Which of the following statements is correct?

Correct Answer: A

Rationale: The correct statement is that people with less body fat have more body water. This is because fat tissue contains less water compared to lean tissue, so individuals with less body fat generally have a higher percentage of body water. Choice B is incorrect as infants actually have more water per pound than adults due to their higher body water content. Choice C is incorrect as males typically have more body water per pound than females. Choice D is incorrect as infants have a higher water content per pound compared to adults.

Correct Answer: D

Rationale: The correct answer is D. The sources of water intake include drinking fluids, consuming water from the food we eat, and water from metabolic processes. Water intake is not solely from the liquids we drink but also from the water content present in the food we consume and the water produced during metabolic processes such as cellular respiration. Therefore, option D is the correct answer as it covers all the sources of water intake. Options A, B, and C alone do not encompass all the sources of water intake, making them incorrect choices.

Correct Answer: A

Rationale: The correct answer is the kidneys. The kidneys are primarily responsible for regulating fluid balance by filtering blood and adjusting the volume and concentration of urine. The lungs primarily regulate gas exchange, not fluid balance. The skin plays a role in temperature regulation and protection but is not the primary organ for fluid output. The intestines are mainly involved in the absorption of nutrients and water, rather than fluid output.

Correct Answer: B

Rationale: The correct answer is 'aldosterone.' Aldosterone is the hormone that reduces the amount of water in the body by increasing the reabsorption of sodium and water from the kidney tubules. ANH (atrial natriuretic hormone) actually works to increase the excretion of sodium and water by the kidneys, leading to a reduction in blood volume and pressure. ADH (antidiuretic hormone) works to increase water reabsorption by the kidneys, thereby increasing blood volume. Therefore, choices A (ADH) and D (ADH and aldosterone) are incorrect in the context of reducing the amount of water in the body.

Correct Answer: D

Rationale: The correct answer is D, ADH and aldosterone. Both antidiuretic hormone (ADH) and aldosterone increase water retention by the kidneys, thereby increasing blood volume. ADH acts on the kidneys to increase water reabsorption, while aldosterone acts on the kidneys to promote sodium reabsorption, leading to water retention. Choice A, ADH, is partially correct as it alone increases water retention. Choice B, aldosterone, is also partially correct as it alone increases water retention. Choice C, ANH (atrial natriuretic hormone), actually decreases water retention by promoting sodium excretion and inhibiting aldosterone release.