Actual HESI A2 Test Questions Set 1

Reading Comprehension

The immune system is a network of cells, tissues, and organs that defends the body against attacks by foreign invaders. These invaders are primarily microbes—tiny organisms such as bacteria, parasites, and fungi—that can cause infections. Viruses also cause infections, but are too primitive to be classified as living organisms. The human body provides an ideal environment for many microbes. It is the immune system’s job to keep the microbes out or destroy them. The immune system is amazingly complex. It can recognize and remember millions of different enemies, and it can secrete fluids and cells to wipe out nearly all of them. The secret to its success is an elaborate and dynamic communications network. Millions of cells, organized into sets and subsets, gather and transfer information in response to an infection. Once immune cells receive the alarm, they produce powerful chemicals that help to regulate their own growth and behavior, enlist other immune cells, and direct the new recruits to trouble spots. Although scientists have learned much about the immune system, they continue to puzzle over how the body destroys invading microbes, infected cells, and tumors without harming healthy tissues. New technologies for identifying individual immune cells are now allowing scientists to determine quickly which targets are triggering an immune response. Improvements in microscopy are permitting the first-ever observations of living B cells, T cells, and other cells as they interact within lymph nodes and other body tissues. In addition, scientists are rapidly unraveling the genetic blueprints that direct the human immune response, as well as those that dictate the biology of bacteria, viruses, and parasites. The combination of new technology with expanded genetic information will no doubt reveal even more about how the body protects itself from disease.

Question 1.

What is the meaning of the word enlist as it is used in the second paragraph?

  • A: call into service
  • B: write down
  • C: send away
  • D: put across
  • Correct Answer: A

  • Rationale: The correct answer is A: 'call into service.' In the context of the paragraph, the word 'enlist' is used to describe the action of recruiting or bringing in other immune cells to trouble spots. This aligns with the meaning of 'call into service,' as it reflects the process of mobilizing additional immune cells to respond to an infection. The other choices, 'write down,' 'send away,' and 'put across,' do not accurately capture the intended meaning of 'enlist' in this context.
Have you ever wondered why the whistle of a traveling, distant locomotive predicts its approach several yards before anyone actually sees it? Or why an oncoming ambulance’s screaming siren is heard momentarily several feet before the ambulance comes into full view, before it passes you, and why its siren is still heard faintly well after the ambulance is out of sight? What you are witnessing is a scientific phenomenon known as the Doppler Effect. What takes place is truly remarkable. In both of these instances, when the train or ambulance moves toward the sound waves in front of it, the sound waves are pulled closer together and have a higher frequency. In either instance, the listener positioned in front of the moving object hears a higher pitch. The ambulance and locomotive are progressively moving away from the sound waves behind them, causing the waves to be farther apart and to have a lower frequency. These fast-approaching modes of transportation distance themselves past the listener, who hears a lower pitch.

Question 2:

Which statement is not listed as a detail in the passage?

  • A: The oncoming sound waves have a higher pitch because of high frequency and closeness of waves.
  • B: The oncoming sound waves have a higher pitch because of low frequency and closeness of waves.
  • C: The whistling sound of the locomotive as it approaches and passes can be explained by the Doppler effect.
  • D: The high-pitched sound of the ambulance as it approaches and passes can be explained by the Doppler effect.
  • Correct Answer: B

  • Rationale:
Have you ever wondered why the whistle of a traveling, distant locomotive predicts its approach several yards before anyone actually sees it? Or why an oncoming ambulance’s screaming siren is heard momentarily several feet before the ambulance comes into full view, before it passes you, and why its siren is still heard faintly well after the ambulance is out of sight? What you are witnessing is a scientific phenomenon known as the Doppler Effect. What takes place is truly remarkable. In both of these instances, when the train or ambulance moves toward the sound waves in front of it, the sound waves are pulled closer together and have a higher frequency. In either instance, the listener positioned in front of the moving object hears a higher pitch. The ambulance and locomotive are progressively moving away from the sound waves behind them, causing the waves to be farther apart and to have a lower frequency. These fast-approaching modes of transportation distance themselves past the listener, who hears a lower pitch.

