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What is the best summary of the passage?
- A. Electric currents within the body are due to electrostatic charges set off by the heart. Medical staff are trained to recognize any abnormalities within the heart.
- B. Every individual has unique electric currents on the surface of the body. The ECG measures and records these electric currents.
- C. The ECG systematically and rather quickly measures the stages at which the 'wave of excitation' occurs within the heart and records them. This wave has three distinct steps that spread from the SA node to the AV node.
- D. The ECG measures the electric currents within the body. These currents are detected on the surface of the body when the body is connected to an amplifier.
Correct Answer: C
Rationale: The correct summary of the passage is option C. The passage explains how the ECG systematically measures and records the 'wave of excitation' that occurs within the heart in three distinct steps, spreading from the SA node to the AV node. This summary effectively captures the main focus of the passage. Option A is incorrect because it only mentions the detection of electric currents in the body and recognizing abnormalities by medical staff, missing the key information about the 'wave of excitation' and its stages. Option B is incorrect as it focuses solely on the measurement and recording of unique electric currents on the body's surface, neglecting the specific process described in the passage. Option D is also incorrect as it provides a general description of how the ECG measures electric currents without emphasizing the specific stages of the 'wave of excitation' as detailed in the passage.
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What is a major difference in the way baroreceptors and chemoreceptors work from the way the kidneys work?
- A. Baroreceptors and chemoreceptors send impulses from the arteries, while the kidneys control blood volume.
- B. Baroreceptors and chemoreceptors both work to help maintain blood volume, whereas the kidneys take care of salts, water, and waste removal.
- C. Baroreceptors and chemoreceptors must work together to control blood pressure, whereas the kidneys work with the adrenal cortex.
- D. Baroreceptors and chemoreceptors are both located near the adrenal cortex, whereas the kidneys are located near the heart.
Correct Answer: A
Rationale: The correct answer is A. Baroreceptors and chemoreceptors send impulses from the arteries, while the kidneys control blood volume. Baroreceptors and chemoreceptors are responsible for monitoring blood pressure by sensing changes in pressure, oxygen levels, carbon dioxide levels, and pH within the arteries. They send out impulses to raise or lower blood pressure accordingly. On the other hand, the kidneys play a crucial role in regulating blood volume by absorbing salts and water and removing waste products. This key difference highlights that while baroreceptors and chemoreceptors are involved in monitoring and regulating blood pressure, the kidneys primarily focus on controlling blood volume. Choice B is incorrect because it inaccurately states that baroreceptors and chemoreceptors help maintain blood volume, which is not their primary function. Choice C is incorrect as it provides an inaccurate comparison between the roles of baroreceptors, chemoreceptors, and the kidneys. Choice D is incorrect as it wrongly associates the location of baroreceptors and chemoreceptors with the adrenal cortex, which is not accurate.
What is the subject of the passage?
- A. foodborne illnesses
- B. the dangers of uncooked food
- C. bacteria
- D. proper food preparation
Correct Answer: A
Rationale: The correct answer is A: 'foodborne illnesses.' The passage discusses how foodborne illnesses are contracted by consuming contaminated food or beverages, the symptoms they can cause, common sources of contamination like bacteria, viruses, and chemicals, and preventive measures. While the passage mentions dangers associated with uncooked food, bacteria, and proper food preparation, the primary focus is on foodborne illnesses caused by various contaminants. Choice B, 'the dangers of uncooked food,' is incorrect as it is a narrower focus compared to the broader topic of foodborne illnesses. Choice C, 'bacteria,' is incorrect as it is one of the contaminants discussed in relation to foodborne illnesses but not the central subject of the passage. Choice D, 'proper food preparation,' is incorrect as it is mentioned in the passage but not as the main subject; rather, it is discussed as a preventive measure to avoid foodborne illnesses.
What is the meaning of the word 'emitting' as it is used in the second paragraph?
- A. Repelling
- B. Releasing
- C. Closing
- D. Charging
Correct Answer: B
Rationale: In the context provided, 'emitting' means releasing, specifically referring to the electric currents being released in the body. The passage describes how electric currents are constantly being emitted in the body and can be detected on the body's surface, ultimately recorded by an electrocardiograph. This process is about the release of electric impulses, making 'releasing' the correct interpretation. Choice A, 'Repelling,' implies pushing away, which is not the intended meaning in this context. Choice C, 'Closing,' and Choice D, 'Charging,' do not align with the context of electric currents being emitted.
What is the meaning of the word 'phenomenon' in the second paragraph?
- A. Something that is lifeless to the senses
- B. Something that is nonchalant
- C. Something that is significant but unusual
- D. Something that is chemical in origin
Correct Answer: C
Rationale: In the context of the second paragraph, 'phenomenon' refers to something significant and unusual, specifically describing the scientific phenomenon known as the Doppler Effect. This effect explains the change in frequency of sound waves when a source of sound and the observer are in relative motion. Choices A, B, and D are incorrect because they do not accurately reflect the meaning of 'phenomenon' in this context. 'Lifeless to the senses,' 'nonchalant,' and 'chemical in origin' do not align with the description of the Doppler Effect, which is a notable and uncommon scientific occurrence.
Which statement is not listed as a detail within the passage?
- A. Changes in the ECG are typically used for the diagnosis of abnormal cardiac rhythm.
- B. The signal has a characteristic record called the electrocardiogram.
- C. The 'wave of excitation' starts at the SA node.
- D. The 'wave of excitation' spreads through the heart wall and is accompanied by electric changes.
Correct Answer: A
Rationale: The corrected statement should be: Changes in the ECG are not typically used for the diagnosis of abnormal cardiac rhythm. The passage mentions that the heart sends out electric currents in waves, and the 'wave of excitation' spreads through the heart wall accompanied by electric changes. It details the process of how the heart's electric impulses are recorded and how abnormalities can be detected. However, it does not state that ECG changes are specifically used for diagnosing abnormal cardiac rhythms. Choice A is the correct answer because it misrepresents the information provided in the passage. Choices B, C, and D are all supported by the passage and align with the details mentioned regarding the electrocardiogram and the wave of excitation in the heart.