Each statement regarding the correlation between vitamin D and sun exposure is accurate, except one. Which is the exception?

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: A

Rationale: Both statements are true. When rickets occurs, the alveolar bone is affected similar to other bones in the body, with the trabeculae of the alveolar bone also weakening. In addition to damaged alveolar bone caused by vitamin D deficiency, dental changes include delayed dentition and small molars. The other choices are incorrect because both statements provided are accurate based on the effects of rickets on the alveolar bone.

Correct Answer: D

Rationale: The correct answer is D: Potassium. Chronic potassium deficiency can lead to hypertension, heart attack, stroke, kidney stones, and osteoporosis. Patients experiencing this deficiency may feel tired, weak, and irritable without knowing the cause. Choice A (Zinc) is incorrect as zinc deficiency presents with different symptoms. Choice B (Iron) deficiency is associated with anemia symptoms, not the conditions listed. Choice C (Sodium) deficiency typically manifests as muscle cramps, weakness, and confusion, not the conditions described in the question.

Correct Answer: D

Rationale: Total kilocalories have the greatest effect on body weight as they represent the overall energy intake from all macronutrients combined. While the consumption of specific macronutrients like carbohydrates, proteins, and fats can affect weight management, the total calories consumed play the most significant role in determining body weight. Therefore, choices A, B, and C are incorrect as they focus on individual macronutrients rather than the overall energy balance provided by total kilocalories.

Correct Answer: A

Rationale: Both statements are true. Approximately 75% of reputable producers of bottled water use groundwater as their water source, which is the same source as the public water supply. Plain tap water, coming from underground sources or reservoirs, is indeed a natural source of fluids. The first statement is supported by the fact that groundwater is a common source for bottled water due to its purity and taste. The second statement is true as tap water is sourced from natural reservoirs or underground aquifers in most cases, making it a natural fluid source for consumption. Other choices are incorrect because both statements are factually accurate based on common practices in the production and sourcing of bottled water and tap water.

Correct Answer: D

Rationale: The correct answer is D. Phosphorus plays a crucial role in ATP energy release, the metabolism of fats, carbohydrates, and proteins, and regulation of acid-base balance. Choices A, B, and C are incorrect. Phosphorus is not directly involved in blood clotting, transmission of nerve impulses, muscle contraction, or calcium homeostasis. It also has known metabolic functions and is not associated with caries prevention.

Correct Answer: C

Rationale: Fat-soluble vitamins are not stored in the pancreas; they are stored in the liver and fatty tissues. Choice A is correct as fat-soluble vitamins are fairly stable to heat. Choice B is also correct as fat-soluble vitamins contain carbon. Choice D is correct as fat-soluble vitamins are absorbed in the intestine along with fats and lipids in food.

Correct Answer: B

Rationale: Rickets is caused by vitamin D deficiency, not vitamin C deficiency. It usually occurs in children who are 1 to 3 years old. The name rickets came from the word 'wrikken,' meaning 'to bend or twist.' Common manifestations of rickets include tachetic deformities like bow legs or knock-knees, a narrow and distorted chest, and failure of the epiphyses of bones to develop normally, resulting in twisted and warped bones. While the diagnosis of rickets may be increasing in the United States, it is not caused by a lack of vitamin C.

Correct Answer: B

Rationale: A deficiency in iron can lead to various symptoms, such as microcytic anemia, fatigue, faulty digestion, blue sclerae, pale conjunctivae, and tachycardia. Iron-deficiency anemia may be caused by inadequate dietary intake; accelerated demand or losses; and inadequate absorption secondary to diarrhea, decreased acid secretions, or antacid therapy. Iron deficiency is frequently the result of postnatal feeding practices and has a serious impact on growth and mental and psychomotor development in infants and children. Choices A, C, and D are incorrect as zinc deficiency typically presents with symptoms like impaired wound healing, taste abnormalities, and hair loss; sodium deficiency can lead to symptoms such as muscle cramps, dizziness, and confusion; and potassium deficiency may cause muscle weakness, fatigue, and abnormal heart rhythms.