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TOEFL Experts Reading Practice 9

Reading Section

This section measures your ability to understand academic passages in English. You can skip questions and go back to them later as long as there is time remaining.

Now begin the Reading section.

Reading Section

This section measures your ability to understand academic passages in English. You can skip questions and go back to them later as long as there is time remaining.

Now begin the Reading section.

Lead in Gasoline (Petrol)

The element lead is a heavy, soft metal that has been known since ancient times to be poisonous in large quantities. More recently, it has been recognized that even low exposure to lead causes biological damage over long periods of time. For decades in the twentieth century, however, nearly every automobile produced exhaust laced with lead.

In the body, lead causes widespread damage by interfering with many enzymes (proteins that enable biological processes). The typical ion, or charged atomic form, of lead easily replaces calcium, iron, and zinc ions, which are necessary components of these enzymes. Lead ions are imperfect replacements, so the enzymes fail to function properly. Lead particularly damages the central nervous system, impeding the proper growth and working of brain cells. The element also displaces calcium in bone tissue, providing a reservoir for lead to reenter the rest of the body even when outside sources are removed. Children are particularly vulnerable to harm from lead exposure and can be impaired cognitively and behaviorally for life.

Easy to find, mine, and refine, lead has been in use for thousands of years. The word “plumbing” comes from plumbum, the Latin word for lead, because the ancient Romans ran drinking water through pipes made of the metal. Lead is now a crucial component of car batteries, radiation shields, and ammunition. The two forms of lead that have contributed the most to human exposure, however, are lead paint and tetraethyl lead (TEL), a gasoline additive that prevents a problem called engine knock.

Internal combustion engines depend upon the smooth burning of mixtures of fuel and air, so that the pistons inside the engines are driven in a steady way. When these mixtures ignite prematurely, however, unintended shock waves damage the pistons and other engine parts. This phenomenon is labeled “engine knock” for the loud metallic pinging that accompanies the shock waves. Engine knock is suppressed by changing the composition of the fuel itself or by adding other chemicals. Early automobile engines that ran on petroleum-based fuel suffered greatly from engine knock, because it was difficult and expensive to alter the makeup of the fuel itself to eliminate this issue.

Without the discovery of TEL’s “antiknock” capabilities, automobiles may have had to run on non-petroleum-based fuel, such as ethanol. However, in 1919, TEL was identified as a potent additive to gasoline that eliminated knock and further lubricated engine valves. The United States oil industry quickly began to manufacture TEL and promote it as a means of improving both power and fuel economy in automobiles. Rapid expansion of industrial production of the additive resulted in several lethal accidents, as unprotected chemical plant workers were poisoned by contact with TEL. After a conference called by the chief United States health official, however, TEL was approved for countrywide use. Soon, automobiles in the United States and elsewhere were running almost exclusively on leaded gasoline.

In the late 1940s, geologist Clair Patterson analyzed the radioactive decay of uranium into lead in terrestrial rocks, as well as in meteorites, in order to determine the age of the Earth. In these investigations, however, Patterson had to overcome contamination resulting from lead pollution. The focus of his subsequent research was to show how widespread this contamination was and to advocate for restrictions on the use of TEL. His advocacy, as well as that of other scientists, was resisted by supporters of the lead and automobile industries. Under pressure to reduce general air pollution created by automobiles, however, manufacturers announced in the early 1970s that antipollution devices called catalytic converters would be installed on new cars. Since these devices would be ruined by lead, the use of TEL was to be phased out.

By 1986, the use of lead gasoline additives in the United States was prohibited. Since then, sharp reductions in blood-lead levels in the population have been observed, along with other improvements in public health. Nevertheless, TEL is still used in automobiles in a few countries, as well as in “avgas” (aviation gasoline) that fuels propeller airplanes around the world. In addition, the blanket of lead particles deposited globally by prior combustion of leaded gasoline will pose an environmental hazard for many years to come.

Lead in Gasoline (Petrol)

→(P1) The element lead is a heavy, soft metal that has been known since ancient times to be poisonous in large quantities. More recently, it has been recognized that even low exposure to lead causes biological damage over long periods of time. For decades in the twentieth century, however, nearly every automobile produced exhaust laced with lead.

Q: The word “laced with” in paragraph 1 is closest in meaning to

Improved by

Deprived of

Mixed with

Obtained from

→(P2) In the body, lead causes widespread damage by interfering with many enzymes (proteins that enable biological processes). The typical ion, or charged atomic form, of lead easily replaces calcium, iron, and zinc ions, which are necessary components of these enzymes. Lead ions are imperfect replacements, so the enzymes fail to function properly. Lead particularly damages the central nervous system, impeding the proper growth and working of brain cells. The element also displaces calcium in bone tissue, providing a reservoir for lead to reenter the rest of the body even when outside sources are removed. Children are particularly vulnerable to harm from lead exposure and can be impaired cognitively and behaviorally for life.

