Biochemistry
6 questionsA patient on a maize diet presented with diarrhea, dementia and dermatitis. Which vitamin deficiency is responsible for these features
Which amino acid needs to be supplemented through diet in patient with cystathionine beta synthase deficiency
Corneal Transparency is maintained by which of the following GAGs?
A patient had dinner at 8 PM at night and does his blood sugar test at 7 AM in the morning. What is the major source of glucose at this time?
A 5 year old child was brought to the physician with a history of black urine. There is no history of fever or any other complaints. There is no growth retardation and all the developmental milestones are normal. The child is suspected to have an enzyme defect for metabolism of an aromatic amino acid. What is the enzyme deficient
A patient with tendon xanthomas, Increased LDL and cholesterol. What is the most probable diagnosis?
NEET-PG 2021 - Biochemistry NEET-PG Practice Questions and MCQs
Question 11: A patient on a maize diet presented with diarrhea, dementia and dermatitis. Which vitamin deficiency is responsible for these features
- A. Niacin (Correct Answer)
- B. Riboflavin
- C. Thiamine
- D. Pyridoxine
- E. Cobalamin
Explanation: ***Niacin*** - The classic presentation of **pellagra**, caused by a deficiency of **niacin (Vitamin B3)**, is characterized by the "**3 Ds**": **dermatitis**, **diarrhea**, and **dementia**. In severe cases, a fourth 'D' for death can also occur. - A **maize (corn)** staple diet is a known risk factor for niacin deficiency because maize contains niacin in a bound, non-bioavailable form (niacytin) and is low in tryptophan, a precursor to niacin. *Riboflavin* - **Riboflavin (Vitamin B2)** deficiency leads to **ariboflavinosis**, which can cause **cheilosis**, **angular stomatitis**, **glossitis**, and **seborrheic dermatitis**, but not the constellation of diarrhea, dementia, and dermatitis seen in pellagra. - It does not typically manifest with neurological or gastrointestinal symptoms as severe as those described in the question. *Thiamine* - **Thiamine (Vitamin B1)** deficiency causes **beriberi**, characterized by **neurological (dry beriberi)** or **cardiovascular (wet beriberi)** symptoms. - It can lead to **Wernicke-Korsakoff syndrome** in severe cases, which includes neurological deficits, but not the specific "3 Ds" of pellagra. *Pyridoxine* - **Pyridoxine (Vitamin B6)** deficiency can cause **neurological symptoms** such as **peripheral neuropathy**, **seizures**, and **depression**, as well as **dermatitis** and **glossitis**. - It does not present with the characteristic triad of dermatitis, diarrhea, and dementia seen in pellagra. *Cobalamin* - **Cobalamin (Vitamin B12)** deficiency causes **megaloblastic anemia** and **neurological symptoms** including **subacute combined degeneration** of the spinal cord, **peripheral neuropathy**, and **cognitive changes**. - While it can cause neurological symptoms, it does not present with the classic dermatitis and diarrhea combination seen in pellagra.
Question 12: Which amino acid needs to be supplemented through diet in patient with cystathionine beta synthase deficiency
- A. Tryptophan
- B. Serine
- C. Methionine
- D. Cysteine (Correct Answer)
- E. Tyrosine
Explanation: ***Cysteine*** - In **cystathionine beta synthase (CBS) deficiency**, the conversion of **homocysteine** to **cystathionine** (and subsequently to cysteine) is impaired. - This makes **cysteine** an **essential amino acid** for these patients, requiring dietary supplementation. *Tryptophan* - **Tryptophan** is an **essential amino acid** and a precursor for **serotonin** and **niacin**, but its metabolism is not directly affected by CBS deficiency. - Its supplementation is not specifically indicated for this condition. *Serine* - **Serine** is a **non-essential amino acid** that provides the **carbon skeleton** for the synthesis of cysteine from homocysteine in the presence of CBS. - While important in the pathway, CBS deficiency specifically disrupts the downstream conversion of homocysteine, making **cysteine** the deficient product, not serine. *Methionine* - **Methionine** is an **essential amino acid** that is a precursor to **homocysteine**; in CBS deficiency, homocysteine levels are already elevated due to impaired conversion to cystathionine. - Restricting methionine intake is typically recommended in CBS deficiency to reduce homocysteine accumulation, not supplementing it. *Tyrosine* - **Tyrosine** is a **non-essential amino acid** derived from **phenylalanine** and serves as a precursor for catecholamines and thyroid hormones. - Its metabolism is not affected by CBS deficiency, and supplementation is not indicated for this condition.
Question 13: Corneal Transparency is maintained by which of the following GAGs?
