Block 6 GI Vitam & Mineral MCQ's
Questions and Answers
- 1.
Which of the following is true of the vitamin niacin? It:
- A.
Functions primarily in the form of thiamin pyrophosphate.
- B.
Is converted to the coenzymes FAD and FMN.
- C.
Can be synthesized from tryptophan
- D.
Is an essential component of coenzyme A
- E.
Is the prosthetic group for a number of carboxylation reactions
Correct Answer
C. Can be synthesized from tryptopHanExplanation
Hartnup’s disease is a hereditary nutritional disorder resulting in niacin deficiency. It is due to a deficit in the intestines and kidneys, making it difficult for the body to break down and absorb dietary tryptophan. The resulting condition is similar to pellagra, including symptoms of red, scaly rash, and sensitivity to sunlight. Oral niacin is given as a treatment for this condition in doses ranging from 40–200 mg, with a good prognosis if identified and treated early. Niacin synthesis is also deficient in carcinoid syndrome, because of metabolic diversion of its precursor tryptophan to form serotonin.Rate this question:
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- 2.
Which vitamin participates as a coenzyme in the carboxylation of Acetyl-CoA to malonyl-CoA?
- A.
Niacin
- B.
Riboflavin
- C.
Thiamin
- D.
Pyridoxine
- E.
Biotin
Correct Answer
E. BiotinExplanation
Biotin is the correct answer because it is a vitamin that acts as a coenzyme in the carboxylation of Acetyl-CoA to malonyl-CoA. Biotin is involved in various carboxylation reactions in the body, including the synthesis of fatty acids. It helps in the transfer of carbon dioxide during the carboxylation process, which is essential for the production of malonyl-CoA. Therefore, biotin plays a crucial role in fatty acid synthesis and energy production.Rate this question:
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- 3.
The DRI of Vitamin A for an 18a old I is: EAR 625pg/d, RDA 900pg/d and UL 2800pg/d. A patient of that group taking on average 950pg/d will suffer from symptoms of
- A.
Poisoning with a probability of about 50%.
- B.
Poisoning with a probability of about 2%.
- C.
Deficiency with a probability of about 2%.
- D.
Deficiency with a probability of about 98%.
- E.
Deficiency with a probability of about 50%.
Correct Answer
C. Deficiency with a probability of about 2%.Explanation
Based on the given information, the patient is taking on average 950pg/d of Vitamin A, which is above the EAR (Estimated Average Requirement) of 625pg/d. This means that the patient is likely to meet their daily requirement for Vitamin A and avoid deficiency symptoms. Since the patient's intake is below the RDA (Recommended Daily Allowance) of 900pg/d, there is a small probability (about 2%) that the patient may still experience some deficiency symptoms, but it is unlikely. Therefore, the correct answer is "deficiency with a probability of about 2%."Rate this question:
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- 4.
In 1860 the explorers Burke, Gray, King and Wills star1ed on an expedition to cross Australia for the first time in South-North direction. On their return journey they ran short of food and had to supplement their diet with local fresh-water mussels (Velesunio ambiguus). After a few weeks on this diet they fell ill. They were suffering from a weakness which made it difficult and painful to get up or walk, tachycardia, confusion, convulsions, vomiting, emaciation. Gray, Burke and Wills died, the only survivor, King, never recovered from a peripheral neuropathy. The explorers were suffering from
- A.
Beri-beri
- B.
Pellagra
- C.
Scurvy
- D.
Rickets
- E.
Pernicious anemia
Correct Answer
A. Beri-beriExplanation
Its symptoms include weight loss, emotional disturbances, impaired sensory perception (Wernicke's encephalopathy), weakness and pain in the limbs, and periods of irregular heart rate. Edema (swelling of bodily tissues) is common. It may increase the amount of lactic acid and pyruvic acid within the blood. In advanced cases, the disease may cause heart failure and death.Rate this question:
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- 5.
A 47a old male comes to the emergency room with bleeding gums, hemarthrosis (blood collection) in the right knee, and hematemesis (vomiting blood). He is homeless, admits being drunk at least 5 times a week. His diet mainly consists of leftovers from fast food restaurants. Medical history: Food poisoning treated with ampicillin 2 weeks ago. Physical exam: emaciated, with poor hygiene, ecchymosis (large patches of bleeding into skin). Lab: Hb 9.7mg/d1. Normal platelet count, fibrinogen and thrombin time. PT and PTT prolonged. The patient needs supplementation with
- A.
Vitamin A
- B.
