NEET-PG 2015 - Biochemistry Practice Questions

Q: Which of the following is a metabolic disorder inherited in an X-linked manner?

Adrenoleukodystrophy. ***Adrenoleukodystrophy*** - **Adrenoleukodystrophy (ALD)** is an **X-linked recessive disorder** that affects the metabolism of very long-chain fatty acids (VLCFAs). - It leads to the demyelination of nerve cells in the brain and spinal cord, as well as adrenal gland insufficiency. *Phenylketonuria* - **Phenylketonuria (PKU)** is an **autosomal recessive metabolic disorder** caused by a defect in the enzyme phenylalanine hydroxylase. - It results in the accumulation of phenylalanine, leading to intellectual disability if not treated with a specialized diet. *Duchenne muscular dystrophy* - While **Duchenne muscular dystrophy (DMD)** is indeed an **X-linked recessive disorder**, it is primarily a muscle disorder, not a metabolic disorder in the classic sense. - It involves a mutation in the **dystrophin gene**, leading to progressive muscle degeneration and weakness. *Marfan syndrome* - **Marfan syndrome** is an **autosomal dominant disorder** affecting connective tissue. - It is caused by a mutation in the **FBN1 gene**, which codes for fibrillin-1, and primarily affects the skeletal, ocular, and cardiovascular systems.

Q: Which vitamin/nutrient toxicity is associated with excessive sweating?

Choline. ***Choline*** - **Excessive sweating** is a recognized symptom of choline toxicity, often accompanied by a **fishy body odor**, hypotension, and gastrointestinal distress. - Choline plays a role in various metabolic pathways, and high doses can overwhelm these systems, leading to adverse effects. *Biotin* - **Biotin toxicity** is extremely rare, even at very high doses; there are no well-documented cases of adverse effects from excessive intake. - Symptoms like excessive sweating are not associated with biotin overdose. *Folic acid* - While high doses of **folic acid** can mask a **vitamin B12 deficiency**, side effects like gastrointestinal upset or sleep disturbances are rare. - Excessive sweating is **not a characteristic symptom** of folic acid toxicity. *Niacin (Vitamin B3)* - High doses of niacin, especially its nicotinic acid form, are well-known to cause **flushing, itching, and liver toxicity**. - While skin effects are common with niacin toxicity, **excessive sweating** as a primary symptom is not typically reported.

Q: Dermatitis may be a clinical manifestation of deficiency states of all of the following nutrients except -

Thiamine. ***Thiamine*** - A deficiency in **thiamine (vitamin B1)** primarily affects the nervous and cardiovascular systems, leading to conditions like **beriberi**, characterized by neuropathy, heart failure, and Wernicke-Korsakoff syndrome. - Dermatitis is **not a typical or direct clinical manifestation** of thiamine deficiency. *Biotin* - **Biotin (vitamin B7)** deficiency can cause **dermatitis**, often described as a scaly, erythematous rash around the eyes, nose, and mouth. - Hair loss (**alopecia**) and **neurological symptoms** are also associated with biotin deficiency. *Niacin* - **Niacin (vitamin B3)** deficiency leads to **pellagra**, classically presenting with the "3 Ds": **dermatitis**, **diarrhea**, and **dementia**. - The dermatitis in pellagra is typically symmetrical and photosensitive, affecting sun-exposed areas. *Pyridoxine* - **Pyridoxine (vitamin B6)** deficiency can result in **seborrheic dermatitis-like rash**, especially around the eyes, nose, and mouth. - Other symptoms include **glossitis**, **cheilosis**, and **neurological disturbances** like peripheral neuropathy.

Q: Dietary deficiency of which vitamin is considered extremely rare?

Vitamin E. ***Vitamin E*** - **Vitamin E deficiency** is exceptionally rare because it is a **fat-soluble vitamin** stored in the body and is widely available in many common foods. - Symptoms of deficiency, when they do occur, are usually seen in individuals with severe **malabsorption syndromes** or genetic abnormalities affecting its metabolism. *Vitamin B6* - **Vitamin B6 deficiency** can occur, especially in individuals with **alcoholism**, those taking certain medications, or with certain chronic diseases. - It can manifest with neurological symptoms, such as **neuropathy** and **seizures**, as well as dermatological issues. *Thiamine* - **Thiamine (Vitamin B1) deficiency** is a known problem in regions with poor nutrition and in chronic alcoholics. - It leads to conditions like **beriberi** (wet and dry) and **Wernicke-Korsakoff syndrome**, affecting the cardiovascular and nervous systems. *Vitamin D* - **Vitamin D deficiency** is common globally, particularly in populations with limited sun exposure or inadequate dietary intake. - It can cause **rickets** in children and **osteomalacia** in adults, impacting bone health.

Q: Which of these is not a part of extracellular matrix:

Integrins. ***Integrins*** - Integrins are **transmembrane receptors** on the cell surface that facilitate cell-extracellular matrix (ECM) adhesion and cell-cell adhesion. - They are part of the cell membrane, **not** an extracellular component. *Laminin* - **Laminin** is a major protein component of the **basal lamina**, a specialized extracellular matrix that underlies epithelial cells. - It plays a crucial role in cell adhesion, differentiation, and migration within the ECM. *Fibronectin* - **Fibronectin** is a large glycoprotein present in the **extracellular matrix** and in soluble form in blood plasma. - It mediates cell adhesion to the ECM by binding to integrins and various ECM components like collagen and proteoglycans. *Collagen* - **Collagen** is the most abundant protein in the human body and a primary structural component of the **extracellular matrix**. - It provides tensile strength and structural integrity to tissues like skin, bone, tendons, and cartilage.

