NEET-PG 2015 Practice Questions

Q: Which of the following muscles is not attached to the medial border of the scapula?

Teres major. ***Teres major*** - The **teres major** muscle originates from the **inferior angle and lower part of the lateral border** of the scapula, NOT the medial border. - It inserts into the medial lip of the intertubercular groove of the humerus. - This is the correct answer as it does not attach to the medial border of the scapula. *Serratus anterior* - The **serratus anterior** muscle originates from the outer surfaces of the upper 8-9 ribs and inserts along the **entire medial border** of the scapula on its anterior (costal) surface. - It plays a crucial role in protraction and upward rotation of the scapula, keeping it applied to the thoracic wall. *Levator scapulae* - The **levator scapulae** muscle originates from the transverse processes of the C1-C4 vertebrae and inserts into the **superior angle and upper part of the medial border** of the scapula. - Its primary actions are to elevate the scapula and assist in downward rotation. *Rhomboid major* - The **rhomboid major** muscle originates from the spinous processes of T2-T5 vertebrae and attaches to the **medial border** of the scapula between the spine and inferior angle. - It acts to retract, elevate, and rotate the scapula downward.

Q: Which is the first steroid intermediate formed in the conversion of cholesterol to steroid hormones?

Pregnenolone. ***Pregnenolone*** - **Pregnenolone** is the **first steroid intermediate** formed from **cholesterol** in steroidogenesis - The conversion occurs in mitochondria via the **cholesterol side-chain cleavage enzyme (P450scc/CYP11A1)** - This is the **rate-limiting step** in steroid hormone biosynthesis - From pregnenolone, all other steroid hormones are subsequently synthesized *Progesterone* - Progesterone is the **second intermediate**, formed from pregnenolone - It serves as a precursor for glucocorticoids, mineralocorticoids, and androgens - Not the first intermediate from cholesterol *Glucocorticoid* - Glucocorticoids (e.g., cortisol) are **end products**, not intermediates - Formed several steps downstream from cholesterol via pregnenolone and progesterone *Mineralocorticoid* - Mineralocorticoids (e.g., aldosterone) are **end products**, not intermediates - Synthesized from progesterone through multiple enzymatic steps *Estradiol* - Estradiol is a **late-stage product** synthesized from androgens - Requires aromatase enzyme for conversion from testosterone - Multiple steps removed from the initial cholesterol conversion

Q: What is the immediate source of energy for cellular processes?

ATP. ***ATP*** - **Adenosine triphosphate (ATP)** is the direct and immediate source of energy for almost all cellular processes, including **muscle contraction**, **active transport**, and **biosynthesis**. - Its high-energy phosphate bonds release energy upon hydrolysis, driving various cellular functions. *Cori's cycle* - The **Cori cycle** involves the interconversion of **lactate** and **glucose** between the muscle and the liver to regenerate glucose stores. - It is an important metabolic pathway for glucose homeostasis during anaerobic conditions, but it does not directly provide immediate energy for cellular processes. *HMP* - The **Hexose Monophosphate Pathway (HMP)**, also known as the **pentose phosphate pathway**, primarily produces **NADPH** and **ribose-5-phosphate**. - While it generates NADPH for reductive biosynthesis and protects against oxidative stress, it is not an immediate source of energy. *TCA cycle* - The **Tricarboxylic Acid (TCA) cycle**, or Krebs cycle, is a central metabolic pathway that oxidizes **acetyl-CoA** to produce **ATP**, **NADH**, and **FADH2**. - While it is a major producer of ATP, it is not the *immediate* source; instead, it generates the precursors that fuel oxidative phosphorylation to produce ATP.

Q: Randomization is done to reduce?

Selection bias. ***Selection bias*** - **Randomization** ensures that each participant has an equal chance of being assigned to any study group, which helps to distribute both known and unknown confounding factors evenly. - This process minimizes **selection bias** by promoting comparability between groups, making it more likely that any observed differences are due to the intervention rather than pre-existing differences. *Recall bias* - **Recall bias** occurs when there are systematic differences in the way participants remember or report past exposures or events, often seen in retrospective studies. - While randomization helps control for confounding, it does not directly prevent participants from inaccurately recalling information. *Berksonian bias* - **Berksonian bias** is a form of selection bias where the probability of being admitted to a hospital (or selected into a study) is affected by the presence of a co-morbidity, leading to a distorted association between diseases. - Randomization aims to balance characteristics *within* the study groups once participants are recruited, but it doesn't address biases related to the initial selection into the study population from a larger source. *Reporting bias* - **Reporting bias** refers to selective revealing or suppression of information, either by study participants (e.g., social desirability bias) or by researchers (e.g., only reporting positive findings). - Randomization helps ensure internal validity by creating comparable groups, but it does not prevent individuals from selectively reporting outcomes or experiences.

Q: Which subtype of Acute Myeloid Leukemia (AML) is most commonly associated with gum hypertrophy?