- A. Keratan Sulphate (Correct Answer)
- B. Dermatan Sulphate
- C. Heparan Sulphate
- D. Chondroitin Sulphate
Explanation: ***Keratan Sulphate*** - **Keratan sulfate** is a major glycosaminoglycan (GAG) found in the **cornea**, where its specific highly hydrated structure and arrangement help maintain corneal transparency. - The uniform spacing of collagen fibrils, maintained by keratan sulfate, is crucial for minimizing light scattering and allowing light to pass through the cornea. *Dermatan Sulphate* - **Dermatan sulfate** is primarily found in **skin, blood vessels, and heart valves**, contributing to tissue strength and elasticity. - It plays a significant role in wound healing and cardiovascular function, but not directly in maintaining corneal transparency. *Heparan Sulphate* - **Heparan sulfate** is ubiquitously found on **cell surfaces and in the extracellular matrix**, particularly in the basement membranes. - It is involved in cell adhesion, growth factor binding, and anticoagulant activity, but is not the primary GAG responsible for corneal transparency. *Chondroitin Sulphate* - **Chondroitin sulfate** is abundant in **cartilage, bone, and connective tissues**, providing compressive strength and elasticity. - While present in some ocular tissues, it is not the dominant GAG responsible for the unique transparent properties of the cornea.
Question 14: A patient had dinner at 8 PM at night and does his blood sugar test at 7 AM in the morning. What is the major source of glucose at this time?
- A. Liver Glycogen (Correct Answer)
- B. Muscle Glycogen
- C. Gluconeogenesis
- D. Dietary Carbohydrate
- E. Ketone bodies
Explanation: ***Liver Glycogen*** - After an overnight fast (approximately 11 hours in this scenario), the primary mechanism for maintaining blood glucose levels is the breakdown of **liver glycogen** stores. - The liver is crucial for glucose homeostasis as it can release glucose directly into the bloodstream, a function muscle glycogen cannot perform. *Muscle Glycogen* - **Muscle glycogen** serves as an energy reserve primarily for the muscle itself and cannot be directly released into the bloodstream to maintain blood glucose levels. - It is utilized for physical activity and local energy demands within muscle cells. *Gluconeogenesis* - **Gluconeogenesis**, the synthesis of glucose from non-carbohydrate precursors, becomes increasingly important for glucose production after prolonged fasting (typically *after* liver glycogen stores are depleted). - While it contributes during an overnight fast, **liver glycogenolysis** is the dominant source initially. *Dietary Carbohydrate* - **Dietary carbohydrates** from the previous dinner (8 PM) would have been absorbed and utilized or stored as glycogen much earlier than 7 AM the next morning. - By 7 AM, the direct impact of the previous night's meal on circulating glucose is negligible, having been processed hours before. *Ketone Bodies* - **Ketone bodies** are alternative fuel sources produced during prolonged fasting or starvation, but they are **not glucose**. - While they can be used by tissues (brain, heart, muscle) for energy during extended fasting, they do not contribute to blood glucose levels and are metabolically distinct from glucose.
Question 15: A 5 year old child was brought to the physician with a history of black urine. There is no history of fever or any other complaints. There is no growth retardation and all the developmental milestones are normal. The child is suspected to have an enzyme defect for metabolism of an aromatic amino acid. What is the enzyme deficient
- A. Homogentisate dehydrogenase
- B. Homogentistae oxidase (Correct Answer)
- C. Tyrosine Transaminase
- D. Tryptophan Hydroxylase
- E. Phenylalanine Hydroxylase
Explanation: ***Homogentistae oxidase*** - The presentation of a child with **black urine** (alkaptonuria) in the absence of other symptoms is characteristic of a deficiency in **homogentisate oxidase**. - This enzyme is crucial in the catabolism of **tyrosine**, and its deficiency leads to the accumulation of **homogentisic acid**, which oxidizes upon exposure to air, turning urine black. *Homogentisate dehydrogenase* - This enzyme is not a recognized component of the **tyrosine degradation pathway** in humans. - The correct enzyme involved in the breakdown of **homogentisate** is an oxidase, not a dehydrogenase, in this context. *Tyrosine Transaminase* - A deficiency in **tyrosine transaminase** (tyrosinemia type II) would lead to elevated tyrosine levels and typically presents with symptoms affecting the eyes, skin, and intellectual disability, not primarily black urine. - This condition is characterized by **ocular findings** (corneal ulcers), **skin lesions**, and **neurological symptoms**. *Tryptophan Hydroxylase* - This enzyme is involved in the synthesis of **serotonin** and **melatonin** from tryptophan, a different amino acid pathway. - A deficiency or abnormality in **tryptophan hydroxylase** would not cause black urine but could lead to neurological or mood disorders. *Phenylalanine Hydroxylase* - A deficiency in **phenylalanine hydroxylase** causes **phenylketonuria (PKU)**, which affects phenylalanine metabolism, not tyrosine metabolism directly. - PKU typically presents with **intellectual disability**, **musty odor**, **fair skin**, and **seizures** if untreated, not black urine.
