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TOEFL Reading 7

 

[1] Living organisms have an important function in the formation of soil. The numerous animals and plants that live in the soil use minerals found there, and in turn create organic matter that aids in the translocation (movement) and aeration of the soil, and helps protect the soil from erosion. Various types of organisms which dwell in the soil substantially influence the soil’s chemical and physical characteristics. In fact, for mature soils found around the world, this important type of natural growth is thought to have the greatest direct impact on soil characteristics. For this reason, a soil scientist can understand quite a bit about the attributes of the soil in any given place simply from understanding what sort of flora the soil supports. Thus prairies and tundra regions, which have characteristic vegetations, also have mature soils.

[2] The quantity and total weight of soil vegetation typically exceeds that of soil fauna. Far and away, the most common and smallest of the plants dwelling in the soil are bacteria. In favorable conditions, over a million of these tiny, single-celled plants can inhabit each cubic centimeter of soil. Beyond that of any other organism, bacteria allow rock or other parent material to undergo a gradual, yet regular transformation to the soil. Some microorganisms produce natural acids that immediately attack parent material, breaking it down and releasing plant nutrients. The second group of microorganisms decompose natural waste (debris) to shape humus (nutrient-rich organic matter). The third group of bacteria inhabits the root systems of flora called legumes. Included in this are many well-known agricultural crops, such as alfalfa, soybeans, peas, clover, and peanuts. Legumes host bacteria within their root nodules (small swellings on the root) that converts nitrogen gas from their surroundings into nitrogen compounds that flora is able to metabolize in a process known as nitrogen fixation, which results in more fertile soil.

[3] There are other life forms that play a vital role in soil development. For example, in rather acidic soils where few bacteria can survive, fungi frequently emerge as the main decomposers of organic matter. More complex varieties of vegetation are also essential to the development of the soil. Trees, grass and various other types of vegetation provide the bulk of the soil’s humus. The minerals released as these plants decompose make up an essential nutrient supply for succeeding generations of flora as for other soil organisms. In addition, timber can extend their roots deep within the soil and carry vitamins up from a long way under the surface. When the tree loses its leaves, or when it dies and decomposes, this will result in enrichment of the soil with vitamins. Finally, timber performs the indispensable function of slowing water runoff and keeping the soil in place with their root systems, consequently combating erosion. The increased erosion that often accompanies the agricultural use of sloping land is mainly induced by eliminating its protecting layer of natural vegetation.

[4] Animals also have an effect on soil composition. The faunal counterparts of bacteria are protozoa. These single-celled organisms are the most commonly found members of the animal kingdom, and, like bacteria, more than a million can inhabit each cubic centimeter of soil at a time. Protozoa feed on organic matter and hasten its decomposition. The earthworm is in all likelihood the most essential among the soil-dwelling inhabitants. Under fairly favorable conditions, up to a million earthworms (with total body weight exceeding about 450 kilograms) may inhabit an acre of soil. Earthworms ingest large quantities of soil, chemically alter it, and excrete it as organic matter called casts. The casts form an incredible natural fertilizer. In addition, earthworms mix soil both vertically and horizontally, improving aeration and drainage.

[5] Under favorable climatic and soil conditions, insects such as ants and termites may also be numerous. In addition, local mammals such as mice, gophers, moles and prairie dogs are occasionally present in sufficient numbers to have an enormous impact on the soil. These animals chiefly work the soil mechanically. As a result, the soil is aerated, broken up, fertilized, and brought to the surface, hastening soil development.

1 Which of the following best expresses the essential information in the highlighted sentence? Incorrect answer choices change the meaning in important ways or leave out essential information.

Legumes host bacteria within their root nodules (small swellings on the root) that converts nitrogen gas from the surroundings into nitrogen compounds that flora is able to metabolize in a process known as nitrogen fixation, which results in more fertile soil.

  • Legumes make the soil extra fertile by using internet hosting of microorganisms in their root nodules.
  • Nitrogen fixation makes compounds that flowers and microorganisms metabolize in legumes.
  • Bacteria residing in the roots of legumes make the soil more fertile by producing nitrogen compounds that vegetation can metabolize.
  • The root nodules of legumes contain bacteria, nitrogen gasoline from the atmosphere, and nitrogen compounds that plant life can metabolize.

ANSWER EXPLANATION

Question is worth: 1 point.