Vitamin K
- C.
Vitamin C
- D.
Copper
- E.
Iron
Correct Answer
B. Vitamin KExplanation
The patient's presentation is consistent with a bleeding disorder, as evidenced by bleeding gums, hemarthrosis, and hematemesis. The history of alcohol abuse and poor diet suggests malnutrition, which can lead to vitamin deficiencies. The prolonged PT and PTT indicate impaired clotting factors, which are dependent on vitamin K for their synthesis. Therefore, the patient needs supplementation with vitamin K to correct the clotting abnormalities and manage the bleeding.Rate this question:
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- 6.
Your patient is a 5a old girl, X.Y., brought by her mother into your family practice because of itchy and scaly skin. The child also complains about constant headaches and nausea, chronic fatigue and bone pain. PE reveals patches of alopecia and a moderately enlarged liver. X-ray shows bone demineralization and premature closure of epiphyses. Upon questioning the mother states that as her daughter was not putting on weight she has been giving her cod liver oil 3 times a day for the past 9mo. The most likely diagnosis is
- A.
Vitamin A poisoning
- B.
Vitamin A deficiency
- C.
Vitamin K poisoning
- D.
Vitamin K deficiency
- E.
Vitamin D deficiency
Correct Answer
A. Vitamin A poisoningExplanation
The symptoms and findings described in the scenario are consistent with vitamin A poisoning. Excessive intake of vitamin A, such as through excessive consumption of cod liver oil, can lead to symptoms such as itchy and scaly skin, headaches, nausea, fatigue, bone pain, alopecia, and liver enlargement. The X-ray findings of bone demineralization and premature closure of epiphyses further support this diagnosis. Vitamin A deficiency would not explain these symptoms, and the other options (vitamin K poisoning, vitamin K deficiency, and vitamin D deficiency) are not supported by the clinical presentation.Rate this question:
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- 7.
You are working in an inner-city polyclinic run by a charity. One of your patient is A. B., a 18mo old boy brought in by his mother (17-year old single parent) because of poor growth, delayed development of dentition and general weakness. Physical exam reveals bowing of legs, soft occipital and parietal bones with elastic recoil and enlargement of costochondral junctions. Serum analysis demonstrates reduced calcium and phosphate concentrations. Upon questioning the mother states that as she cannot afford much meats and dairy products, the boy is fed mainly with starchy vegetables. Because of the insecure neighborhood the boy spends most of his time indoors. The boy needs supplementation with
- A.
Vitamin A
- B.
Vitamin B complex
- C.
Vitamin C
- D.
Vitamin D
- E.
Vitamin E
Correct Answer
D. Vitamin DExplanation
The patient in this scenario is presenting with signs and symptoms of rickets, which is caused by a deficiency in vitamin D. The bowing of legs, soft occipital and parietal bones, and enlargement of costochondral junctions are all characteristic findings of rickets. Additionally, the child's diet, which consists mainly of starchy vegetables, is likely lacking in vitamin D-rich foods such as meats and dairy products. Furthermore, the fact that the child spends most of his time indoors suggests limited sun exposure, which is another source of vitamin D. Therefore, the patient requires supplementation with vitamin D to address the deficiency and improve his growth and development.Rate this question:
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- 8.
Pernicious anemia in an elderly patient is most often due to:
- A.
Lack of intrinsic factor
- B.
Lack of folate in the diet
- C.
Lack of thiamin in the diet
- D.
Deficiency in methionine
- E.
Lack of B12 in the diet
Correct Answer
A. Lack of intrinsic factorExplanation
Pernicious anemia in an elderly patient is most often due to a lack of intrinsic factor. Intrinsic factor is a protein produced in the stomach that is necessary for the absorption of vitamin B12. Without intrinsic factor, vitamin B12 cannot be properly absorbed from the diet, leading to a deficiency and subsequent anemia. This type of anemia is more common in older individuals due to age-related changes in the stomach lining, which can impair intrinsic factor production.Rate this question:
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- 9.
Thiamin deficiency, which is common in alcoholics, slows the TCA cycle by decreasing the activity of a-ketoglutarate dehydrogenase. This deficiency also decreases the activity of another mitochondrial enzyme resulting in the build- up of pyruvate and a resulting lactic acidosis. The enzyme is:
- A.
Pyruvate carboxylase
- B.
Pyruvate kinase
- C.
Citrate synthetase
- D.
Pyruvate dehydrogenase
- E.
