Nursing Elites

1. Maintaining a stable internal environment typically requires

• A. positive feedback mechanisms.
• B. an unstable outside environment.
• C. decreased atmospheric pressure.
• D. negative feedback mechanisms.

Correct answer: D

Rationale: The correct answer is 'negative feedback mechanisms.' In biological systems, negative feedback mechanisms help maintain homeostasis by counteracting any deviations from the set point. They work to stabilize internal conditions and keep them within a narrow range. On the other hand, positive feedback mechanisms amplify changes and are not involved in maintaining stability. Choice B, 'an unstable outside environment,' is incorrect as internal stability is independent of external conditions like weather. Choice C, 'decreased atmospheric pressure,' is also incorrect as it does not directly relate to internal homeostasis.

2. Which of the following illustrates a positive feedback mechanism?

• A. Maintaining blood pressure
• B. Uterine contractions during childbirth
• C. Body temperature control
• D. Control of blood sugar

Correct answer: B

Rationale: The correct answer is uterine contractions during childbirth. This is an example of a positive feedback mechanism where the initial stimulus (contractions) leads to an increase in intensity and frequency, ultimately resulting in childbirth. In contrast, choices A, C, and D (maintaining blood pressure, body temperature control, and control of blood sugar) are examples of negative feedback mechanisms. These mechanisms work to maintain stability by counteracting any deviations from the set point, rather than amplifying the response like in a positive feedback mechanism.

3. Which of the following must the human body obtain from the environment in order to survive?

• A. Nitrogen
• B. Waste products
• C. Water
• D. Carbon dioxide

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.

4. What is assimilation?

• A. changing absorbed substances into different chemical forms
• B. breaking down foods into nutrients that the body can absorb
• C. eliminating waste from the body
• D. an increase in body size without a change in overall shape

Correct answer: A

Rationale: Assimilation is the process of changing absorbed substances into different chemical forms. It occurs after nutrients from food are absorbed into the bloodstream and used by the body. Choice B, breaking down foods into nutrients that the body can absorb, refers to the process of digestion rather than assimilation. Choice C, eliminating waste from the body, describes the process of excretion. Choice D, an increase in body size without a change in overall shape, does not accurately define assimilation.

5. Homeostasis exists if concentrations of water, nutrients, and oxygen in the body and heat and pressure __________.

• A. decrease steadily
• B. remain within certain limited ranges
• C. increase when the body is stressed
• D. fluctuate greatly between very high and low values

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.

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