Have you ever wondered why the whistle of a traveling, distant locomotive predicts its approach several yards before anyone actually ... [Show More] 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.
1. 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.
2. What is the main idea of the passage?
A. Trains and ambulances make distinctly loud noises.
B. Low-frequency waves make high-pitched sounds.
C. High-frequency waves make low-pitched sounds.
D. The Doppler effect explains the rationale for why sound is heard initially more strongly and then faintly after a moving object has passed.
3. 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
4. What is the author’s primary purpose in writing this essay?
A. To entertain the reader with information about trains and ambulances
B. To inform the reader about avoiding accidents, which involve trains and ambulances
C. To inform the reader about how movement affects sound
D. To analyze the difference between train and ambulance sounds
5. Which sound waves have a higher pitch?
A. Those waves that are closer together
B. Those waves that are farther apart
C. Those waves that travel a long distance
D. Those waves that travel a short distance
6. Which sound waves have a lower pitch?
A. Those waves that are closer together
B. Those waves that are farther apart
C. Those waves that travel a long distance
D. Those waves that travel a short distance
Beep!…Beep!…Beep! is the audible rhythmic sound made as the strength of the heart muscle is measured. The signal cadence has a characteristic record that varies in every individual. This record is called an electrocardiogram, or ECG.
In the body, an array of systemic neural responses constantly occur, emitting electric currents. The electric currents can be detected on the surface of the body, and if a person is hooked to an amplifier, these impulses are recorded by an electrocardiograph.
Most of the information obtained is about the heart because the heart sends out electric currents in waves. This “wave of excitation” spreads through the heart wall and is accompanied by electric changes. The wave takes place in three distinct steps.
Initially, the “wave of excitation” accompanied by an electric change lasts for approximately 1 to 2 seconds after the contraction of the cardiac muscle. The electric impulses are discharged rhythmically from the sinoatrial (SA) node, the pacemaker of the heart. This spread of excitation over the muscle of the atrium indicates that the atrium has contracted.
Next, the peak of the ECG reading is due to the atrioventricular (AV) node, causing the ventricle to become excited.
Finally, the ventricles relax, and any changes in the wave indicate to trained medical staff any abnormalities within the heart.
7. What is the author’s primary purpose in writing the essay?
A. To persuade the reader to have an ECG
B. To entertain the reader with a heart-warming story
C. To inform the reader how an electrocardiograph reads the electric currents emitted by the heart
D. To analyze the difference in the SA node and the AV node
8. Which statement is not listed as a detail within the passage?
A. Changes in the ECG are typically used for 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.
9. What is the meaning of the word emitting as it is used in the second paragraph?
10. What is the main idea of the passage?
A. Electric currents within the body are due to electrostatic charges set off by the heart.
B. The ECG systematically and quickly measures the stages at which the “wave of excitation” occurs within the heart and records them.
C. The “wave of excitation” is detected on the surface of the body and is used to measure the atrial excitation of the heart.
D. The electric currents within the body are in direct relation to the “wave of excitation” measured by the ECG.
11. 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.
12. What are the three steps of the “wave of excitation”?
A. The discharge from the SA node, the peak ECG, and the excitement of the ventricle.
B. The excitement of the ventricle, the relaxing of the ventricle, and the systemic neural response.
C. The contraction of the atrium, the relaxation of the atrium, and the contraction of the ventricle.
D. The excitation of the atrium, the excitement of the ventricle, and the relaxing of the ventricle.
The body is composed of systems that have evolved and diversified in order to maintain the natural functions and processes they regulate. One such system that has these regulators is the body’s cardiovascular system. The body’s pump, which regulates the flow of vitally needed oxygen to all cells of the body, as well as the discard of carbon dioxide and other waste products, is the heart.
Because blood pressure varies at different points within the body, differing components are needed to keep the body’s blood pressure regulated. Three of the basic components are baroreceptors, chemoreceptors, and the kidneys.
Baroreceptors are stretch receptors composed of fine branching nerve endings and are contained along the walls of the arteries near the heart and in other areas of the body as well. Impulses are related to this stretching along the arterial walls, which causes these baroreceptors to send out even more impulses to the heart, arteries, and veins, causing the blood pressure to go either up or down.
Chemoreceptors are located along the walls of the arteries and monitor changes in oxygen level, carbon dioxide, and pH. Just think! A fall in oxygen causes receptors to send impulses to raise the blood pressure.
The kidneys play a role in regulating blood pressure by absorbing salts and water and removing wastes. Hormones secreted by the adrenal cortex cause the kidney to keep or let go of any salt and water. This has an influence on blood volume and consequently on blood pressure.
