Vitamins and Coenzymes Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Vitamins and Coenzymes. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Vitamins and Coenzymes Indian Medical PG Question 1: Which one of the following vitamins given as a supplement during the peri-conceptional period to a woman can help prevent the neural tube defects in the baby ?
- A. Riboflavin
- B. Folic acid (Correct Answer)
- C. Thiamine
- D. Vitamin B12
Vitamins and Coenzymes Explanation: ***Folic acid***
- **Folic acid** (vitamin B9) supplementation is crucial during the **peri-conceptional period** to prevent neural tube defects.
- Adequate folic acid intake helps in the proper development and closure of the **neural tube** in the embryo, which forms the brain and spinal cord.
*Riboflavin*
- **Riboflavin** (vitamin B2) is essential for energy metabolism and cellular growth but has no direct, established role in preventing neural tube defects.
- Deficiency can lead to **ariboflavinosis**, characterized by skin lesions, but not directly linked to neural tube malformations.
*Thiamine*
- **Thiamine** (vitamin B1) is vital for carbohydrate metabolism and nerve function.
- Its deficiency causes **beriberi** and neurological problems in adults, but it does not directly prevent neural tube defects.
*Vitamin B12*
- **Vitamin B12** (cobalamin) is important for DNA synthesis and nerve function, and it works closely with folate.
- While B12 deficiency can lead to megaloblastic anemia and neurological issues, **folic acid** is the primary vitamin for preventing neural tube defects.
Vitamins and Coenzymes Indian Medical PG Question 2: What is the appropriate treatment for megaloblastic anemia with neurological symptoms?
- A. Iron supplementation
- B. Folic acid with Hydroxycobalamin (Correct Answer)
- C. Vitamin B1 supplementation
- D. Folic Acid only
Vitamins and Coenzymes Explanation: Folic acid with Hydroxycobalamin
- Neurological symptoms in megaloblastic anemia strongly suggest vitamin B12 deficiency, as folic acid alone can mask this deficiency and worsen neurological sequelae [3].
- Hydroxycobalamin is the preferred treatment for vitamin B12 deficiency, while folic acid addresses the megaloblastic hematopoiesis.
Iron supplementation
- This is used to treat iron deficiency anemia, which presents with microcytic or normocytic red blood cells, not megaloblastic changes [1].
- Iron supplementation would not address the neurological symptoms or the underlying B12 or folate deficiency.
Vitamin B1 supplementation
- Vitamin B1 (thiamine) deficiency is associated with conditions like beriberi and Wernicke-Korsakoff syndrome, characterized by neurological symptoms, but not megaloblastic anemia [4].
- Supplementation would not correct the underlying hematological abnormality or the specific neurological symptoms of B12 deficiency [4].
Folic Acid only
- While folic acid is essential for DNA synthesis and would improve the hematological parameters of megaloblastic anemia, it does not treat vitamin B12 deficiency [2].
- Giving folic acid alone in the presence of B12 deficiency can lead to a worsening of neurological symptoms as it can correct the anemia but allow the neurological damage to progress [3].
Vitamins and Coenzymes Indian Medical PG Question 3: 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
Vitamins and Coenzymes 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.
Vitamins and Coenzymes Indian Medical PG Question 4: The cofactor vitamin B12 is required for the following conversion:
- A. Dopamine to Norepinephrine
- B. Propionyl CoA to methyl malonyl CoA
- C. Methyl malonyl CoA to succinyl CoA (Correct Answer)
- D. Homocysteine to cysteine
Vitamins and Coenzymes Explanation: ***Methyl malonyl CoA to succinyl CoA***
- **Vitamin B12**, in its active form **adenosylcobalamin**, is a crucial cofactor for the enzyme **methylmalonyl-CoA mutase**, which catalyzes the isomerization of **methylmalonyl-CoA to succinyl-CoA**.
- This conversion is vital for the metabolism of **odd-chain fatty acids** and certain **amino acids**, allowing their entry into the **Krebs cycle**.
*Dopamine to Norepinephrine*
- This conversion is catalyzed by **dopamine beta-hydroxylase**, which requires **vitamin C** (ascorbate) and **copper** as cofactors, not vitamin B12.
- It is a key step in the synthesis of **catecholamines** within the nervous system.
*Propionyl CoA to methyl malonyl CoA*
- This conversion is catalyzed by **propionyl-CoA carboxylase** and requires **biotin** as a cofactor, not vitamin B12.
- This reaction is the first step in the metabolic pathway that leads to succinyl-CoA from odd-chain fatty acids.
*Homocysteine to cysteine*
- This conversion occurs via the **transsulfuration pathway** and requires **vitamin B6** (pyridoxal phosphate) as a cofactor, not vitamin B12.
- The enzymes involved are **cystathionine β-synthase** and **cystathionine γ-lyase**, both B6-dependent.
- Vitamin B12 is involved in the **remethylation** of homocysteine to methionine (not in transsulfuration to cysteine).
Vitamins and Coenzymes Indian Medical PG Question 5: All are cofactors for Dehydrogenase except:
- A. SAM (Correct Answer)
- B. NADP
- C. NAD
- D. FAD
Vitamins and Coenzymes Explanation: ***SAM***
- **S-adenosylmethionine (SAM)** is a cofactor involved in **methyl group transfer reactions**, carried out by enzymes known as methyltransferases.
- Dehydrogenase enzymes catalyze **redox reactions**, typically involving the transfer of hydride ions, and thus do not utilize SAM as a cofactor.
*NADP*
- **Nicotinamide adenine dinucleotide phosphate (NADP)** is a crucial coenzyme for many **dehydrogenase reactions**, particularly in **anabolic pathways** like fatty acid synthesis and the pentose phosphate pathway.
- It acts as an **electron carrier**, accepting or donating hydride ions.
*NAD*
- **Nicotinamide adenine dinucleotide (NAD)** is a highly common coenzyme for numerous **dehydrogenase enzymes**, especially in **catabolic pathways** such as glycolysis, the Krebs cycle, and oxidative phosphorylation.
- It functions as an **electron acceptor** or donor in redox reactions.
*FAD*
- **Flavin adenine dinucleotide (FAD)** is a coenzyme derived from **riboflavin (Vitamin B2)** and is associated with various dehydrogenase enzymes, particularly those involved in **electron transport** and fatty acid oxidation.
- FAD can accept two hydrogen atoms (one hydride and one proton) to become FADH₂.
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