Question 3:

What is the main idea of the passage?

  • A: Trains and ambulances produce specific sounds
  • B: Low-frequency waves produce high-pitched sounds.
  • C: High-frequency waves produce low-pitched sounds.
  • D: The Doppler Effect explains why sound is heard more strongly initially and then faintly after a moving object has passed.
  • Correct Answer: D

  • Rationale: The main idea of the passage is to explain the phenomenon known as the Doppler Effect, which describes how the frequency of sound waves changes as a source of sound moves relative to an observer. The passage illustrates this with examples of a traveling train and ambulance. As the objects approach the listener, the sound waves are compressed, resulting in a higher frequency and a higher pitch heard by the observer. Conversely, as the objects move away, the sound waves are stretched, leading to a lower frequency and a lower pitch. Therefore, the correct answer is D, as it summarizes the key concept of the Doppler Effect and its impact on sound perception.
Doppler Effect Have you ever wondered why the whistle of a traveling, distant locomotive predicts its approach several yards before anyone actually sees it? Or why an oncoming ambulance’s screaming siren is heard momentarily several feet before the ambulance comes into full view, before it passes you, and why its siren is still heard faintly well after the ambulance is out of sight? What you are witnessing is a scientific phenomenon known as the Doppler Effect. What takes place is truly remarkable. In both of these instances, when the train or ambulance moves toward the sound waves in front of it, the sound waves are pulled closer together and have a higher frequency. In either instance, the listener positioned in front of the moving object hears a higher pitch. The ambulance and locomotive are progressively moving away from the sound waves behind them, causing the waves to be farther apart and to have a lower frequency. These fast-approaching modes of transportation distance themselves past the listener, who hears a lower pitch.

Question 4:

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: The correct answer is C: 'Something that is significant but unusual.' In the context of the passage, the word 'phenomenon' refers to the scientific concept of the Doppler Effect, which is described as remarkable and not commonly observed in everyday situations. It is used to explain the unique behavior of sound waves when emitted by moving objects. Therefore, 'phenomenon' in this context signifies something that is notable, important, and out of the ordinary, making choice C the most appropriate answer.
Doppler Effect Have you ever wondered why the whistle of a traveling, distant locomotive predicts its approach several yards before anyone actually sees it? Or why an oncoming ambulance’s screaming siren is heard momentarily several feet before the ambulance comes into full view, before it passes you, and why its siren is still heard faintly well after the ambulance is out of sight? What you are witnessing is a scientific phenomenon known as the Doppler Effect. What takes place is truly remarkable. In both of these instances, when the train or ambulance moves toward the sound waves in front of it, the sound waves are pulled closer together and have a higher frequency. In either instance, the listener positioned in front of the moving object hears a higher pitch. The ambulance and locomotive are progressively moving away from the sound waves behind them, causing the waves to be farther apart and to have a lower frequency. These fast-approaching modes of transportation distance themselves past the listener, who hears a lower pitch.

Question 5:

What is the author’s primary purpose in discussing the Doppler Effect in this essay?

  • A: To entertain the reader with information about trains and ambulances
  • B: To inform the reader about avoiding accidents involving trains and ambulances
  • C: To inform the reader about how movement affects sound
  • D: To analyze the difference between train and ambulance sounds
  • Correct Answer: C

  • Rationale: The author's primary purpose in writing the essay about the Doppler Effect is to inform the reader about how movement affects sound. The essay explains the scientific phenomenon of the Doppler Effect and how it influences the perception of sound when objects like trains and ambulances are in motion. The focus is on how the movement of these objects toward or away from the listener alters the frequency and pitch of the sound waves. The essay aims to educate the reader on this specific aspect of physics rather than entertain or analyze differences between train and ambulance sounds.

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