Question 16: A patient with tendon xanthomas, Increased LDL and cholesterol. What is the most probable diagnosis?
- A. Type II Hyperlipoproteinemia (Correct Answer)
- B. Type III Hyperlipoproteinemia
- C. Abetalipoproteinemia
- D. Type I Hyperlipoproteinemia
- E. Type IV Hyperlipoproteinemia
Explanation: ***Type II Hyperlipoproteinemia*** - This type is characterized by significantly **elevated LDL and total cholesterol** due to a defect in LDL receptor function or APOB-100. - **Tendon xanthomas** are a classic physical finding in Type II hyperlipoproteinemia, specifically in familial hypercholesterolemia. *Type III Hyperlipoproteinemia* - This condition involves increased levels of **chylomicron remnants** and **VLDL remnants (IDL)**, leading to elevated cholesterol and triglycerides. - While xanthomas can occur (e.g., **palmar xanthomas**), tendon xanthomas are less typical, and the primary lipid abnormality isn't isolated LDL elevation. *Abetalipoproteinemia* - This is a rare autosomal recessive disorder resulting in the **absence of LDL, VLDL, and chylomicrons** in the blood. - Patients present with **fat malabsorption**, neurologic symptoms, and generally have very low or undetectable cholesterol and triglyceride levels, which is contrary to the clinical presentation. *Type I Hyperlipoproteinemia* - This disorder is characterized by a deficiency of **lipoprotein lipase (LPL)** or its cofactor, APO C-II, leading to extremely high levels of **chylomicrons** and **triglycerides**. - While eruptive xanthomas can be seen, **tendon xanthomas** are not a feature, and the primary abnormality is hypertriglyceridemia, not elevated LDL. *Type IV Hyperlipoproteinemia* - This condition is characterized by **elevated VLDL** and **triglycerides** with normal or slightly elevated LDL. - Xanthomas are generally not a feature, and the primary abnormality is hypertriglyceridemia rather than hypercholesterolemia with elevated LDL.
Internal Medicine
1 questionsA patient presented with dryness in the eye with a gritty sensation along with corneal softening. What is the most probable cause?
NEET-PG 2021 - Internal Medicine NEET-PG Practice Questions and MCQs
Question 11: A patient presented with dryness in the eye with a gritty sensation along with corneal softening. What is the most probable cause?
- A. Follicular conjunctivitis
- B. Vitamin A deficiency (Correct Answer)
- C. Viral Keratitis
- D. Riboflavin Deficiency
Explanation: Vitamin A deficiency - **Dry eyes** with a **gritty sensation (xerophthalmia)** and **corneal softening (keratomalacia)** are classic signs of severe vitamin A deficiency [1], [2]. - This condition can lead to blindness if not treated promptly, as vitamin A is crucial for the health of the **cornea** and **retina** [1], [2]. *Follicular conjunctivitis* - Characterized by the presence of **lymphoid follicles** on the conjunctiva, often due to viral infections like **adenovirus** or **chlamydia**. - While it can cause dryness, it does not typically lead to **corneal softening** or the severe vision-threatening complications seen with vitamin A deficiency. *Viral Keratitis* - Involves inflammation of the **cornea** due to a viral infection, commonly by **herpes simplex virus**. - Symptoms include pain, redness, blurred vision, and sensitivity to light, but **generalized dryness** and **corneal softening** as the primary presentation are less characteristic. *Riboflavin Deficiency* - Also known as **ariboflavinosis**, this deficiency can cause ocular symptoms like **photophobia**, **corneal vascularization**, and **conjunctivitis**. - However, it typically does not present with **severe dry eyes** or **corneal softening (keratomalacia)** as seen in vitamin A deficiency.
OB/GYN
1 questionsAn elderly female presented with dribbling of urine only on coughing and straining. What type of urinary incontinence is she suffering from
NEET-PG 2021 - OB/GYN NEET-PG Practice Questions and MCQs
Question 11: An elderly female presented with dribbling of urine only on coughing and straining. What type of urinary incontinence is she suffering from
- A. Overflow incontinence
- B. Stress incontinence (Correct Answer)
- C. Urge incontinence
- D. Neurogenic bladder
Explanation: ***Stress incontinence*** - **Dribbling of urine** specifically with activities that increase intra-abdominal pressure like **coughing or straining** is the hallmark of stress incontinence. - This type of incontinence results from **weakness of the pelvic floor muscles** and/or intrinsic urethral sphincter deficiency. *Overflow incontinence* - This occurs when the bladder is **overfilled and unable to empty**, leading to constant dribbling or leakage. - Patients typically experience a **poor stream**, hesitancy, and a feeling of incomplete emptying, which are not described here. *Urge incontinence* - Characterized by a **sudden, strong urge to urinate** that is difficult to defer, often leading to involuntary leakage before reaching the toilet. - It is caused by **involuntary contractions of the detrusor muscle** and is not directly related to physical exertion like coughing. *Neurogenic bladder* - This refers to bladder dysfunction due to a **neurological condition** affecting bladder control, such as spinal cord injury or multiple sclerosis. - Symptoms can vary broadly (flaccid or spastic bladder) and are not limited to leakage with coughing alone.
