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: 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: 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 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: 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: Pyruvate dehydrogenase requires all cofactors except:

Pyridoxin (Vitamin B6). ***Pyridoxin (Vitamin B6)*** - **Pyridoxin** (vitamin B6) is a coenzyme for many enzymes involved in **amino acid metabolism**, but it is **not directly required** by the pyruvate dehydrogenase complex. - The pyruvate dehydrogenase complex uses **thiamine pyrophosphate**, **lipoic acid**, **FAD**, **NAD+**, and **Coenzyme A** as cofactors. *Thiamin* - **Thiamin pyrophosphate** (TPP), derived from thiamin (vitamin B1), is a crucial coenzyme for the **E1 subunit** of the pyruvate dehydrogenase complex. - It participates in the **decarboxylation** of pyruvate, releasing CO2. *Riboflavin* - **FAD** (flavin adenine dinucleotide), derived from riboflavin (vitamin B2), is a coenzyme for the **E3 subunit** (dihydrolipoyl dehydrogenase) of the pyruvate dehydrogenase complex. - It is involved in the **regeneration of oxidized lipoamide**. *Niacin* - **NAD+** (nicotinamide adenine dinucleotide), derived from niacin (vitamin B3), is a coenzyme for the **E3 subunit** of the pyruvate dehydrogenase complex. - It acts as an **electron acceptor** during the reoxidation of FADH2.

Q: Which of the following statements are true regarding the visual cycle cascade?

All of the options are true. ***All of the statements are true*** The visual cycle cascade involves multiple interconnected events in phototransduction: **Light causes isomerization of 11-cis-retinal to all-trans-retinal** - This is the **primary photochemical event** that initiates vision - Light absorption causes the **cis-trans isomerization** in less than a picosecond - This conformational change is the only light-dependent step in the entire cascade **Retinal is involved in the visual cycle** - **11-cis-retinal** serves as the chromophore bound to opsin forming rhodopsin - After isomerization to **all-trans-retinal**, it must be converted back to 11-cis-retinal - This regeneration occurs through the **retinoid cycle** involving RPE cells **Involves a conformational change in opsin** - The isomerization of retinal triggers **conformational changes in opsin** - This converts rhodopsin to **metarhodopsin II** (the active form) - Activated opsin then activates **transducin** (G-protein), amplifying the signal and leading to hyperpolarization of photoreceptor cells All three statements accurately describe essential components of the visual cycle cascade.

Question 1

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 2

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 3

Which vitamin deficiency is associated with night blindness?

Accepted Answer

Vit. A

Answer

Biotin

Answer

Thiamine

Answer

Riboflavin

Question 4

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 5

Dietary deficiency of which vitamin is considered extremely rare?

Accepted Answer

Vitamin E

Answer

Thiamine

Answer

Vitamin B6

Answer

Vitamin D

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

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 8

Which nutrient is lost maximally in polished rice?

Accepted Answer

Thiamine

Answer

Proteins

Answer

Ascorbic acid

Answer

Calcitriol

Question 9

Pyruvate dehydrogenase requires all cofactors except:

Accepted Answer

Pyridoxin (Vitamin B6)

Answer

Thiamin

Answer

Riboflavin

Answer

Niacin

Question 10

Which of the following statements are true regarding the visual cycle cascade?

Accepted Answer

All of the options are true

Answer

Light causes isomerization of 11-cis-retinal to all-trans-retinal

Answer

Retinal is involved in the visual cycle

Answer

Involves a conformational change in opsin

Vitamins and Coenzymes — MCQs

Vitamins and Coenzymes — MCQs

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