NEET-PG 2020 Practice Questions

Q: If the percentage of thymine residues in DNA is 28%. What is the percentage of cytosine?

22%. ***22%*** - According to **Chargaff's rules**, in a DNA molecule, the amount of **adenine (A) is equal to the amount of thymine (T)**, and the amount of **guanine (G) is equal to the amount of cytosine (C)**. - If thymine (T) is 28%, then adenine (A) is also 28%, making a total of 56% for A+T. The remaining 44% (100% - 56%) is split equally between guanine and cytosine, so cytosine (C) is 22%. *36%* - This percentage would be plausible if the sum of adenine and thymine were 28%, which is incorrect as A and T are equal and their sum would thus be 56%. - This value does not adhere to the principle of **base pairing complementarity** and the total percentage of all bases summing to 100%. *44%* - This would be the combined percentage of guanine and cytosine, not the percentage of cytosine alone. - If cytosine were 44%, then guanine would also be 44%, leading to a total of 88% for G+C, which is inconsistent with T being 28%. *28%* - This is the percentage of thymine, and by **Chargaff's rules**, it would also be the percentage of adenine, not cytosine. - Cytosine percentages are derived from the remaining proportion of bases after accounting for adenine and thymine.

Q: A patient complains of knee pain. Routine investigations are unremarkable and still, the patient is unsatisfied. Urine turns black on standing, what is the enzyme involved?

Homogentisate oxidase. ***Homogentisate oxidase*** - **Homogentisate oxidase** deficiency leads to **alkaptonuria**, where homogentisic acid accumulates and is excreted in urine, turning it black upon standing or exposure to air. The knee pain could be due to **ochronosis**, the deposition of oxidized homogentisic acid in cartilage and connective tissues. - The unremarkable routine investigations with persistent knee pain suggest a less common metabolic disorder, which is consistent with **alkaptonuria**'s chronic and insidious presentation. *Methylmalonyl-CoA mutase* - A deficiency in **methylmalonyl-CoA mutase** causes **methylmalonic acidemia**, a metabolic disorder typically presenting in infancy with neurological symptoms, feeding difficulties, and developmental delay. - It does not cause urine to turn black on standing or lead to specific joint pain like that seen in ochronosis. *Xanthine oxidase* - **Xanthine oxidase** is involved in purine metabolism, and its inhibition (e.g., by allopurinol) is used to treat **gout**. - While gout can cause knee pain, it is characterized by elevated uric acid and typically responds to conventional treatments and the urine does not turn black. *Tyrosine hydroxylase* - **Tyrosine hydroxylase** is the rate-limiting enzyme in catecholamine synthesis, converting tyrosine to L-DOPA. - Defects in this enzyme are rare and result in neurological disorders, such as **DOPA-responsive dystonia**, and do not cause urine to blacken or lead to direct joint damage.

Q: Vitamin B12 is found maximum in:

Animal products. ***Animal products*** - **Vitamin B12**, or cobalamin, is primarily synthesized by bacteria and accumulates in animal tissues, making **meat, fish, poultry, eggs, and dairy** the richest dietary sources. - Humans generally cannot synthesize vitamin B12 and must obtain it from dietary sources, with **animal-derived foods** being the most concentrated and bioavailable forms. *Sunlight* - **Sunlight** is primarily critical for the synthesis of **Vitamin D** in the skin, not Vitamin B12. - Exposure to sunlight has no direct role in the production or absorption of **Vitamin B12**. *Green leafy vegetables* - **Green leafy vegetables** are excellent sources of nutrients like **folate, Vitamin K, and iron**, but they are generally devoid of naturally occurring **Vitamin B12**. - While some fortified plant-based foods may contain Vitamin B12, naturally, these vegetables do not provide it. *Roots and tubers* - **Roots and tubers** like potatoes, carrots, and sweet potatoes are good sources of carbohydrates, fiber, and various vitamins and minerals such as **Vitamin C and potassium**. - They do not contain significant amounts of **Vitamin B12**, as they are plant-based foods.