Q: Which of the following is NOT a manifestation of vitamin E deficiency?

Autonomic dysfunction. ***Autonomic dysfunction*** - **Autonomic dysfunction** is not typically associated with vitamin E deficiency. Instead, it is commonly seen in conditions like **diabetes mellitus**, Parkinson's disease, or certain inherited neuropathies. - Vitamin E primarily acts as an **antioxidant** and is crucial for neurological and red blood cell health. *Hemolytic anemia* - Vitamin E is an **antioxidant** that protects red blood cell membranes from **oxidative damage**. - Its deficiency can lead to increased fragility and **hemolysis** of red blood cells, resulting in hemolytic anemia, particularly in premature infants. *Posterior column abnormalities* - Vitamin E deficiency can cause **neurological dysfunction** due to oxidative damage to neuronal membranes. - This often manifests as degeneration of the **posterior columns** of the spinal cord, leading to impaired proprioception and vibratory sensation. *Cerebellar ataxia* - The **cerebellum** is highly susceptible to oxidative stress, and vitamin E deficiency can lead to damage in this area. - This damage results in **ataxia**, characterized by impaired coordination, balance, and gait disturbances.

Q: APAF-1 is involved in the activation of which of the following caspases?

Caspase 9. ***Caspase 9*** - **APAF-1** (Apoptotic Protease Activating Factor-1) is a key component of the **apoptosome**, which is formed in response to intrinsic apoptotic signals. - The apoptosome recruits and activates **pro-caspase 9**, leading to its proteolytic cleavage and activation into **caspase 9**. *Caspase 8* - **Caspase 8** is primarily involved in the **extrinsic apoptotic pathway**, activated by cell surface death receptors and DISC (Death-Inducing Signaling Complex) formation. - It is not directly activated by APAF-1, which is specific to the intrinsic pathway. *Caspase 10* - **Caspase 10** is also an initiator caspase often associated with the **extrinsic apoptotic pathway**, similar to caspase 8. - Its activation typically occurs within the DISC and not through the apoptosome complex involving APAF-1. *Caspase 3* - **Caspase 3** is an **effector caspase** that is activated by upstream initiator caspases (like caspase 9 or caspase 8) in both intrinsic and extrinsic apoptotic pathways. - While it's a crucial caspase in apoptosis, it is too far downstream and not directly activated by APAF-1; APAF-1 activates caspase 9, which then activates caspase 3.

Q: Spectroscopy primarily studies the interaction between _____ and matter.

Electromagnetic radiation. ***Electromagnetic radiation*** - **Spectroscopy** is the study of the interaction between **matter** and **electromagnetic radiation**, which includes a range from radio waves to gamma rays. - This interaction provides information about the **structure, composition, and physical properties** of matter. *Alpha particles* - **Alpha particles** are composed of two protons and two neutrons, essentially a helium nucleus. - While they interact with matter, their study is more characteristic of **nuclear physics** and **radioactivity**, not the primary focus of spectroscopy. *Protons* - **Protons** are subatomic particles with a positive charge found in the nucleus of an atom. - Their interaction with matter is studied in various fields, but spectroscopy primarily uses **electromagnetic radiation** to probe atomic and molecular energy levels. *Positrons* - **Positrons** are the antimatter counterparts of electrons, having a positive charge. - Their interaction with matter leads to **annihilation events** producing gamma rays, which is fundamental to techniques like Positron Emission Tomography (**PET**), but not the broad field of spectroscopy.

Question 1

Which of the following is a metabolic disorder inherited in an X-linked manner?

Accepted Answer

Adrenoleukodystrophy

Answer

Duchenne muscular dystrophy

Answer

Phenylketonuria

Answer

Marfan syndrome

Question 2

Which vitamin/nutrient toxicity is associated with excessive sweating?

Accepted Answer

Choline

Answer

Biotin

Answer

Folic acid

Answer

Niacin (Vitamin B3)

Question 3

Dermatitis may be a clinical manifestation of deficiency states of all of the following nutrients except -

Accepted Answer

Thiamine

Answer

Biotin

Answer

Niacin

Answer

Pyridoxine

Question 4

Dietary deficiency of which vitamin is considered extremely rare?

Accepted Answer

Vitamin E

Answer

Thiamine

Answer

Vitamin B6

Answer

Vitamin D

Question 5

Which of these is not a part of extracellular matrix:

Accepted Answer

Integrins

Answer

Collagen

Answer

Laminin

Answer

Fibronectin

Question 6

Which of the following is NOT a manifestation of vitamin E deficiency?

Accepted Answer

Autonomic dysfunction

Answer

Posterior column abnormalities

Answer

Cerebellar ataxia

Answer

Hemolytic anemia

Question 7

APAF-1 is involved in the activation of which of the following caspases?

Accepted Answer

Caspase 9

Answer

Caspase 8

Answer

Caspase 10

Answer

Caspase 3

Question 8

Spectroscopy primarily studies the interaction between _____ and matter.

Accepted Answer

Electromagnetic radiation

Answer

Alpha particles

Answer

Protons

Answer

Positrons

NEET-PG 2015 — Biochemistry