Q: In paragraph 2, the author indicates that enzymes in the body do not work correctly when they contain lead ions because

Lead ions easily replace calcium, iron, and zinc ions

Calcium, iron, and zinc ions are necessary components of the enzymes

Lead ions are flawed substitutes for calcium, iron, and zinc ions

Lead ions cause particular damage to the central nervous system

→(P2) In the body, lead causes widespread damage by interfering with many enzymes (proteins that enable biological processes). The typical ion, or charged atomic form, of lead easily replaces calcium, iron, and zinc ions, which are necessary components of these enzymes. Lead ions are imperfect replacements, so the enzymes fail to function properly. Lead particularly damages the central nervous system, impeding the proper growth and working of brain cells. The element also displaces calcium in bone tissue, providing a reservoir for lead to reenter the rest of the body even when outside sources are removed. Children are particularly vulnerable to harm from lead exposure and can be impaired cognitively and behaviorally for life.

Q: Why does the author mention a “reservoir” in paragraph 2?

To describe how lead could be re-released in the body

To illustrate how lead displaces calcium in bone tissue

To support the point that lead impedes the proper working of cells

To provide an example of a location where lead is replaced by calcium ions

→(P3) Easy to find, mine, and refine, lead has been in use for thousands of years. The word “plumbing” comes from plumbum, the Latin word for lead, because the ancient Romans ran drinking water through pipes made of the metal. Lead is now a crucial component of car batteries, radiation shields, and ammunition. The two forms of lead that have contributed the most to human exposure, however, are lead paint and tetraethyl lead (TEL), a gasoline additive that prevents a problem called engine knock.

Q: Which of the sentences below best expresses the essential information in the highlighted sentence in paragraph 3? Incorrect choices change the meaning in important ways or leave out essential information.

Tetraethyl lead, which is added to gasoline to prevent engine knock, contributes more than lead paint to human exposure.

As a result of its anti-knock properties, the gasoline additive tetraethyl lead is the form of lead that contributes the most to human exposure.

A gas oline additive and lead paint have contributed to human exposure to lead.

Lead paint and a gas oline additive have contributed more to human exposure than any other forms of lead.

→(P4) Internal combustion engines depend upon the smooth burning of mixtures of fuel and air, so that the pistons inside the engines are driven in a steady way. When these mixtures ignite prematurely, however, unintended shock waves damage the pistons and other engine parts. This phenomenon is labeled “engine knock” for the loud metallic pinging that accompanies the shock waves. Engine knock is suppressed by changing the composition of the fuel itself or by adding other chemicals. Early automobile engines that ran on petroleum-based fuel suffered greatly from engine knock, because it was difficult and expensive to alter the makeup of the fuel itself to eliminate this issue.

Q: The word “prematurely” in the passage is closest in meaning to

Violently

Early

Unevenly

Belatedly

→(P4) Internal combustion engines depend upon the smooth burning of mixtures of fuel and air, so that the pistons inside the engines are driven in a steady way. When these mixtures ignite prematurely, however, unintended shock waves damage the pistons and other engine parts. This phenomenon is labeled “engine knock” for the loud metallic pinging that accompanies the shock waves. Engine knock is suppressed by changing the composition of the fuel itself or by adding other chemicals. Early automobile engines that ran on petroleum-based fuel suffered greatly from engine knock, because it was difficult and expensive to alter the makeup of the fuel itself to eliminate this issue.

Q: It can be inferred from paragraph 4 that the primary reason to suppress engine knock is to

Reduce the harm to various engine parts

Muffle the loud metallic pings that result

Improve the composition of the engine’s fuel

Promote the ignition of fuel—air mixtures

→(P4) Internal combustion engines depend upon the smooth burning of mixtures of fuel and air, so that the pistons inside the engines are driven in a steady way. When these mixtures ignite prematurely, however, unintended shock waves damage the pistons and other engine parts. This phenomenon is labeled “engine knock” for the loud metallic pinging that accompanies the shock waves. Engine knock is suppressed by changing the composition of the fuel itself or by adding other chemicals. Early automobile engines that ran on petroleum-based fuel suffered greatly from engine knock, because it was difficult and expensive to alter the makeup of the fuel itself to eliminate this issue.

Q: The phrase “this issue” in the passage refers to

Engines running on petroleum-based fuel

Engines suffering from knock

The difficulty and expense of fuel alterations

The addition of other chemicals to the fuel

→(P5) Without the discovery of TEL’s “antiknock” capabilities, automobiles may have had to run on non-petroleum-based fuel, such as ethanol. However, in 1919, TEL was identified as a potent additive to gasoline that eliminated knock and further lubricated engine valves. The United States oil industry quickly began to manufacture TEL and promote it as a means of improving both power and fuel economy in automobiles. Rapid expansion of industrial production of the additive resulted in several lethal accidents, as unprotected chemical plant workers were poisoned by contact with TEL. After a conference called by the chief United States health official, however, TEL was approved for countrywide use. Soon, automobiles in the United States and elsewhere were running almost exclusively on leaded gasoline.

