids from trypsinogen. ***Removal of specific amino acids from trypsinogen*** - Trypsinogen is an **inactive zymogen** that is activated by the enzymatic cleavage of a **short N-terminal peptide**. - This cleavage event, primarily catalyzed by **enteropeptidase** (or trypsin itself), transforms trypsinogen into active **trypsin**, a process known as **proteolytic activation**. *Combination of 2 molecules of trypsinogen* - The activation of trypsinogen to trypsin is a **unimolecular conformational change** followed by proteolytic cleavage, not a combination reaction between two zymogen molecules. - While trypsin can activate other trypsinogen molecules, the initial activation does not involve the physical combination of two zymogen molecules. *Phosphorylation* - **Phosphorylation** is a common regulatory mechanism in proteins but is not the primary method for activating inactive trypsinogen. - Trypsinogen activation relies on a **proteolytic cleavage event**, rather than the addition of a phosphate group. *Addition of alkyl group* - The addition of an **alkyl group** is not a known mechanism for the physiological activation of trypsinogen. - Enzymatic activation typically involves **hydrolysis of peptide bonds** or other specific post-translational modifications.

Q: What is the primary condition associated with positive anti-dsDNA antibodies?

SLE. ***SLE*** - **Anti-dsDNA antibodies** are a highly specific marker for **Systemic Lupus Erythematosus (SLE)** and are included in its diagnostic criteria [1]. - The levels of **anti-dsDNA antibodies** can also correlate with disease activity, particularly in cases of **lupus nephritis** [1]. *RA* - **Rheumatoid Arthritis (RA)** is primarily associated with **rheumatoid factor (RF)** and **anti-citrullinated protein antibodies (ACPA)** or **anti-CCP antibodies**. - While ANA (antinuclear antibodies) can be positive in RA, **anti-dsDNA antibodies** are not a characteristic serological marker [1]. *Scleroderma* - **Scleroderma**, or systemic sclerosis, is characterized by specific antibodies such as **anti-Scl-70 (topoisomerase I)**, **anti-centromere antibodies**, and **anti-RNA polymerase III antibodies**, depending on the subtype. - **Anti-dsDNA antibodies** are not typically found in scleroderma and do not play a role in its diagnosis [1]. *PAN* - **Polyarteritis Nodosa (PAN)** is a **necrotizing vasculitis** of medium-sized arteries and is not associated with **anti-dsDNA antibodies**. - PAN is generally considered an **ANCA-negative vasculitis**, and its diagnosis relies more on clinical features, angiography, and biopsy findings.

Q: Which of the following is not an obstructive lung disease?

Interstitial fibrosis. ***Interstitial fibrosis*** - **Interstitial fibrosis** is a **restrictive lung disease**, characterized by **reduced lung elasticity** and lung volumes, rather than airway obstruction [1]. - In this condition, the **lung tissue becomes scarred and stiff**, making it difficult to expand fully during inspiration [1]. *Emphysema* - **Emphysema** is a classic **obstructive lung disease** caused by the destruction of the **alveolar walls**, leading to enlarged air spaces and loss of elastic recoil [3]. - This destruction results in **airflow limitation**, particularly during exhalation, as airways collapse prematurely. *Asthma* - **Asthma** is an **obstructive lung disease** characterized by **reversible airway inflammation**, bronchoconstriction, and increased mucus production [2]. - These factors lead to **episodic airflow obstruction**, making it difficult to breathe, especially during exacerbations [2]. *Bronchitis* - **Bronchitis**, particularly **chronic bronchitis**, is an **obstructive lung disease** defined by chronic inflammation of the bronchi. - This inflammation causes **mucus hypersecretion** and narrowing of the airways, leading to persistent cough and airflow limitation.

Q: What is the primary action observed in the withdrawal reflex?

Flexion. ***Flexion*** - The **withdrawal reflex** is a protective reflex that causes the affected limb to **flex** and withdraw from a painful stimulus. - This **flexion** is mediated by the contraction of flexor muscles and relaxation of extensor muscles, moving the limb away from danger. *Extension* - **Extension** is the opposite of flexion and would move the limb closer to or maintain its position relative to the painful stimulus. - This action is typically observed in the **crossed extensor reflex**, where the contralateral limb extends to support the body, not in the direct withdrawal of the stimulated limb. *Flexion followed by extension* - While **flexion** is the primary action, it is not typically followed immediately by extension within the same limb in a simple withdrawal reflex. - If a coordinated movement were to occur, such as shifting weight, the **crossed extensor reflex** would involve extension in the opposite limb. *Not applicable* - The withdrawal reflex involves a clear and defined muscle action which is **flexion**, making "not applicable" incorrect. - This reflex is a fundamental component of the nervous system's response to noxious stimuli.