Correct Answer: c
Your Selection: Not Answered

C is the correct answer because it correctly expresses the meaning of the highlighted sentence.

A is incorrect because internet hosting is not mentioned in the passage.
B is incorrect because Nitrogen fixation is the result of converting nitrogen gas.
D is incorrect because legumes do not contain nitrogen gasoline.

2 According to paragraph 2, which of the following statements about soil creation is true?

  • Soil creation takes place when a cubic centimeter of subsisting soil incorporates abundant natural material.
  • Soil creation requires that there be a greater amount of flora than fauna in any given location.
  • The soil is created as a result of bacteria breaking down rocks and organic material.
  • The soil is created from the organic particles left over when microorganisms decay.

ANSWER EXPLANATION

Question is worth: 1 point.

Correct Answer: c
Your Selection: Not Answered

C is the correct answer because the following sentence supports it form paragraph 2

"In favorable conditions, over a million of these tiny, single-celled plants can inhabit each cubic centimeter of soil. Beyond that of any other organism, bacteria allow rock or other parent material to undergo a gradual, yet regular transformation to the soil."

A is incorrect because the measurement of soil is not related to soil creation.
B is incorrect because there are more fauna than flora. The paragraph just mentions that the flora outweigh the fauna.
D is incorrect because decay is the result of breaking down organic material.

3 In paragraph 3, why does the author mention the activity of fungi in acidic soils?

  • To show that fungi have the capability of organic matter in extreme conditions.
  • To exhibit that fungi play a different role from bacteria in decaying organic matter.
  • To demonstrate the varieties of life that help support soil development.
  • To account for the survival of microscopic plants in acidic soils.

ANSWER EXPLANATION

Question is worth: 1 point.

Correct Answer: c
Your Selection: Not Answered

C is the correct answer because the main topic of paragraph 3 is acid soils and how soil development is created in it without bacteria due to the bacteria not being able to survive.

A is incorrect because it is a minor detail in the paragraph.
B is incorrect fungi play the same role as bacteria.
D is incorrect because survival is not the topic of paragraph 3.

4 According to paragraph 3, how will trees benefit other plants?

  • When trees die and decay, they make available a large amount of space for generations of different plants to grow.
  • When timber decomposes, they release nutrient minerals deep into the soil.
  • Trees make nutrients available to plants whose roots do not extend deeper into the soil.
  • Humus from timber provides essential vitamins for plants with roots that grow deep within the soil.

ANSWER EXPLANATION

Question is worth: 1 point.

Correct Answer: c
Your Selection: Not Answered

C is the correct answer because it is stated that timber roots reach a far way down and can bring vitamins up, in addition to, when a tree losses it's leaves or decomposes it provides enrichment,

A is incorrect because space from decay is not mentioned.
B is incorrect because it is not mentioned that timber releases nutrients deep within the soil, but actually, brings up the nutrients.
D is incorrect because there is no mention of plants that grow roots deep within the soil.

5 According to paragraph 3, what can be inferred about the impact of vegetation on soil?

  • The root systems of most crops are unable to prevent erosion on sloping ground.
  • The roots of trees and other big plants remove water from the ground, making the soil dry and likely to be affected by the wind.
  • Areas that naturally have little vegetation, such as deserts, are more easily eroded than agricultural land that has been cleared of its natural vegetation.
  • Without a cover of vegetation, fast running water is likely to vanish from the ground surface before it can erode much of the soil.

ANSWER EXPLANATION

Question is worth: 1 point.

Correct Answer: a
Your Selection: Not Answered

A is the correct answer because it can be inferred that because timber so indispensably keeps the soil in place with their root systems, that other crops cannot do this.

B is incorrect because making the soil dry is not mentioned.
C is incorrect because deserts are not mentioned.
D is incorrect because its the timber's roots that help with keeping the soil in place and not the cover of vegetation.

6 According to paragraph 4, earthworms do the following to help soils develop EXCEPT

  • generate a natural fertilizer
  • modify the chemistry of the soil
  • combine the soil in different directions
  • consume waste matter

ANSWER EXPLANATION

Question is worth: 1 point.

Correct Answer: d
Your Selection: Not Answered

D is the correct answer because earthworms create waste matter.

"Earthworms ingest large quantities of soil, chemically alter it, and excrete it as organic matter called casts."

