Vitamins and Coenzymes Practice Questions

Q: A 25-year-old alcoholic presented with edema, hypertension, ocular disturbance, and changes in mental state. A diagnosis of high output cardiac failure was made with Wet Beri Beri. This condition is due to a deficiency of which vitamin?

Vitamin B1. Vitamin B1 - The constellation of **edema**, **hypertension**, **ocular disturbances**, and **mental status changes** in an **alcoholic** patient with **high-output cardiac failure** (Wet Beri Beri) is a classic presentation of **thiamine (Vitamin B1) deficiency** [2], [3]. - **Thiamine** is crucial for **carbohydrate metabolism** and **neurological function**, and a deficiency can lead to severe cardiovascular and neurological dysfunction, especially in chronic alcoholics due to poor absorption and increased metabolic demand [1], [3]. Vitamin B3 - Deficiency of Vitamin B3 (niacin) causes **pellagra**, characterized by the "4 D's": **dermatitis**, **diarrhea**, **dementia**, and death. - While it can cause psychiatric symptoms (dementia), it does not directly lead to the specific cardiovascular manifestations of high-output cardiac failure as seen in Wet Beri Beri. Vitamin B6 - Deficiency of Vitamin B6 (pyridoxine) can result in **peripheral neuropathy**, **anemia**, and **seizures**. - It is not directly linked to the cardiac and edematous symptoms characteristic of Wet Beri Beri. Vitamin B9 - Deficiency of Vitamin B9 (folate) primarily causes **megaloblastic anemia** and can lead to **neural tube defects** in developing fetuses. - While it can manifest with fatigue and weakness due to anemia, it does not typically present with the acute cardiovascular and neurological syndrome described.

Q: Which vitamin deficiency is associated with night blindness?

Vit. A. ***Vitamin A*** - **Vitamin A deficiency is THE classic cause of night blindness (nyctalopia)**, one of the earliest signs of deficiency - Vitamin A is essential for synthesis of **rhodopsin**, the photopigment in retinal rod cells responsible for vision in dim light - Deficiency leads to impaired dark adaptation and progressive loss of night vision - Other manifestations include **xerophthalmia, Bitot's spots, and keratomalacia** - This is a high-yield fact for NEET-PG examinations *Riboflavin (Vitamin B2)* - Riboflavin deficiency causes **oral-ocular-genital syndrome** - Clinical features include **angular stomatitis, cheilosis, glossitis, seborrheic dermatitis** - Eye manifestations include **corneal vascularization and photophobia**, NOT night blindness - Does NOT cause night blindness as a primary symptom *Thiamine (Vitamin B1)* - Thiamine deficiency causes **Beriberi** (wet and dry forms) and **Wernicke-Korsakoff syndrome** - Characterized by peripheral neuropathy, cardiac dysfunction, and CNS manifestations - Does NOT cause night blindness *Biotin (Vitamin B7)* - Biotin deficiency is rare and causes **dermatitis, alopecia, conjunctivitis** - Also causes neurological symptoms in severe deficiency - Does NOT cause night blindness

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: 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: 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: 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 nutrient is lost maximally in polished rice?

Thiamine. ***Thiamine*** - **Polishing rice** removes the outer layers (bran and germ), which are rich in **thiamine (vitamin B1)**. - Significant loss of thiamine can lead to **beriberi**, characterized by neurological and cardiovascular symptoms. *Proteins* - While some protein is lost during milling, the primary nutritional loss in polished rice is not protein. - The germ and aleurone layer contain some protein, but the main carbohydrate-rich endosperm remains. *Ascorbic acid* - **Ascorbic acid (Vitamin C)** is not a significant nutrient in rice, so its loss during polishing is negligible. - Rice is not a primary dietary source of vitamin C. *Calcitriol* - **Calcitriol** is the active form of **vitamin D**, and rice does not naturally contain vitamin D. - Therefore, it cannot be lost during the polishing process.

