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What do positive feedback mechanisms do?
- A. Cause long-term changes.
- B. Move conditions away from the normal state.
- C. Bring conditions back to the normal state.
- D. Usually produce stable conditions.
Correct Answer: B
Rationale: Positive feedback mechanisms amplify or increase changes in a system, moving conditions away from the normal state. This makes choice B the correct answer. Choice A is incorrect as positive feedback does not cause long-term changes but rather accelerates deviations from the norm. Choice C is incorrect because positive feedback does not bring conditions back to normal; instead, it amplifies deviations. Choice D is incorrect as positive feedback does not usually lead to stable conditions but rather to further deviations from the normal state.
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An investigator who conducts an experiment to determine how temperature changes affect the rate at which the heart beats is most likely a(n)
- A. anatomist.
- B. physiologist.
- C. chemist.
- D. biochemist.
Correct Answer: B
Rationale: The correct answer is 'physiologist.' A physiologist studies how the body functions under normal and abnormal conditions, including how temperature changes can affect physiological processes like heart rate. An anatomist focuses on the structure of organisms rather than their functions, making choice A incorrect. Choices C and D are also incorrect as they are more related to the study of chemicals and biochemistry, which are not directly relevant to investigating the effects of temperature on heart rate.
A parietal layer of a serous membrane lines cavities, whereas a visceral layer of a serous membrane covers organs.
- A. covers organs; lines cavities
- B. lines cavities; covers organs
- C. secretes serous fluid; secretes mucus
- D. secretes mucus; secretes a serous fluid
Correct Answer: B
Rationale: In serous membranes, the parietal layer lines the cavities, providing support and protection, while the visceral layer covers the organs, reducing friction and allowing them to move freely. Therefore, the correct answer is 'lines cavities; covers organs.' Choices C and D are incorrect because serous membranes do not secrete mucus; instead, they secrete a watery serous fluid. Choice A is incorrect as it reverses the functions of the parietal and visceral layers in relation to organs and cavities.
The recent discovery of taste receptors that detect sweetness in the small intestine illustrates that
- A. chemical responses occur in various parts of the body.
- B. new discoveries about anatomy and physiology are still being made.
- C. everything about anatomy and physiology has been discovered.
- D. the molecular and cellular level is crucial in anatomy and physiology.
Correct Answer: B
Rationale: The recent discovery of taste receptors in the small intestine illustrates that new discoveries about anatomy and physiology are still being made. This finding demonstrates that our understanding of the human body is continuously evolving. Choice A is incorrect because the discovery does not imply that chemical responses occur in only one part of the body but rather showcases a specific new discovery. Choice C is incorrect as it is highly improbable that everything about anatomy and physiology has been discovered given the complexity of the human body. Choice D is incorrect as while the molecular and cellular level is important in anatomy and physiology, the primary focus of this discovery is on the new findings about the taste receptors in the small intestine.
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.
Simple squamous epithelium is an example of a(n)
- A. organ system.
- B. organ.
- C. tissue.
- D. molecule.
Correct Answer: C
Rationale: Simple squamous epithelium is a type of tissue, not an organ system, organ, or molecule. Tissues are groups of cells that work together to perform a specific function. In this case, simple squamous epithelium is a thin, single layer of flattened cells that line surfaces involved in passive diffusion, such as the alveoli in the lungs or blood vessels. Therefore, the correct answer is 'tissue.' Choices A, B, and D are incorrect as they do not accurately categorize simple squamous epithelium as a tissue.