Pathology
1 questionsWhich of the following is associated with defect in mismatch repair
NEET-PG 2021 - Pathology NEET-PG Practice Questions and MCQs
Question 11: Which of the following is associated with defect in mismatch repair
- A. MUTYH Associated Polyposis
- B. Bloom Disorder
- C. SCID
- D. Hereditary HNPCC (Correct Answer)
Explanation: ***Hereditary HNPCC*** - **Hereditary Nonpolyposis Colorectal Cancer (HNPCC)**, also known as Lynch syndrome, is caused by inherited mutations in **DNA mismatch repair (MMR) genes** [1]. - Defective MMR leads to an accumulation of **mutations** in microsatellite regions, increasing the risk of colorectal and other cancers [1]. *MUTYH Associated Polyposis* - This condition is associated with mutations in the **MUTYH gene**, which plays a role in **base excision repair**, not mismatch repair [1]. - It leads to an increased risk of colorectal polyps and cancer, but through a different DNA repair pathway. *Bloom Disorder* - Bloom syndrome is caused by mutations in the **BLM gene**, which encodes a DNA helicase involved in **DNA replication** and repair. - It results in genomic instability, increased cancer risk, and characteristic growth retardation and photosensitivity, distinct from mismatch repair defects. *SCID* - **Severe Combined Immunodeficiency (SCID)** refers to a group of genetic disorders that impair the development and function of **T and B lymphocytes**. - While some forms involve defects in DNA repair enzymes vital for V(D)J recombination (**e.g., RAG enzymes, Artemis**), SCID is primarily an immune disorder and not directly associated with the mismatch repair pathway in the context of cancer predisposition like HNPCC. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, p. 817.
Physiology
1 questionsA young patient presents with muscle spasms, numbness in the hands and feet, seizures, and difficulty in breathing due to laryngospasm. His blood work reveals an electrolyte imbalance. What is the most likely cause of these manifestations?
NEET-PG 2021 - Physiology NEET-PG Practice Questions and MCQs
Question 11: A young patient presents with muscle spasms, numbness in the hands and feet, seizures, and difficulty in breathing due to laryngospasm. His blood work reveals an electrolyte imbalance. What is the most likely cause of these manifestations?
- A. Respiratory Alkalosis (Correct Answer)
- B. Metabolic Alkalosis
- C. Respiratory Acidosis
- D. Metabolic Acidosis
Explanation: ***Respiratory Alkalosis*** - **Hyperventilation** (the likely underlying cause) leads to decreased partial pressure of carbon dioxide (**PCO2**), causing an increase in pH and **respiratory alkalosis**. - This **alkalosis** decreases **ionized calcium** levels by increasing calcium binding to albumin, leading to **hypocalcemia**. - **Hypocalcemia** causes increased neuromuscular excitability, resulting in **muscle spasms, numbness** (paresthesias), **seizures**, and **laryngospasm** (difficulty breathing). - This is the classic presentation of **hypocalcemic tetany** secondary to respiratory alkalosis. *Metabolic Alkalosis* - This imbalance is primarily characterized by an increase in **bicarbonate (HCO3-)** concentration, often due to **vomiting** or diuretic use. - While it can also cause alkalosis leading to **hypocalcemia** and similar neurological symptoms, the acute and severe presentation with prominent tetany and laryngospasm is more characteristic of **respiratory alkalosis**. - Metabolic alkalosis typically has a more gradual onset. *Respiratory Acidosis* - Caused by **hypoventilation**, leading to an increase in **PCO2** and a decrease in pH (acidosis). - **Acidosis increases ionized calcium**, so this would not cause hypocalcemic symptoms. - This condition typically manifests as **somnolence, confusion**, or CNS depression, not the neuromuscular excitability seen in this patient. *Metabolic Acidosis* - Characterized by a decrease in **bicarbonate (HCO3-)** and a decrease in pH, often due to conditions like **diabetic ketoacidosis** or **renal failure**. - **Acidosis increases ionized calcium**, making hypocalcemic tetany unlikely. - Symptoms usually include **Kussmaul breathing** (compensatory hyperventilation) and potential cardiac arrhythmias, which do not match this patient's presentation of tetany and laryngospasm.