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Each statement is true of calcium within saliva, except one. Which is the exception?
- A. Saliva is supersaturated with calcium.
- B. Saliva is a source of calcium to mineralize an immature or demineralized enamel surface.
- C. Calcium and phosphate in saliva provide a buffering action.
- D. Calcium within saliva increases dental caries.
Correct Answer: D
Rationale: The correct answer is D. Calcium within saliva does not increase dental caries; in fact, the buffering action provided by calcium and phosphate in saliva inhibits caries formation by preventing the dissolution of enamel by plaque biofilm. Choice A is correct as saliva is indeed supersaturated with calcium. Choice B is correct as saliva serves as a source of calcium to mineralize an immature or demineralized enamel surface. Choice C is correct as calcium and phosphate in saliva do provide a buffering action to protect teeth from acids.
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Each of the following is a form of vitamin K, except one. Which is the exception?
- A. Phylloquinone
- B. Tocopherol
- C. Menaquinone
- D. Menadione
Correct Answer: B
Rationale: Tocopherol, Choice B, is not a form of vitamin K; it is another name for vitamin E. Phylloquinone (Choice A), menaquinone (Choice C), and menadione (Choice D) are all forms of vitamin K. Phylloquinone is vitamin K1 found in green plants, menaquinone is vitamin K2 produced in the large intestine and found in animal tissues, and menadione is a synthetic form of vitamin K. Therefore, Choice B is the correct answer because it does not belong to the vitamin K group, unlike the other options.
Each statement is true of vitamin K, except one. Which is the exception?
- A. Vitamin K is produced in the gut.
- B. Vitamin K functions as a catalyst for the synthesis of blood-clotting factors.
- C. Vitamin K maintains prothrombin levels.
- D. Vitamin K absorption increases with high levels of vitamin E supplementation.
Correct Answer: D
Rationale: The correct answer is D. Vitamin K absorption decreases with high levels of vitamin E supplementation because in larger amounts, vitamin E acts as an anticoagulant. Vitamin K is not produced in the gut but can be obtained from food sources or supplements. Vitamin K is essential for the synthesis of blood-clotting factors and is crucial in maintaining prothrombin levels, which is vital for proper blood clotting. The incorrect choice, D, is misleading as high levels of vitamin E supplementation hinder vitamin K absorption due to its anticoagulant properties. Dental hygienists should be aware of the importance of vitamin K in blood clotting, especially when treating patients who are on anticoagulant medications for conditions like stroke prevention.
Each statement regarding the correlation between vitamin D and sun exposure is accurate, except one. Which is the exception?
- A. The body can produce sufficient amounts of vitamin D from sunlight.
- B. UV radiation can convert a precursor of vitamin D to vitamin D3 by penetrating uncovered skin.
- C. Sunscreen blocks the formation of vitamin D3.
- D. By the age of 70 years, the skin generally produces vitamin D at only half the level it did at the age of 20 years.
Correct Answer: C
Rationale: While UV radiation can penetrate uncovered skin and convert a precursor of vitamin D to vitamin D3, sunscreen does block the formation of vitamin D3. Sunscreen is recommended by dermatologists to prevent sunburn and reduce the risk of skin cancer. The other choices are correct: the body can produce sufficient vitamin D from sunlight, UV radiation can convert a precursor of vitamin D to vitamin D3, and skin generally produces less vitamin D as a person ages.
Which set of guidelines is intended to assess nutrient adequacy or plan intakes of population groups, not individuals?
- A. Old Recommended Dietary Allowances (RDA)
- B. Estimated Average Requirement (EAR)
- C. New Recommended Dietary Allowances (RDA)
- D. Tolerable Upper Intake Level (UL)
Correct Answer: B
Rationale: The Estimated Average Requirement (EAR) is specifically designed to assess nutrient adequacy or plan intakes for population groups, not for individuals. The Old and New Recommended Dietary Allowances (RDA) are meant for individuals, not groups, as they provide guidelines for specific nutrient intake levels for healthy individuals. The Tolerable Upper Intake Level (UL) is used to set the highest level of nutrient intake that is likely to pose no risk of adverse health effects for most individuals in a group, which is different from assessing nutrient adequacy for groups.
The oral cavity is the site of a wide variety of systemic disease manifestations due to:
- A. Rapid cellular turnover
- B. Constant attack by microorganisms
- C. Trauma-intense environment
- D. All of the above
Correct Answer: D
Rationale: The oral cavity is indeed the site of various systemic disease manifestations due to multiple factors. Firstly, the rapid cellular turnover in the oral mucosa makes it susceptible to diseases. Secondly, the constant presence of microorganisms in the oral cavity contributes to the development of systemic diseases. Finally, the oral cavity being a trauma-intense environment further increases the risk of systemic manifestations. Therefore, all the provided options - rapid cellular turnover, constant attack by microorganisms, and a trauma-intense environment - play a role in making the oral cavity a site for various systemic diseases. Hence, the correct answer is 'All of the above.' Choices A, B, and C are incorrect individually as they each represent only one aspect of why the oral cavity is prone to systemic disease manifestations, whereas the correct answer encompasses all these factors.