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Questions and Answers
What type of vitamins can lead to toxicity when consumed in excess?
Which vitamin is primarily formed in the skin upon exposure to sunlight?
What is the main function of B vitamins in the body?
Which vitamin deficiency is associated with the disease beriberi?
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What type of compounds are lipid-soluble vitamins described as?
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What symptom is NOT characteristic of riboflavin (Vitamin B2) deficiency?
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Which of the following is a source of preformed Vitamin A?
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Which vitamin can be formed from the amino acid tryptophan?
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What condition is primarily associated with vitamin D toxicity in adults?
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What is one of the three ways calcitriol increases calcium levels in the body?
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Which vitamin D precursor is converted to calcitriol through hydroxylation in the liver?
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What happens to infants who consume vitamin D at very low doses?
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What role does parathormone (PTH) play in calcium regulation?
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How does excessive exposure to sunlight affect the formation of vitamin D precursors?
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What is one consequence of elevated serum calcium related to vitamin D toxicity?
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What is the function of calcitonin in calcium regulation?
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What is the role of retinoic acid in the body?
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What occurs as a result of vitamin A deficiency?
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Which process initiates a nerve impulse in photoreceptors?
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What are some symptoms of vitamin A toxicity?
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What type of receptors does retinoic acid bind to?
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What is the significance of 11-cis-retinaldehyde in phototransduction?
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In what way does vitamin D differ from retinoic acid?
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What is the consequence of unbound vitamin A in the body?
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Which compound is NOT a biologically active form of vitamin K?
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What is the role of thiamine diphosphate in metabolism?
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Which of the following factors is NOT part of the blood clotting system regulated by vitamin K?
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Which vitamin is responsible for the synthesis of certain proteins in the blood clotting system?
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What is a key feature of gamma-carboxyglutamate residues?
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Which metabolic pathways are associated with thiamine in carbohydrate metabolism?
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Which vitamin is synthesized by intestinal bacteria?
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What does thiamine specifically assist in regarding branched-chain keto acids?
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What condition is primarily associated with vitamin D deficiency in young individuals?
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What is the earliest sign of vitamin A deficiency?
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Which vitamin is linked to the hemorrhagic disease of the newborn?
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What is a potential consequence of vitamin A deficiency on vitamin D?
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What function do Retinoid X Receptors (RXR) primarily serve?
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How are the two isoenzymes of carotene dioxygenase differentiated?
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What vitamin deficiency can lead to hemolytic anemia in newborns?
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What impairment occurs first due to vitamin A deficiency?
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Study Notes
Micronutrients: Vitamins Overview
- Vitamins are essential organic compounds required in small amounts for metabolic integrity.
- Water-soluble vitamins include B vitamins, C, Niacin, Folic Acid, Biotin, and Pantothenic Acid; they act primarily as enzyme cofactors.
- Lipid-soluble vitamins comprise A, D, E, and K; toxicity can arise from excess intake.
Vitamin A (Retinol)
- Retinol is important for vision, immune function, and cellular growth.
- Deficiency leads to night blindness, impaired adaptation to darkness, and increased susceptibility to infectious diseases.
- Sources include food of animal origin; carotenoids in plant sources can also be converted to retinoids via enzymatic processes.
Vitamin D
- Synthesized in the skin from 7-dehydrocholesterol upon sunlight exposure.
- Regulates calcium and phosphorus levels through calcitriol, increasing intestinal absorption and reducing excretion.
- Deficiency results in Rickets in children and Osteomalacia in adults, characterized by softening of bones.
Vitamin E
- Acts as an antioxidant and protects cell membranes.
- Deficiency can cause hemolytic anemia in newborns due to oxidative stress.
Vitamin K
- Exists as phylloquinone (plant source), menaquinone (bacteria), and synthetic forms.
- Essential for synthesis of clotting factors in the blood including Factors II, VII, IX, and X.
- Gamma-carboxyglutamate residues in clotting proteins allow for calcium ion binding, crucial for blood coagulation.
Thiamine (Vitamin B1)
- Coenzyme for three multienzyme complexes involved in metabolic pathways such as carbohydrate metabolism.
- Deficiency can lead to conditions like Beriberi, marked by neurological and cardiovascular issues.
Key Points on Toxicity
- Excess vitamin A can cause neurological symptoms and liver toxicity.
- High vitamin D intake may cause hypercalcemia, high blood pressure, and calcification of soft tissues, though sunlight exposure mitigates toxicity risks.
- Balanced intake of vitamins is crucial for avoiding deficiency or toxicity-related disorders.
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Description
Explore the crucial role of vitamins as micronutrients in human metabolism. This quiz covers the types of vitamins, their sources, and the effects of vitamin toxicity. Understand the differences between lipid-soluble and water-soluble vitamins to enhance your biochemistry knowledge.