Q: A patient presented with weakness of the right side of the face. There is associated ipsilateral loss of pain and temperature of face and contralateral body. The lesion is most likely located at

Lateral pons. ***Lateral pons*** - A lesion in the **lateral pons** would affect the **facial nerve nucleus** (VII) causing ipsilateral facial weakness. It would also damage the **spinal trigeminal nucleus** (V) leading to ipsilateral facial loss of pain and temperature [1]. - The involvement of the **spinothalamic tract** in the lateral pons would result in contralateral body loss of pain and temperature [1]. *Lateral medulla* - A lesion in the **lateral medulla** (Wallenberg syndrome) typically causes ipsilateral facial sensory loss (due to involvement of the spinal trigeminal nucleus), but would not affect the facial nerve nucleus directly to cause facial weakness [1]. - It also presents with **vertigo, nystagmus, ataxia**, and **dysphagia**, which are not mentioned in the patient's presentation. *Medial pons* - A lesion in the **medial pons** would primarily affect the **corticospinal tract** causing contralateral weakness and the **abducens nerve** (VI) causing ipsilateral gaze palsy, which are not described. - It would not typically involve the facial nerve directly to cause significant facial weakness or the spinal trigeminal nucleus for ipsilateral facial sensory loss. *Medial medulla* - A lesion in the **medial medulla** (Dejerine syndrome) usually affects the **pyramidal tract** causing contralateral hemiparesis and the **hypoglossal nerve** (XII) causing ipsilateral tongue deviation. - It does not explain the ipsilateral facial weakness or the ipsilateral facial loss of pain and temperature.

Q: A female undergoing treatment for infertility with IVF was given Inj. HCG, presented with a history of vomiting, nausea, and headache. The USG is shown as below, what is the diagnosis?

Ovarian Hyperstimulation Syndrome. ***Ovarian Hyperstimulation Syndrome*** - The patient's history of **IVF treatment** with **HCG administration**, combined with symptoms like **nausea**, **vomiting**, and **headache**, strongly suggests **Ovarian Hyperstimulation Syndrome (OHSS)**. - The USG image would likely show enlarged, multicystic ovaries, which is characteristic of OHSS due to an exaggerated response to ovarian stimulation. *Theca lutein Cysts* - While **theca lutein cysts** can be associated with high HCG levels (e.g., in molar pregnancy or multiple gestations), they are usually benign and often asymptomatic, or present with milder symptoms than described. - Unlike OHSS, theca lutein cysts typically do not involve the systemic symptoms of fluid shifts and inflammation seen in this case. *Granulosa cell Tumor* - A **granulosa cell tumor** is a type of ovarian cancer, and while it may present with symptoms related to hormone production (e.g., estrogen), it is not directly caused by IVF treatment or HCG administration. - The clinical presentation of sudden onset symptoms following IVF is not typical for an ovarian neoplasm. *PCOS* - **Polycystic Ovary Syndrome (PCOS)** is a common cause of infertility, but it is a chronic condition characterized by hormonal imbalances, anovulation, and polycystic ovaries. - While patients with PCOS may undergo IVF, the acute symptoms of vomiting, nausea, and headache following HCG administration are not direct manifestations of PCOS itself, but rather a complication of the treatment for infertility.

Q: A radiograph is obtained from a child with scoliosis. What is the name of the angle used to measure spinal curvature?

Cobb's Angle. **Cobb's Angle** - **Cobb's angle** is the primary method for measuring the severity of **scoliosis** on radiographs. - It is measured by drawing lines parallel to the superior endplate of the most tilted superior vertebra and the inferior endplate of the most tilted inferior vertebra of the curve; the angle between these two lines (or their perpendiculars) is the Cobb angle. *Bohler's Angle* - **Bohler's angle** is used in the assessment of **calcaneus fractures** and is measured on a lateral foot radiograph. - A decrease in this angle is indicative of a calcaneal fracture. *Ferguson's Angle* - **Ferguson's angle**, also known as the lumbosacral angle, measures the inclination of the sacrum relative to the horizontal in the standing position. - It is primarily used in the assessment of **spondylolisthesis** and other lumbosacral conditions. *Pauwels' Angle* - **Pauwels' angle** is used to classify **femoral neck fractures** based on the angle of the fracture line relative to the horizontal. - It helps determine the severity and stability of femoral neck fractures, guiding treatment decisions.