Q: Pyridoxine is required in -

Transamination. ***Transamination*** - **Pyridoxal phosphate (PLP)**, the active form of pyridoxine (vitamin B6), is an essential **coenzyme for aminotransferases (transaminases)** - Transamination reactions involve the transfer of an **amino group** from an amino acid to a keto acid, which is crucial for amino acid metabolism - This is the classic biochemical function of vitamin B6 and a frequently tested concept *Glycolysis* - Glycolysis is a metabolic pathway that breaks down glucose into pyruvate - Key cofactors for glycolysis include **NAD+ and ATP**, not vitamin B6 - Does not require pyridoxine as a coenzyme *TCA cycle* - The **TCA cycle (Krebs cycle)** is a central metabolic pathway for energy production - Uses enzymes that require cofactors such as **NAD+, FAD, and Coenzyme A** (derived from pantothenic acid) - Pyridoxine is not directly involved as a coenzyme in TCA cycle reactions *Glycogenesis* - Glycogenesis is the process of synthesizing **glycogen from glucose** - Primarily involves enzymes like **glycogen synthase** and **branching enzyme** - Requires **UTP and glucose-1-phosphate**, not pyridoxine

Q: In the context of energy metabolism, which coenzyme is niacin a precursor to?

NAD. ***NAD*** - Niacin (vitamin B3) is a direct precursor to **nicotinamide adenine dinucleotide (NAD/NAD+)**. - NAD is the crucial coenzyme in **energy metabolism**, primarily involved in **catabolic pathways** such as glycolysis, TCA cycle, and electron transport chain. - Functions as an **electron carrier** in redox reactions, accepting electrons during oxidation of fuel molecules. *Thiamine pyrophosphate (TPP)* - **Thiamine (vitamin B1)** is the precursor to TPP, not niacin. - TPP plays a vital role in **carbohydrate metabolism**, particularly in pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase complexes. *NADP* - While niacin is also a precursor to **NADP/NADPH**, this coenzyme is primarily used in **anabolic (biosynthetic) pathways**, not energy metabolism. - NADP functions in reductive biosynthesis (fatty acid synthesis, cholesterol synthesis) and **oxidative stress protection** via the pentose phosphate pathway. - The question specifically asks about **energy metabolism**, making NAD the correct answer as it participates in catabolic, energy-producing reactions. *Flavin adenine dinucleotide (FAD)* - **Riboflavin (vitamin B2)** is the precursor to FAD, not niacin. - FAD is a coenzyme involved in various metabolic reactions, especially in the **TCA cycle** and **electron transport chain**, acting as an electron acceptor.

Question 1

A 25-year-old alcoholic presented with edema, hypertension, ocular disturbance, and changes in mental state. A diagnosis of high output cardiac failure was made with Wet Beri Beri. This condition is due to a deficiency of which vitamin?

Accepted Answer

Vitamin B1

Answer

Vitamin B3

Answer

Vitamin B6

Answer

Vitamin B9

Question 2

Which vitamin deficiency is associated with night blindness?

Accepted Answer

Vit. A

Answer

Biotin

Answer

Thiamine

Answer

Riboflavin

Question 3

Which of the following statements about vitamin K is correct?

Accepted Answer

Prolonged use of antimicrobials can lead to vitamin K deficiency.

Answer

All of the options are incorrect.

Answer

It is an anticoagulant.

Answer

The recommended dietary allowance (RDA) for adults is 500-600 micrograms.

Question 4

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 5

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 6

Which vitamin/nutrient toxicity is associated with excessive sweating?

Accepted Answer

Choline

Answer

Biotin

Answer

Folic acid

Answer

Niacin (Vitamin B3)

Question 7

Dietary deficiency of which vitamin is considered extremely rare?

Accepted Answer

Vitamin E

Answer

Thiamine

Answer

Vitamin B6

Answer

Vitamin D

Question 8

Which nutrient is lost maximally in polished rice?

Accepted Answer

Thiamine

Answer

Proteins

Answer

Ascorbic acid

Answer

Calcitriol

Question 9

Pyridoxine is required in -

Accepted Answer

Transamination

Answer

Glycolysis

Answer

TCA cycle

Answer

Glycogenesis

Question 10

In the context of energy metabolism, which coenzyme is niacin a precursor to?

Accepted Answer

NAD

Answer

Thiamine pyrophosphate (TPP)

Answer

NADP

Answer

Flavin adenine dinucleotide (FAD)

Vitamins and Coenzymes — MCQs

Vitamins and Coenzymes — MCQs

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