Q: Which of the following is classified as a pain receptor?

Free nerve endings. ***Free nerve endings*** - **Free nerve endings** are the most common type of sensory receptor in the skin and are responsible for detecting **pain**, temperature, and crude touch. - They lack specialized structures and are found throughout the epidermis and dermis. *Meissner's corpuscle* - **Meissner's corpuscles** are encapsulated nerve endings that detect **light touch** and **vibration**. - They are rapidly adapting and are abundant in sensitive, hairless skin areas like fingertips and lips. *Pacinian corpuscle* - **Pacinian corpuscles** are large, encapsulated receptors that detect **deep pressure** and **vibration**. - They are rapidly adapting and respond to high-frequency stimuli. *Merkel disc* - **Merkel discs** are specialized epithelial cells associated with nerve endings that detect **sustained pressure** and **texture**. - They are slowly adapting receptors crucial for tactile discrimination.

Q: Which of the following statements is true regarding post-ganglionic parasympathetic fibers?

They release acetylcholine at the target organs.. ***They release acetylcholine at the target organs.*** - Post-ganglionic parasympathetic fibers are **cholinergic**, meaning they release the neurotransmitter **acetylcholine** at their effector organs. - This action mediates the characteristic "rest and digest" responses of the parasympathetic nervous system. *They originate from the spinal cord.* - **Pre-ganglionic parasympathetic fibers** originate from the **brainstem** (cranial nerves III, VII, IX, X) and the **sacral spinal cord** (S2-S4). - Post-ganglionic fibers originate in ganglia located near or within their target organs, not the spinal cord directly. *They are part of the sympathetic nervous system.* - Post-ganglionic parasympathetic fibers are a component of the **parasympathetic nervous system**, not the sympathetic nervous system. - The sympathetic and parasympathetic systems are distinct divisions of the autonomic nervous system with generally opposing functions. *They are responsible for 'fight or flight' responses.* - The **'fight or flight' response** is characteristic of the **sympathetic nervous system**, which prepares the body for stressful situations. - The parasympathetic nervous system is responsible for **'rest and digest' functions**, promoting energy conservation and maintenance activities.

Question 1

Which muscle is the deepest in the anterior neck region?

Accepted Answer

Longus colli

Answer

Sternocleidomastoid

Answer

Platysma

Answer

Trapezius

Question 2

Superior wall of middle ear is formed by ?

Accepted Answer

Tegmen tympani

Answer

Jugular bulb

Answer

Tympanic membrane

Answer

Carotid wall

Question 3

What is the half-life of Prealbumin?

Accepted Answer

2 days

Answer

10 days

Answer

20 days

Answer

40 days

Question 4

Which of the following organs does not primarily utilize fatty acids for energy?

Accepted Answer

Brain

Answer

Muscle

Answer

Liver

Answer

Kidney

Question 5

Trypsinogen is converted to trypsin by?

Accepted Answer

Removal of specific amino acids from trypsinogen

Answer

Combination of 2 molecules of trypsinogen

Answer

Phosphorylation

Answer

Addition of alkyl group

Question 6

What is the primary condition associated with positive anti-dsDNA antibodies?

Accepted Answer

SLE

Answer

RA

Answer

Scleroderma

Answer

PAN

Question 7

Which of the following is not an obstructive lung disease?

Accepted Answer

Interstitial fibrosis

Answer

Emphysema

Answer

Asthma

Answer

Bronchitis

Question 8

What is the primary action observed in the withdrawal reflex?

Accepted Answer

Flexion

Answer

Extension

Answer

Flexion followed by extension

Answer

Not applicable

Question 9

Which of the following is classified as a pain receptor?

Accepted Answer

Free nerve endings

Answer

Meissner's corpuscle

Answer

Pacinian corpuscle

Answer

Merkel disc

Question 10

Which of the following statements is true regarding post-ganglionic parasympathetic fibers?

Accepted Answer

They release acetylcholine at the target organs.

Answer

They originate from the spinal cord.

Answer

They are part of the sympathetic nervous system.

Answer

They are responsible for 'fight or flight' responses.

NEET-PG 2013

Anatomy

Biochemistry

Internal Medicine

Pathology

Physiology