Correct Answer: A

Rationale: The correct answer is A: 80%. Newborns can have a body water content as high as 80% due to their higher total body water compared to adults. Choice B (70%) is incorrect because newborns typically have a higher body water percentage. Choice C (60%) is also incorrect as it underestimates the body water content in newborns. Choice D (90%) is incorrect as it overestimates the body water percentage in newborns.

Correct Answer: D

Rationale: Intracellular fluid contains phosphate ions and protein molecules as essential anions. Phosphate ions play a crucial role in various cellular processes, including energy transfer. Proteins, being large molecules with negative charges, also contribute significantly to the negative ion concentration within cells. Chlorine is primarily an extracellular anion and is not as prominent as phosphate ions and proteins within intracellular fluid, making it a less important negative ion in this context. Therefore, the correct answer is D because both phosphate ions and protein molecules are crucial negative ions in intracellular fluid.

Correct Answer: C

Rationale: Inelastic skin is a normal change of aging. However, this does not mean that skin turgor cannot be assessed in older patients. Dehydration, not overhydration, causes inelastic skin with tenting. Overhydration, not dehydration, causes the skin to appear edematous and spongy. Choice A is incorrect because overhydration is not common among healthy older adults. Choice B is incorrect because dehydration leads to inelastic skin, not sponginess. Choice D is incorrect as skin turgor assessment can be done in patients of any age, including those over 70.

Correct Answer: C

Rationale: Iron (Fe) is a critical mineral in hemoglobin production. Hemoglobin is a protein found in red blood cells that is essential for transporting oxygen throughout the body. Sodium (Choice A), Iodine (Choice B), and Chloride (Choice D) are not directly involved in hemoglobin production. Sodium is an electrolyte that helps maintain fluid balance, Iodine is essential for thyroid hormone production, and Chloride is an electrolyte that helps regulate fluid balance and acidity in the body.

Correct Answer: D

Rationale: Dehydration can result from significant fluid loss due to vomiting, diarrhea, or inadequate fluid intake. Prolonged vomiting and diarrhea lead to excessive fluid loss from the body, contributing to dehydration. Similarly, not consuming enough fluids can also result in dehydration. Choice A and B are too specific as they only mention one cause each, while choice C is also correct but does not encompass all the potential causes of dehydration as mentioned in choice D.