Acute Myeloid Leukemia M4. ***M4*** - **Acute Myeloid Leukemia (AML) M4** is associated with **monocytic differentiation**, leading to gum hypertrophy due to infiltration of the gums by leukemic cells [1]. - Patients may present with **gingival bleeding**, pain, and swelling in addition to other systemic symptoms of leukemia. *M3* - Known as **acute promyelocytic leukemia**, it typically presents with **coagulopathy** and not gum hypertrophy [1]. - Characterized by **promyelocytes** with heavy granulation and the presence of **faggot cells** (auer rods) [1]. *M2* - Represents a **myeloblastic type** of acute leukemia but is less commonly associated with **gingival hyperplasia**. - Associated with **more typical myeloid features** and presents with **anemia** and **thrombocytopenia**. *M1* - This is a **minimally differentiated type** of acute myeloid leukemia with **myeloblasts** and no significant differentiating features like gum hypertrophy. - Often presents with **rapid onset of symptoms** related to bone marrow failure, rather than localized gum issues. **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. 620-622.

Q: Stapedius pulls stapes in which direction?

Posterior. ***Posterior*** - The **stapedius muscle** attaches to the **posterior surface of the stapes neck**. - Contraction of the stapedius muscle pulls the stapes **posteriorly and laterally** (posterolaterally), tilting the footplate away from the oval window and reducing sound transmission. - This action dampens excessive vibrations and protects the inner ear from loud sounds as part of the **acoustic reflex**. *Anterior* - Pulling the stapes anteriorly would push the footplate further into the **oval window**, which would increase sound transmission rather than dampen it. - No muscle pulls the stapes anteriorly in the context of the **acoustic reflex**. *Superior* - The stapedius muscle's action is primarily along the **posterolateral axis**, not superiorly. - Pulling superiorly would not effectively dampen sound vibrations or protect the inner ear from acoustic trauma. *Inferior* - The anatomy and function of the stapedius muscle do not support an inferior pulling action. - The stapedius acts to stabilize and retract the stapes **posterolaterally**, not inferiorly.

Q: Which of the following statements about Alport's syndrome is incorrect?

Autosomal dominant. ***Autosomal dominant*** - While there are rare autosomal dominant forms, the most common and classic presentation of **Alport's syndrome is X-linked recessive**, affecting males more severely. - This statement is incorrect because it implies that autosomal dominant inheritance is the primary or typical mode, which is not true for the majority of cases. *Nerve deafness* - **Sensorineural hearing loss**, particularly for high frequencies, is a common and characteristic extra-renal manifestation of Alport's syndrome. - This symptom typically progresses with age and is a key diagnostic feature. *Glomerulonephritis* - **Progressive glomerulonephritis** is the hallmark renal feature of Alport's syndrome, leading to hematuria, proteinuria, and eventually end-stage renal disease. - It is caused by mutations in collagen type IV genes, which disrupt the integrity of the glomerular basement membrane. *X-linked* - The majority of Alport's syndrome cases (about 85%) are **X-linked recessive**, caused by mutations in the *COL4A5* gene located on the X chromosome. - This explains why males are more severely affected and typically present with earlier onset and more rapid progression of renal disease.

Q: XDR-TB is defined as resistance to which of the following drug combinations?

Fluoroquinolones plus INH plus rifampicin plus amikacin. **Fluoroquinolones plus INH plus rifampicin plus amikacin** - **Extensively drug-resistant tuberculosis (XDR-TB)** is defined by resistance to the most effective anti-TB drugs: **isoniazid (INH)**, **rifampicin**, any **fluoroquinolone**, and at least one of the three injectable second-line drugs (**amikacin**, **kanamycin**, or **capreomycin**). - This combination signifies a substantial therapeutic challenge due to limited treatment options and a high risk of treatment failure. *INH plus rifampicin* - Resistance to **INH** and **rifampicin** defines **multidrug-resistant tuberculosis (MDR-TB)**, which is a precursor to XDR-TB but not XDR-TB itself. - While serious, MDR-TB is not as extensively resistant as XDR-TB, as it doesn't include resistance to fluoroquinolones and second-line injectables. *Fluoroquinolones plus INH plus amikacin* - This combination is incomplete for the definition of XDR-TB because it omits **rifampicin** from the core definition. - XDR-TB specifically requires resistance to both **INH** and **rifampicin** (defining MDR-TB), in addition to resistance to a fluoroquinolone and one of the injectable second-line drugs. *Fluoroquinolones plus rifampicin plus kanamycin* - This combination is also incomplete for the definition of XDR-TB as it omits **isoniazid (INH)**, which is one of the two most crucial first-line drugs that characterize MDR-TB. - XDR-TB builds upon MDR-TB's resistance to both INH and rifampicin.

Q: Which dopamine receptor is known for its inhibitory action in the central nervous system?

