Correct Answer: C

Rationale: The correct answer is C: Water. Water is essential for the human body to survive as it plays a crucial role in various physiological processes like digestion, circulation, and temperature regulation. Nitrogen is abundant in the atmosphere and is not directly obtained from the environment for survival. Waste products are materials that need to be eliminated from the body, not obtained for sustenance. Carbon dioxide is a byproduct of cellular respiration and is expelled from the body through breathing, not obtained as a nutrient.

Correct Answer: B

Rationale: Homeostasis is the body's ability to maintain stable internal conditions despite external changes. To achieve this balance, concentrations of essential substances must remain within specific ranges. Choice A is incorrect because decreasing concentrations would not maintain stability. Choice C is incorrect as increasing concentrations when the body is stressed would disrupt homeostasis. Choice D is incorrect as fluctuating greatly between high and low values would also not support the body's stability. Therefore, the correct answer is B, as it aligns with the concept of homeostasis by emphasizing the need for stability within certain limits.

Correct Answer: D

Rationale: The term 'physiology' originates from the Greek words 'physis' (meaning nature) and 'logos' (meaning study or relationship). Therefore, the correct answer is 'the Greek for 'relationship to nature.' Choice A is incorrect as it refers to the Latin meaning of 'physiology,' not the Greek origin. Choice B is incorrect as it is specific to the structure of internal organs, not the overall study of nature. Choice C is incorrect as it refers to a different term related to dissection or anatomy, not physiology.

Correct Answer: A

Rationale: An anatomist focuses on observing the structure and morphology of body parts, such as organs, tissues, and cells, to understand their organization. On the other hand, a physiologist is more concerned with studying the functions and processes of these body parts, including how they work individually and together to maintain homeostasis. Therefore, the correct answer is 'observing body parts; studying functions of body parts.' Choices B, C, and D are incorrect as they do not accurately reflect the primary activities of anatomists and physiologists.

Correct Answer: D

Rationale: The correct answer is "epigastric." The epigastric region is located in the upper midportion of the abdomen, between the hypochondriac regions on either side. Choice A, "hypochondriac," refers to the upper lateral regions of the abdomen beneath the ribs. Choice B, "iliac," pertains to the lower lateral regions of the abdomen. Choice C, "hypogastric," is the lower central region of the abdomen.