Which sound waves have a lower pitch?

Correct Answer: B

Rationale: Sound waves that are farther apart have a lower pitch. The Doppler Effect explains that as objects emitting sound move away, the sound waves become more spaced out, resulting in a lower frequency and a lower pitch. Choice A is incorrect because waves that are closer together have a higher frequency and a higher pitch. Choices C and D are not directly related to determining the pitch of sound waves.

Correct Answer: A

Rationale: In the context provided, 'composed' means to consist of. The paragraph explains that a drop of water is composed of an oxygen atom and two hydrogen atoms. Therefore, the correct answer is A. Choice B, 'To be uniquely discovered,' is incorrect as it does not relate to the composition of a drop of water. Choice C, 'To be set apart,' and Choice D, 'To be surprised,' are also incorrect as they do not convey the meaning of 'composed' as it is used in this paragraph.

Correct Answer: A

Rationale: The correct answer is 'A: requiring expert knowledge.' In the context provided, 'technical' refers to articles that demand expert knowledge to understand. The passage mentions that articles published in medical journals can be technical, meaning they are complex and require specialized expertise to comprehend. Choice B, 'incomplete,' is incorrect as 'technical' does not imply incompleteness. Choices C and D, 'foreign' and 'plagiarized,' are also incorrect as they do not align with the context of the passage.

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.

Correct Answer: C

Rationale: 'Phased in' means implemented in stages, referring to the gradual implementation of good manufacturing practices. In the provided extract, it mentions that requirements for good manufacturing practices (GMPs) were phased in for small manufacturers through 2010, indicating a gradual implementation process. The other choices, 'stunned into silence,' 'confused,' and 'legalized,' do not accurately reflect the meaning of 'phased in' in the context of the paragraph.

Correct Answer: C

Rationale: The primary purpose of the essay is to inform the reader about how the cardiovascular system regulates blood pressure. The essay provides detailed explanations about the components of the cardiovascular system that regulate blood pressure, such as baroreceptors, chemoreceptors, and the kidneys. Choices A and B are incorrect because the essay does not focus on discussing the dangers of high blood pressure or its correlation with a higher risk of heart attack. Choice D is incorrect as the essay does not aim to persuade the reader to control their blood pressure but rather to educate them on the regulatory mechanisms of the cardiovascular system.

Correct Answer: D

Rationale: The correct steps of the 'wave of excitation' are the excitation of the atrium, excitement of the ventricle, and relaxation of the ventricle. In the described process, the 'wave of excitation' starts with the discharge from the SA node, leading to the excitation of the atrium. Next, the peak ECG corresponds to the excitement of the ventricle, not its relaxation. Finally, the wave concludes with the relaxation of the ventricle, not its contraction. Therefore, choices A, B, and C are incorrect as they do not accurately describe the sequential steps of the 'wave of excitation' as presented in the extract.

Correct Answer: A

Rationale: In the context of the immune system, 'enlist' means to call into service. Immune cells recruit other cells to fight infection by producing chemicals that regulate their growth, behavior, and direct new recruits to trouble spots. This process is essential for the immune system's defense mechanism. The other choices are incorrect: 'write down' and 'put across' do not capture the action of mobilizing immune cells, and 'send away' is opposite in meaning to what is happening in the immune response.

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.