Q: A 5-year-old boy has recurrent infections, low platelet count, and rash as shown below. What is the likely diagnosis?

Wiskott Aldrich Syndrome. ***Wiskott Aldrich Syndrome*** - **Wiskott-Aldrich Syndrome (WAS)** is an X-linked recessive disorder characterized by the triad of **thrombocytopenia (low platelets)**, **eczema (rash)**, and **recurrent infections**. - The classic presentation in a young boy with these three features is highly indicative of WAS due to a mutation in the **WAS gene**, which affects immune cell and platelet function. *Bruton's Agammaglobulinemia* - This disorder primarily involves a defect in **B cell development**, leading to a severe deficiency of immunoglobulins and recurrent bacterial infections. - It is not typically associated with **thrombocytopenia** or **eczema** as defining features. *Severe Combined Immunodeficiency* - **SCID** is characterized by a severe defect in both T-cell and B-cell immunity, leading to profound immunodeficiency and recurrent, severe opportunistic infections. - While it causes recurrent infections, it does not typically present with the specific combination of **thrombocytopenia** and **eczema** seen in WAS. *Job Syndrome* - **Job Syndrome (Hyper-IgE Syndrome)** is characterized by very high IgE levels, recurrent skin abscesses, eczema, and coarse facial features. - While **eczema** and **recurrent infections** are present, **thrombocytopenia** is not a characteristic feature of Job Syndrome.

Q: Serum prolactin levels are highest

During third trimester of pregnancy. ***Correct: During third trimester of pregnancy*** - **Serum prolactin levels reach their absolute highest** during the **third trimester of pregnancy**, rising progressively from normal levels (5-25 ng/mL) to peak values of **200-400 ng/mL** near term. - This represents the **highest physiological prolactin levels** observed in humans. - Despite these high levels, **lactation does not occur** during pregnancy because **estrogen and progesterone** block prolactin's action on mammary tissue. - The high prolactin prepares the breast for lactation but milk secretion is inhibited until delivery. *Incorrect: 24 hrs after parturition* - After delivery, prolactin levels actually begin to **decline** from their pregnancy peak, though they remain elevated (around 200 ng/mL). - While **lactogenesis II** (copious milk production) begins 24-72 hours postpartum, this is due to the **removal of estrogen/progesterone inhibition**, not because prolactin levels peak at this time. - The confusion arises from conflating **functional milk production** with **peak hormone levels**. *Incorrect: REM sleep* - Prolactin exhibits **circadian variation** with nocturnal rise during sleep, peaking in early morning hours. - However, these sleep-related peaks (typically 25-40 ng/mL) are **much lower** than pregnancy levels. - This physiological variation is unrelated to reproductive function. *Incorrect: In actively lactating mothers* - During established lactation, basal prolactin levels gradually decline over weeks to months. - Each **suckling episode** causes transient prolactin surges (2-10 fold increase), but these peaks are still **lower than third trimester levels**. - By 6 months postpartum, basal prolactin may return near pre-pregnancy levels despite continued lactation.

Q: Which of the following dependence-causing drugs is most commonly abused worldwide?

Cannabis. ***Cannabis*** - **Cannabis** is the most widely cultivated and consumed illicit drug globally, with the highest prevalence of past-year use. - Its widespread availability, relatively lower perception of harm compared to other drugs, and varied forms of consumption (smoking, edibles) contribute to its extensive abuse. *Heroin* - **Heroin** is a highly addictive opioid that causes severe physical dependence and withdrawal symptoms, but its global prevalence is significantly lower than that of cannabis. - Its high cost, illicit nature, and significant health risks, including overdose, limit its abuse to a smaller, though critically affected, population. *Amphetamine* - **Amphetamines**, including methamphetamine, are potent central nervous system stimulants with a significant abuse potential, leading to psycho-behavioral and physical dependence. - While prevalent in certain regions and among specific populations, their overall global abuse statistics are lower than those for cannabis. *Cocaine* - **Cocaine** is a powerful stimulant derived from the coca plant, known for its strong psychological dependence and significant health consequences. - Its abuse is concentrated in specific geographical areas and demographic groups, making its global prevalence of abuse lower than that of cannabis.