Excrete means to release, so the earthworms are releasing organic matter.

A, B, and C are all mentioned in paragraph 4 as something the earthworms do.

7 The word 'numerous' in paragraph 5 is closest in meaning to:

  • little
  • slightly
  • meagerly
  • countless

ANSWER EXPLANATION

Question is worth: 1 point.

Correct Answer: d
Your Selection: Not Answered

D is the correct answer because it is the closest in meaning to numerous.

Numerous: great in number
Countless: to many to count.

A means small
B means to do something carefully or partly correct
C means deficient in quantity or quality; lacking fullness or richness; scanty; inadequate:

8 According to paragraph 5, in which of the following ways do some mammals help soils develop?

  • They abolish waste matter that would otherwise pollute the soil
  • They prevent insects from feeding on nutrients that enhance the soil
  • They break up the soil as they move through it.
  • They make sure that fertilizer remains in the soil.

ANSWER EXPLANATION

Question is worth: 1 point.

Correct Answer: c
Your Selection: Not Answered

C is the correct answer because it is mentioned in paragraph 5

"local mammals such as mice, gophers, moles and prairie dogs are occasionally present in sufficient numbers to have an enormous impact on the soil. These animals chiefly work the soil mechanically. As a result, the soil is aerated, broken up, fertilized, and brought to the surface, hastening soil development."

A is incorrect because abolishing water was not mentioned.
B is incorrect because insects help the soul.
D is incorrect because they help fertilize, not make sure it remains.

9 Examine the four █ in the selection below and indicate at which block the following sentence could be inserted into the passage:


Nutrients obtained by these deep roots nourish the trees and are preserved within them.

 

More complex varieties of vegetation are also essential to the development of the soil. █ [A] Trees, grass and various other types of vegetation provide the bulk of the soil’s humus. █ [B] The minerals released as these plants decompose make up an essential nutrient supply for succeeding generations of flora as for other soil organisms. █ [C] In addition, timber can extend their roots deep within the soil and carry vitamins up from a long way under the surface. █ [D] When the tree loses its leaves, or when it dies and decomposes, this will result in enrichment of the soil with vitamins. Finally, timber performs the indispensable function of slowing water runoff and keeping the soil in place with their root systems, consequently combating erosion..

  • [A]
  • [B]
  • [C]
  • [D]

ANSWER EXPLANATION

Question is worth: 1 point.

Correct Answer: d
Your Selection: Not Answered

D is the correct answer because the sentence before D introduces the deep roots and the fact they carry vitamins up a far way. it makes sense to now mention that these deeps roots nourish the trees with the nutrients they bring up.

The remaining options do not make logical sense and so are incorrect.

10Directions: 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.

Drag your answer choices to the spaces where they belong. To remove an answer choice, drag it back. To review the passage, click VIEW TEXT.

 

Plants and animals play an important role in the development of soils.

  • B. Trees and other large flora contribute to soil improvement by creating fertilizer as they decompose, and by means of defending the soil against erosion.
  • C. Earthworms, protozoa, and small mammals make a contribution to soil improvement via oxygenated, fertilizing, and mixing the soil.
  • F. Small organisms such as fungi and bacteria create and enhance the soil by means of breaking down rocks and organic matter

 

  • A. Agricultural crops such as clover, alfalfa, peas, soybeans, and peanuts give nutrient minerals to the soil as they die and decay
  • B. Trees and other large flora contribute to soil improvement by creating fertilizer as they decompose, and by means of defending the soil against erosion.
  • C. Earthworms, protozoa, and small mammals make a contribution to soil improvement via oxygenated, fertilizing, and mixing the soil.
  • D. Soil in places like prairies and tundras can be found in areas where prerequisites are usually not favorable for soil development.
  • E. Certain animals block soil development via digging big holes in the floor that prevent vitamins from attaining some areas of the soil.
  • F. Small organisms such as fungi and bacteria create and enhance the soil by means of breaking down rocks and organic matter

ANSWER EXPLANATION

Question is worth: 2 points.

Correct Answer: b,c,f
Your Selection: Not Answered

B, C, and F are the correct answers because they are all the main points in the various paragraphs.

A is only a minor detail made in paragraph 2.
D is an incorrect statement not mentioned in the passage.
E is an incorrect statement not mentioned in the passage.

 

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