Pyruvate decarboxylase
Correct Answer
D. Pyruvate dehydrogenaseExplanation
Thiamin deficiency in alcoholics slows down the TCA cycle by reducing the activity of a-ketoglutarate dehydrogenase. This deficiency also decreases the activity of pyruvate dehydrogenase, another mitochondrial enzyme. As a result, pyruvate accumulates and leads to lactic acidosis. Therefore, the correct answer is Pyruvate dehydrogenase.Rate this question:
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- 10.
The Food and Drug Administration recommends that food be fortified with folic acid to reduce the incidence of birth defects such as spina bifida. A folic acid derivative is required for which of the following eukaryotic processes?
- A.
Carboxylation of acetyl CoA to malonyl CoA
- B.
Activation of methionine to form S-adenosylmethionine
- C.
Absorption and uptake of vitamin B12
- D.
Transamination reactions of amino acids.
- E.
Thymidine synthesis
Correct Answer
E. Thymidine synthesisExplanation
The correct answer is thymidine synthesis. Folic acid is required for the synthesis of thymidine, which is an essential component of DNA. Thymidine synthesis is crucial for cell division and growth, including the development of a fetus during pregnancy. By fortifying food with folic acid, the incidence of birth defects such as spina bifida can be reduced, as folic acid ensures an adequate supply of thymidine for proper DNA synthesis and cell division.Rate this question:
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- 11.
Cecelia is a 45 year - old woman, who has received long term oral antibiotic therapy for a severe infection. As a result, she presents with an elevated prothrombin time (PT). Based on this history, what vitamin deficiency is the most likely cause of the elevated PT?
- A.
Thiamin deficiency
- B.
Vitamin B12
- C.
Vitamin C
- D.
Vitamin K
- E.
Vitamin A
Correct Answer
D. Vitamin KExplanation
The most likely cause of the elevated PT in Cecelia is a deficiency in Vitamin K. Vitamin K is essential for the synthesis of clotting factors in the liver, including prothrombin. Long-term oral antibiotic therapy can disrupt the gut microbiota, which is responsible for producing Vitamin K. This disruption can lead to a deficiency in Vitamin K, resulting in an elevated PT. Thiamin deficiency, Vitamin B12 deficiency, Vitamin C deficiency, and Vitamin A deficiency do not directly affect the synthesis of clotting factors, making them less likely causes of the elevated PT in this case.Rate this question:
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- 12.
Lawrence is a 75 year - old man, who had a partial gastrectomy 15 years ago. He now presents with tingling and loss of sensation in his legs, and other signs of peripheral neuropathy Biochemical tests reveal a megaloblastic anemia. Based on his history, his symptoms are most likely secondary to malabsorption of which of the following vitamins?
- A.
B12
- B.
Folate
- C.
Vitamin C
- D.
Vitamin A
- E.
Vitamin K
Correct Answer
A. B12Explanation
Lawrence's symptoms of tingling and loss of sensation in his legs, along with megaloblastic anemia, are indicative of peripheral neuropathy and are most likely caused by a deficiency in vitamin B12. This is because a partial gastrectomy can lead to malabsorption of vitamin B12, as it is primarily absorbed in the stomach. Folate deficiency can also cause megaloblastic anemia, but it does not typically cause peripheral neuropathy. Vitamin C, A, and K deficiencies do not cause megaloblastic anemia or peripheral neuropathy.Rate this question:
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- 13.
Joseph is a 55 year old man with pellagra, characterized by dementia, diarrhea and dermatitis. Which of the following vitamin deficiencies result in pellagra?
- A.
Riboflavin
- B.
Niacin
- C.
Vitamin K
- D.
Vitamin B12
- E.
Vitamin E
Correct Answer
B. NiacinExplanation
Pellagra is a vitamin deficiency disease most commonly caused by a chronic lack of niacin (vitamin B3) in the diet. It can be caused by decreased intake of niacin or tryptophan, and possibly by excessive intake of leucine. It may also result from alterations in protein metabolism in disorders such as carcinoid syndrome. A deficiency of the amino acid lysine can lead to a deficiency of niacin as wellRate this question:
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- 14.
Tim is s 52 year old man with a long-standing history of alcohol abuse, who comes to see his primary care physician because he has been losing balance lately. His wife related to the doctor that his memory is getting worse. Based on the patient's report what is the most likely Vitamin or mineral deficiency that would explain these symptoms?
- A.
Vitamin D
- B.
Calcium
- C.
Vitamin A
- D.
Vitamin C
- E.