Q: The Figure of 3 sign on chest X-ray is seen in which condition?

Coarctation of the Aorta. ***Coarctation of the Aorta*** - The **Figure of 3 sign** is a classic radiographic finding in coarctation of the aorta, representing pre- and post-stenotic dilatation along with the indentation of the coarctation itself. - This sign is often accompanied by **rib notching** due to collateral circulation, seen on chest X-ray. *Transposition of the Great Arteries* - Characteristically presents with a **"egg-on-a-string" appearance** on chest X-ray due to a narrow mediastinum and cardiomegaly. - This condition involves the great arteries being **switched**, leading to separate systemic and pulmonary circulations. *Mitral Stenosis* - Chest X-ray findings typically include **left atrial enlargement**, which can cause a "double density" sign or splaying of the carina. - Other findings might include **pulmonary venous hypertension** and kerley B lines, not the Figure of 3 sign. *Aortic Stenosis* - Can cause **post-stenotic dilatation of the ascending aorta**, but it does not produce the characteristic Figure of 3 sign. - Severe aortic stenosis might show **left ventricular hypertrophy** on ECG or echocardiography, but not clearly on a standard chest X-ray.

Question 1

If the percentage of thymine residues in DNA is 28%. What is the percentage of cytosine?

Accepted Answer

22%

Answer

36%

Answer

44%

Answer

28%

Question 2

A patient complains of knee pain. Routine investigations are unremarkable and still, the patient is unsatisfied. Urine turns black on standing, what is the enzyme involved?

Accepted Answer

Homogentisate oxidase

Answer

Methylmalonyl-CoA mutase

Answer

Xanthine oxidase

Answer

Tyrosine hydroxylase

Question 3

Vitamin B12 is found maximum in:

Accepted Answer

Animal products

Answer

Sunlight

Answer

Green leafy vegetables

Answer

Roots and tubers

Question 4

A patient presented with weakness of the right side of the face. There is associated ipsilateral loss of pain and temperature of face and contralateral body. The lesion is most likely located at

Accepted Answer

Lateral pons

Answer

Lateral medulla

Answer

Medial pons

Answer

Medial medulla

Question 5

A female undergoing treatment for infertility with IVF was given Inj. HCG, presented with a history of vomiting, nausea, and headache. The USG is shown as below, what is the diagnosis?

Accepted Answer

Ovarian Hyperstimulation Syndrome

Answer

Theca lutein Cysts

Answer

Granulosa cell Tumor

Answer

PCOS

Question 6

A radiograph is obtained from a child with scoliosis. What is the name of the angle used to measure spinal curvature?

Accepted Answer

Cobb's Angle

Answer

Bohler's Angle

Answer

Ferguson's Angle

Answer

Pauwels' Angle

Question 7

A 5-year-old boy has recurrent infections, low platelet count, and rash as shown below. What is the likely diagnosis?

Accepted Answer

Wiskott Aldrich Syndrome

Answer

Bruton's Agammaglobulinemia

Answer

Severe Combined Immunodeficiency

Answer

Job Syndrome

Question 8

Serum prolactin levels are highest

Accepted Answer

During third trimester of pregnancy

Answer

24 hrs after parturition

Answer

REM sleep

Answer

In actively lactating mothers

Question 9

Which of the following dependence-causing drugs is most commonly abused worldwide?

Accepted Answer

Cannabis

Answer

Heroin

Answer

Amphetamine

Answer

Cocaine

Question 10

The Figure of 3 sign on chest X-ray is seen in which condition?

Accepted Answer

Coarctation of the Aorta

Answer

Transposition of the Great Arteries

Answer

Mitral Stenosis

Answer

Aortic Stenosis

NEET-PG 2020

Biochemistry

Internal Medicine

Obstetrics and Gynecology

Orthopaedics

Pediatrics

Physiology

Psychiatry

Radiology