Nokea
Which of the following is not an example of a homeostatic mechanism in the human body?
- A. Shivering when the body temperature falls below normal.
- B. Increasing heart rate and force of contraction when blood pressure falls.
- C. Retaining fluid excessively.
- D. Secreting insulin after a meal to return blood sugar concentration toward normal.
Correct Answer: C
Rationale: The correct answer is C. Homeostatic mechanisms aim to maintain internal stability within the body. Choices A, B, and D all represent examples of homeostatic mechanisms. Shivering helps generate heat to raise body temperature back to normal levels. Increasing heart rate and force of contraction work to restore blood pressure. Insulin secretion after a meal helps regulate blood sugar levels. On the other hand, retaining fluid excessively can lead to fluid imbalance rather than maintaining internal stability, making it the incorrect choice.
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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.
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.
Temperature is a form of energy, whereas heat is a measurement of the intensity of the temperature.
- A. TRUE
- B. FALSE
- C. Not Sure
- D. None of the above
Correct Answer: A
Rationale: The statement is true. Temperature is a measure of the average kinetic energy of the particles in a substance, while heat is the transfer of energy from a hotter object to a colder one. Heat is not a measurement of the intensity of temperature, but rather the energy transfer due to a temperature difference. Therefore, the correct answer is True. Choice B (False) is incorrect as the statement is true based on the definitions of temperature and heat.
Is the elbow distal to the wrist?
- A. TRUE
- B. FALSE
- C. Not Sure
- D. None of the above
Correct Answer: B
Rationale: The correct answer is False. In anatomical terms, 'distal' means farther away from the center of the body or the point of attachment. The elbow is proximal to the wrist because it is closer to the center of the body. Therefore, the statement that the elbow is distal to the wrist is incorrect. Choice A is incorrect because the elbow is not distal to the wrist. Choice C is incorrect as the anatomical relationship between the elbow and wrist can be determined. Choice D is incorrect as there is a definitive answer to this anatomical question.
Blood cells are produced in the organs of the _______ system.
- A. endocrine
- B. skeletal
- C. superior to
- D. inferior to
Correct Answer: C
Rationale: Blood cells are produced in the organs of the hematopoietic system. The correct answer is 'superior to' as this refers to the location of the organs responsible for blood cell production, typically bone marrow found in bones such as the vertebrae, ribs, and skull. 'Endocrine' (Choice A) refers to a different system responsible for hormone production. 'Skeletal' (Choice B) relates to bones but not specifically to the production of blood cells. Choices C and D, 'superior to' and 'inferior to,' do not make sense in the context of blood cell production and are incorrect.