Thiamine
Correct Answer
E. ThiamineExplanation
Thiamine deficiency, also known as vitamin B1 deficiency, is the most likely explanation for Tim's symptoms. Thiamine is essential for proper brain function and nerve conduction. Chronic alcohol abuse can lead to thiamine deficiency due to poor dietary intake and impaired absorption. Symptoms of thiamine deficiency include balance problems, memory impairment, and cognitive decline. Therefore, considering Tim's history of alcohol abuse and the reported symptoms, thiamine deficiency is the most likely cause.Rate this question:
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- 15.
When vitamin B12 is deficient, pernicious anemia results from the:
- A.
Lack of N5, N10-methylenetetrahydrofolate
- B.
Accumulation of S-adenosylmethionine
- C.
Lack of methionine
- D.
Lack of 5-adenosylmethionine
- E.
Accumulation of homocysteine
Correct Answer
A. Lack of N5, N10-methylenetetrahydrofolate -
- 16.
The synthesis of a number of neurotransmitters involves decarboxylation of amino acids. The enzymes that carry out these reactions often utilize which of the following cofactors?
- A.
Biotin
- B.
Thiamine
- C.
Tetrahydrofolate
- D.
Vitamin K
- E.
Pyridoxal phosphate
Correct Answer
E. Pyridoxal pHospHateExplanation
Pyridoxal-phosphate (PLP, pyridoxal-5'-phosphate, P5P) is a prosthetic group of some enzymes. It is the active form of vitamin B6, which comprises three natural organic compounds, pyridoxal, pyridoxamine and pyridoxine. PLP plays a role in the conversion of dopa into dopamine, allows the conversion of the excitatory neurotransmitter glutamate to the inhibitory neurotransmitter GABA, and allows SAM to be decarboxylated to form propylamine, which is a precursor to polyamines.Rate this question:
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- 17.
A 75 year old man who presents to the Harlsbro Medical Center with significant peripheral neuropathy. His past medical history is significant for total gastrectomy, performed when he was in his forties, after which he was never placed on vitamin supplements. He rarely drinks alcohol. Mr. Jones' neuropathy is most likely secondary to absorption of which of the following vitamins?
- A.
Folate
- B.
Vitamin A
- C.
Pyridoxine (B6)
- D.
Vitamin B12
Correct Answer
D. Vitamin B12Explanation
The correct answer is Vitamin B12. The patient's significant peripheral neuropathy is likely due to the absorption issue of Vitamin B12. This is supported by the patient's history of total gastrectomy, which can lead to malabsorption of this vitamin. Vitamin B12 deficiency can result in peripheral neuropathy, as it plays a crucial role in maintaining the health of the nerves.Rate this question:
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- 18.
In the absorption of vitamins and minerals, the rule is that water-soluble vitamins do not need pre-absorption chemical digestion, but do need specific apical transporters for absorption, and vice versa for fat soluble vitamins. What one vitamin is the exception to this rule?
- A.
Cobalamin
- B.
Vitamin D
- C.
Vitamin A
- D.
Folate
- E.
Vitamin K
- F.
Niacin
Correct Answer
D. FolateExplanation
Folate is the exception to the rule stated because even though it is a water-soluble vitamin, it requires pre-absorption chemical digestion. Unlike other water-soluble vitamins, folate needs to be converted into its active form before it can be absorbed by the body. This conversion process occurs in the intestines with the help of enzymes. Once converted, folate can be absorbed through specific apical transporters. Therefore, folate does not follow the general rule for water-soluble vitamins and requires additional steps for absorption.Rate this question:
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- 19.
Tom Jones is a 52 yr old man with a long-standing history of alcohol abuse, who comes to see his Primary Care Physician because he has been losing his balance lately. He is accompanied by his wife, who adds that his memory also seems to be getting worse. Based on this patient's report, what is the most likely vitamin or mineral deficiency that would explain those symptoms.
- A.
Vitamin D
- B.
Thiamine
- C.
Calcium
- D.
Vitamin A
- E.
Iron
Correct Answer
B. ThiamineExplanation
Given the patient's history of alcohol abuse and symptoms of balance loss and memory decline, the most likely explanation for these symptoms is a thiamine deficiency. Alcohol abuse can lead to poor nutrition and impaired absorption of thiamine, which is essential for proper brain function. Thiamine deficiency can cause neurological symptoms such as balance problems and memory impairment. Therefore, a thiamine deficiency is the most likely explanation for this patient's symptoms.Rate this question:
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