Each statement is true of calcium within saliva, except one. Which is the exception?

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.

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.

Correct Answer: D

Rationale: The correct answer is D, Osmosis. Osmosis is the process where water moves from an area of low solute concentration to an area of high solute concentration. This movement equalizes the solute concentration in intracellular and extracellular fluids. Choices A, B, and C are incorrect because they do not describe the movement of water based on solute concentration levels.

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.

Correct Answer: C

Rationale: The correct answer is C. The first statement is true as the nutrient facts panel was indeed established by the USDA and the FDA to improve health and well-being by enhancing nutritional knowledge. However, the second statement is false. Nutrient content claims actually refer to the amount of a nutrient in a food, not to the relationship between a food and disease risk. Therefore, the second statement is incorrect, making choice C the correct option. Choice A is incorrect because the second statement is false. Choice B is incorrect as the first statement is true. Choice D is incorrect because the second statement is false.

Correct Answer: B

Rationale: Both statements are false. While Healthy People (HP 2020) has contributed to a reduction in deaths from cardiovascular disease, stroke, and some cancers, it did not result in decreased dental caries in children aged 2 to 4 years and adults aged 53 to 44 years. Therefore, the correct answer is B. Choice A is incorrect because the second statement is false. Choice C is incorrect as the first statement is also false. Choice D is incorrect as the second statement is false.

Correct Answer: A

Rationale: Both the statement and the reason are correct and related. The Institute of Medicine (IOM) recommends 18 mg of iron per day for women 19 to 50 years old, 8 mg/day for women 51 years old and older, and men 19 years old and older. During menstruation, women lose blood containing iron, leading to a higher iron requirement in premenopausal women compared to men or postmenopausal women. This increased demand aims to replenish the iron lost during this physiological process. Therefore, the statement and reason are directly linked, explaining why the RDA for iron is higher in premenopausal women than in men or postmenopausal women. Choices B, C, and D are incorrect as they do not accurately assess the relationship between the statement and the reason provided in the question.

Correct Answer: D

Rationale: The correct answer is D, Vitamins. While proteins, carbohydrates, and fats provide energy, vitamins do not. Vitamins are essential micronutrients that help regulate various biochemical processes in the body, such as metabolism and immunity. Choice A, B, and C are incorrect because proteins, carbohydrates, and fats are macronutrients that the body uses as a source of energy.

Correct Answer: B

Rationale: The correct answer is B. Magnesium plays an important role in maintaining calcium homeostasis and preventing skeletal abnormalities. It is involved in more than 300 enzymatic reactions, including energy metabolism, insulin activity, and glucose use. Magnesium is vital to the structural integrity of heart muscle and other muscles and nerves. While magnesium does play a role in blood clotting, nerve impulses, muscle contraction, relaxation, ATP energy release, and metabolism of fats, carbohydrates, proteins, the primary physiologic role of magnesium in the body is related to calcium homeostasis and maintaining the structural integrity of the heart muscle. Choice A is incorrect because it includes functions of magnesium, but they are not its primary physiologic role. Choice C is incorrect as magnesium has several known metabolic functions. Choice D is incorrect because although magnesium is involved in ATP energy release and metabolism, its primary role is related to calcium homeostasis and structural integrity of muscle.