Dopamine Receptor D2. ***Dopamine Receptor D2*** - The **D2 receptor** is a member of the D2-like family (D2, D3, D4), which are **G-protein coupled receptors** that inhibit adenylyl cyclase activity. - Its activation typically leads to a **decrease in neuronal excitability** and neurotransmitter release, providing an inhibitory effect in the CNS. *Dopamine Receptor D5* - The **D5 receptor** belongs to the D1-like family (D1, D5), which are **G-protein coupled receptors** that stimulate adenylyl cyclase activity. - Activation of D5 receptors typically leads to **excitatory effects** rather than inhibitory ones in the CNS. *No inhibitory dopamine receptor present* - This statement is incorrect as specific dopamine receptor subtypes, particularly the **D2-like family**, are well-established to exert inhibitory actions in the CNS. - These inhibitory effects are crucial for various physiological processes, including motor control and reward pathways. *Dopamine Receptor D1* - The **D1 receptor** is part of the D1-like family (D1, D5) and is known for its **excitatory effects** in the CNS. - Activation of D1 receptors leads to an **increase in intracellular cAMP** and generally enhances neuronal activity.

Q: In a patient experiencing a stress response, which structure acts as the major central coordinator of the sympathetic nervous system?

Hypothalamus. ***Hypothalamus*** - The **hypothalamus** is the primary subcortical region that integrates stress responses by coordinating the **autonomic nervous system** and the **endocrine system**. - It directly regulates the **sympathetic nervous system** activation during stress through its projections to lower brainstem and spinal cord centers. *Nucleus ambiguus* - This nucleus is primarily involved in the motor control of the **pharynx, larynx, and esophagus**, as well as controlling the **parasympathetic innervation of the heart**. - While part of the autonomic system, it is not the major central coordinator of the sympathetic stress response. *Nucleus tractus solitarius* - The **nucleus tractus solitarius (NTS)** receives visceral sensory input from cranial nerves (e.g., vagus nerve) and plays a role in cardiovascular and respiratory reflexes. - It influences the autonomic nervous system but acts as a relay and integration center for specific reflexes rather than the overall central coordinator of the stress response. *Edinger-Westphal nucleus* - The **Edinger-Westphal nucleus** is a preganglionic parasympathetic nucleus that controls the **pupillary light reflex** and **accommodation (lens focusing)**. - Its function is related to the parasympathetic division but not as the central coordinator of the systemic sympathetic stress response.

Question 1

Which of the following muscles is not attached to the medial border of the scapula?

Accepted Answer

Teres major

Answer

Serratus anterior

Answer

Levator scapulae

Answer

Rhomboid major

Question 2

Which is the first steroid intermediate formed in the conversion of cholesterol to steroid hormones?

Accepted Answer

Pregnenolone

Answer

Glucocorticoid

Answer

Mineralocorticoid

Answer

Estradiol

Question 3

What is the immediate source of energy for cellular processes?

Accepted Answer

ATP

Answer

Cori's cycle

Answer

HMP

Answer

TCA cycle

Question 4

Randomization is done to reduce?

Accepted Answer

Selection bias

Answer

Recall bias

Answer

Berksonian bias

Answer

Reporting bias

Question 5

Which subtype of Acute Myeloid Leukemia (AML) is most commonly associated with gum hypertrophy?

Accepted Answer

Acute Myeloid Leukemia M4

Answer

Acute Myeloid Leukemia M2

Answer

Acute Myeloid Leukemia M3

Answer

Acute Myeloid Leukemia M1

Question 6

Stapedius pulls stapes in which direction?

Accepted Answer

Posterior

Answer

Answer

Superior

Answer

Inferior

Question 7

Which of the following statements about Alport's syndrome is incorrect?

Accepted Answer

Autosomal dominant

Answer

Nerve deafness

Answer

Glomerulonephritis

Answer

X-linked

Question 8

XDR-TB is defined as resistance to which of the following drug combinations?

Accepted Answer

Fluoroquinolones plus INH plus rifampicin plus amikacin

Answer

INH plus rifampicin

Answer

Fluoroquinolones plus INH plus amikacin

Answer

Fluoroquinolones plus rifampicin plus kanamycin

Question 9

Which dopamine receptor is known for its inhibitory action in the central nervous system?

Accepted Answer

Dopamine Receptor D2

Answer

Dopamine Receptor D5

Answer

No inhibitory dopamine receptor present

Answer

Dopamine Receptor D1

Question 10

In a patient experiencing a stress response, which structure acts as the major central coordinator of the sympathetic nervous system?

Accepted Answer

Hypothalamus

Answer

Nucleus ambiguus

Answer

Nucleus tractus solitarius

Answer

Edinger-Westphal nucleus

NEET-PG 2015

Anatomy

Biochemistry

Community Medicine

Dental

ENT

Internal Medicine

Microbiology

Pharmacology

Physiology