13. What is the main idea of the passage?
A. Blood pressure can be treated only by monitoring baroreceptors.
B. Blood pressure can be treated only by monitoring chemoreceptors.
C. Blood pressure can be treated only by monitoring the kidneys.
D. Blood pressure can be regulated through baroreceptors, chemoreceptors, and the kidneys.
14. Which statement is not a detail from the passage?
A. Baroreceptors are rigid and static nerve endings that are contained along the arterial walls and send out messages along the nerve pathway.
B. Chemoreceptors are located along the walls of the arteries and monitor changes in oxygen level.
C. The kidneys play a role in regulating blood pressure by absorbing salts and water.
D. The heart is the body’s pump, which regulates the flow of vitally needed oxygen to cells of the body.
15. What is the meaning of the word evolved in the first paragraph?
A. To spread
B. To gradually develop
C. To revolve
D. To shift
16. What is the writer’s primary purpose in writing this essay?
A. To inform the reader about the dangers of high blood pressure
B. To inform the reader how high blood pressure leads to a higher risk of heart attack
C. To inform the reader how the cardiovascular system regulates blood pressure
D. To persuade the reader that controlling one’s blood pressure is important
17. What is the best summary of this passage?
A. The body’s pump, the heart, regulates the flow of oxygen to all cells of the body and discards waste products that include carbon dioxide. The kidneys help in this process by absorbing salts and water.
B. There are several systems to maintain the natural functions and processes of the body. One system is the cardiovascular system, which regulates blood pressure through baroreceptors, chemoreceptors, and the kidneys.
C. Baroreceptors help regulate blood pressure and are found along the wall of the arteries. Baroreceptors send out impulses to the heart, arteries, and veins, resulting in the lowering or raising of blood pressure.
D. Chemoreceptors monitor changes in oxygen level that affect blood pressure.
18. What is a major difference in the way baroreceptors and chemoreceptors work from the way the kidneys work?
A. Baroreceptors and chemoreceptors both work within the wall of the arteries sending out impulses to raise or lower blood pressure, whereas the kidneys help 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.
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.
19. What is the main idea of the passage?
A. Scientists fully understand the immune system.
B. The immune system triggers the production of fluids.
C. The body is under constant invasion by malicious microbes.
D. The immune system protects the body from infection.
20. Which statement is not a detail from the passage?
A. Most invaders of the body are microbes.
B. The immune system relies on excellent communication.
C. Viruses are extremely sophisticated.
D. The cells of the immune system are organized.
21. What is the meaning of the word ideal as it is used in the first paragraph?
22. Which statement is not a detail from the passage?
A. Scientists can now see T cells.
B. The immune system ignores tumors.
C. The ability of the immune system to fight disease without harming the body remains mysterious.
D. The immune system remembers millions of different invaders.
23. 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
24. What is the author’s primary purpose in writing the essay?
A. to persuade
B. to analyze
C. to inform
D. to entertain
The federal government regulates dietary supplements through the United States Food and Drug Administration (FDA). The regulations for dietary supplements are not the same as those for prescription or over-the-counter drugs. In general, the regulations for dietary supplements are less strict.
To begin with, a manufacturer does not have to prove the safety and effectiveness of a dietary supplement before it is marketed. A manufacturer is permitted to say that a dietary supplement addresses a nutrient deficiency, supports health, or is linked to a particular body function (such as immunity), if there is research to support the claim. Such a claim must be followed by the words “This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.”
Also, manufacturers are expected to follow certain good manufacturing practices (GMPs) to ensure that dietary supplements are processed consistently and meet quality standards.
Requirements for GMPs went into effect in 2008 for large manufacturers and are being phased in for small manufacturers through 2010.
Once a dietary supplement is on the market, the FDA monitors safety and product information, such as label claims and package inserts. If it finds a product to be unsafe, it can take action against the manufacturer and/or distributor and may issue a warning or require that the product be removed from the marketplace. The Federal Trade Commission (FTC) is responsible for regulating product advertising; it requires that all information be truthful and not misleading.
The federal government has taken legal action against a number of dietary supplement promoters or Web sites that promote or sell dietary supplements because they have made false or deceptive statements about their products or because marketed products have proven to be unsafe.
25. What is the main idea of the passage?
A. Manufacturers of dietary supplements have to follow good manufacturing practices.
B. The FDA has a special program for regulating dietary supplements.
C. The federal government prosecutes those who mislead the general public.
D. The FDA is part of the federal government.
26. Which statement is not a detail from the passage?
A. Promoters of dietary supplements can make any claims that are supported by research.
B. GMP requirements for large manufacturers went into effect in 2008.
C. Product advertising is regulated by the FTC.
D. The FDA does not monitor products after they enter the market.
27. What is the meaning of the phrase phased in as it is used in the third paragraph?
A. stunned into silence
C. implemented in stages
D. legalized [Show Less]