Q: When does paragraph 5 indicate that lethal accidents occurred in relation to other events described?

Before TEL was identified as a potent gasoline additive

After a conference that the chief United States health official called

Before the rapid expansion of industrial production of TEL

After the promotion of TEL as a way to improve automobile performance

Q: The phrase “almost exclusively” in the passage is closest in meaning to

Wholly and entirely

Hardly at all

Virtually privately

With few exceptions

→(P6) In the late 1940s, geologist Clair Patterson analyzed the radioactive decay of uranium into lead in terrestrial rocks, as well as in meteorites, in order to determine the age of the Earth. In these investigations, however, Patterson had to overcome contamination resulting from lead pollution. The focus of his subsequent research was to show how widespread this contamination was and to advocate for restrictions on the use of TEL. His advocacy, as well as that of other scientists, was resisted by supporters of the lead and automobile industries. Under pressure to reduce general air pollution created by automobiles, however, manufacturers announced in the early 1970s that antipollution devices called catalytic converters would be installed on new cars. Since these devices would be ruined by lead, the use of TEL was to be phased out.

Q: The word “subsequent” in the passage is closest in meaning to

Later

Minor

Prior

Principal

→(P6) In the late 1940s, geologist Clair Patterson analyzed the radioactive decay of uranium into lead in terrestrial rocks, as well as in meteorites, in order to determine the age of the Earth. In these investigations, however, Patterson had to overcome contamination resulting from lead pollution. The focus of his subsequent research was to show how widespread this contamination was and to advocate for restrictions on the use of TEL. His advocacy, as well as that of other scientists, was resisted by supporters of the lead and automobile industries. Under pressure to reduce general air pollution created by automobiles, however, manufacturers announced in the early 1970s that antipollution devices called catalytic converters would be installed on new cars. Since these devices would be ruined by lead, the use of TEL was to be phased out.

Q: Paragraph 6 mentions all of the following as true of the activities of geologist Clair Patterson EXCEPT:

Patterson examined the way uranium decayed in terrestrial rocks and meteorites.

Patterson confronted the problem of lead contamination caused by pollution.

Patterson advocated for resistance by supporters of the lead and automobile industries.

Patterson studied how geographically wide-ranging the lead contamination was.

→(P7) By 1986, the use of lead gasoline additives in the United States was prohibited. Since then, sharp reductions in blood-lead levels in the population have been observed, along with other improvements in public health. Nevertheless, TEL is still used in automobiles in a few countries, as well as in “avgas” (aviation gasoline) that fuels propeller airplanes around the world. In addition, the blanket of lead particles deposited globally by prior combustion of leaded gasoline will pose an environmental hazard for many years to come.

Q: Which of the following statements is best supported by the reports on the current use of TEL described in paragraph 7?

The continued worldwide presence of TEL in avgas makes differences in the use of TEL in automobile gasoline unimportant.

Blood-lead levels in countries where TEL is still used in automobiles are likely higher than in the United States.

Other improvements in public health have been observed in countries where TEL is still used in automobiles.

Avgas use does not contribute to the blanket of lead particles deposited globally by combustion of leaded gasoline.

In paragraph 2 and 3 of the passage, there is a missing sentence. The paragraph is repeated below and shows four letters [A], [B], [C], and [D] that indicate where the following sentence could be added.

Despite this potential for injury, the utilization of lead is widespread.

Where would the sentence best fit?

→(P2) Lead particularly damages the central nervous system, impeding the proper growth and working of brain cells. The element also displaces calcium in bone tissue, providing a reservoir for lead to reenter the rest of the body even when outside sources are removed. Children are particularly vulnerable to harm from lead exposure and can be impaired cognitively and behaviorally for life.

→(P3) [A] Easy to find, mine, and refine, lead has been in use for thousands of years. [B]The word “plumbing” comes from plumbum, the Latin word for lead, because the ancient Romans ran drinking water through pipes made of the metal.[C] Lead is now a crucial component of car batteries, radiation shields, and ammunition. [D]The two forms of lead that have contributed the most to human exposure, however, are lead paint and tetraethyl lead (TEL), a gasoline additive that prevents a problem called engine knock.

Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.

The poisonous metal lead was released by most cars for decades.

Lead is now a key component of car batteries, as well as of radiation shields and ammunition.

Tetraethyl lead prevents knock from damaging automobile engines.

Geologist Clair Patterson analyzed the radioactive decay of uranium into lead.

The use of leaded gasoline was finally phased out in the United States in order to reduce blood-lead levels.

Health improvements have occurred since the elimination of lead in United States gasoline, but dangers remain worldwide.

Lead causes injury throughout the human body in various ways and is especially harmful to children.

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