Official22托福阅读Passage1 Spartina 文本+题目原文+答案解析【雷哥托福】2019-02-21 10:03:43 发布 来源：雷哥托福 阅读量:3390
TPO22托福阅读Passage1 Spartina 文本+题目原文+答案解析
Spartina alterniflora, known as cordgrass, is a deciduous, perennial flowering plant native to the Atlantic coast and the Gulf Coast of the United States. It is the dominant native species of the lower salt marshes along these coasts, where it grows in the intertidal zone (the area covered by water some parts of the day and exposed others).
These natural salt marshes are among the most productive habitats in the marine environment. Nutrient-rich water is brought to the wetlands during each high tide, making a high rate of food production possible. As the seaweed and marsh grass leaves die, bacteria break down the plant material, and insects, small shrimplike organisms, fiddler crabs, and marsh snails eat the decaying plant tissue, digest it, and excrete wastes high in nutrients. Numerous insects occupy the marsh, feeding on living or dead cordgrass tissue, and redwing blackbirds, sparrows, rodents, rabbits, and deer feed directly on the cordgrass. Each tidal cycle carries plant material into the offshore water to be used by the subtidal organisms.
Spartina is an exceedingly competitive plant. Ⓐ It spreads primarily by underground stems; colonies form when pieces of the root system or whole plants float into an area and take root or when seeds float into a suitable area and germinate. ⒷSpartina establishes itself on substrates ranging from sand and silt to gravel and cobble and is tolerant of salinities ranging from that of near freshwater (0.05 percent) to that of salt water (3.5 percent). Ⓒ Because they lack oxygen, marsh sediments are high in sulfides that are toxic to most plants. ⒹSpartina has the ability to take up sulfides and convert them to sulfate, a form of sulfur that the plant can use; this ability makes it easier for the grass to colonize marsh environments. Another adaptive advantage is Spartina’s ability to use carbon dioxide more efficiently than most other plants.
These characteristics make Spartina a valuable component of the estuaries where it occurs naturally. The plant functions as a stabilizer and a sediment trap and as a nursery area for estuarine fish and shellfish. Once established, a stand of Spartina begins to trap sediment, changing the substrate elevation, and eventually the stand evolves into a high marsh system where Spartina is gradually displaced by higher-elevation, brackish-water species. As elevation increases, narrow, deep channels of water form throughout the marsh. Along the east coast Spartina is considered valuable for its ability to prevent erosion and marshland deterioration; it is also used for coastal restoration projects and the creation of new wetland sites.
Spartina was transported to Washington State in packing materials for oysters transplanted from the east coast in 1894. Leaving its insect predators behind, the cordgrass has been spreading slowly and steadily along Washington’s tidal estuaries on the west coast, crowding out the native plants and drastically altering the landscape by trapping sediment. Spartina modifies tidal mudflats, turning them into high marshes inhospitable to the many fish and waterfowl that depend on the mudflats. It is already hampering the oyster harvest and the Dungeness crab fishery, and it interferes with the recreational use of beaches and waterfronts. Spartina has been transplanted to England and to New Zealand for land reclamation and shoreline stabilization. In New Zealand the plant has spread rapidly, changing mudflats with marshy fringes to extensive salt meadows and reducing the number and kinds of birds and animals that use the marsh.
Efforts to control Spartina outside its natural environment have included burning, flooding, shading plants with black canvas or plastic, smothering the plants with dredged materials or clay, applying herbicide, and mowing repeatedly. Little success has been reported in New Zealand and England; Washington State’s management program has tried many of these methods and is presently using the herbicide glyphosphate to control its spread. Work has begun to determine the feasibility of using insects as biological controls, but effective biological controls are considered years away. Even with a massive effort, it is doubtful that complete eradication of Spartina from nonnative habitats is possible, for it has become an integral part of these shorelines and estuaries during the last 100 to 200 years.
TPO22 托福阅读 Passage1 Spartina 题目
Question 1 of 14: According to paragraph 1, each of the following is true of Spartina alrerniflora EXCEPT:
A. It rarely flowers in salt marshes.
B. It grows well in intertidal zones.
C. It is commonly referred to as cordgrass.
D. It occurs naturally along the Gulf Coast and the Atlantic coast of the United States.
Question 2 of 14: According to paragraph 2, a major reason why natural salt marshes are so productive is that they are
A. inhabited by long-lived seaweed and marsh grasses that reproduce gradually
B. kept clear of excess plant material by the tides
C. regularly supplied with high levels of nutrients
D. home to a wide variety of different species of grasses
Question 3 of 14: Which of the sentences below best express the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
A. Insects feed only on dead cordgrass, while most other marsh inhabitants feed on live cordgrass.
B. The marsh is a good habitat for insects, but a relatively poor one for birds and animals.
C. Although cordgrass provides food for birds and animals, it gives insects both food and a place to live.
D. Cordgrass provides food for numerous insects, birds, and other animals.
Question 4 of 14: What is the organizational structure of paragraph 3?
A. It makes a general claim about Spartina and then provides specific evidence to defend that claim against objections to the claim.
B. It presents a general characterization of Spartina and then describes particular features on which this characterization is based.
C. It reports a widely held view about Spartina and then considers evidence both for and against that view.
D. It presents a general hypothesis about Spartina and then lists specific evidence that disputes that hypothesis.
Question 5 of 14: The word "exceedingly" in the passage is closest in meaning to
Question 6 of 14: According to paragraph 3, one reason that Spanina is able to compete in marsh environments so successfully is its ability to
A. alter the substrate in which it grows
B. convert sulfides into a usable form of sulfur
C. grow and produce seeds while floating on the surface of the water
D. produce carbon dioxide with great efficiency
Question 7 of 14: Paragraph 4 suggests that where Spanina occurs naturally, an established stand of it will eventually
A. create conditions in which it can no longer survive
B. get washed away by water flowing through the deep channels that form around it
C. become adapted to brackish water
D. take over other grass species growing in the area
Question 8 of 14: According to paragraph 4, in its natural habitats, Spanina helps estuaries by
A. controlling marshland decline
B. decreasing the substrate elevation
C. reducing the brackishness of the water
D. increasing the flow of water into the estuary
Question 9 of 14: According to paragraph 5, Spanina negatively affects wildlife in estuaries by
A. trapping fish and waterfowl in sediment
B. preventing oysters from transplanting successfully
C. turning mudflats into high marshes and salt meadows
D. expanding the marshy fringes of salt meadows
Question10 of 14: The word "modifies" in the passage is closest in meaning to
C. grows on
D. breaks down
Question11 of 14: According to paragraph 6, each of the following methods has been used in attempts to control Spanina EXCEPT
A. flooding plants
B. cutting plants down repeatedly
C. applying herbicides
D. introducing predatory insects
Question 12 of 14: The word "Efforts" in the passage is closest in meaning to
Question13 of 14: Look at the four squares [Ⓐ] [Ⓑ] [Ⓒ] and [Ⓓ] that indicate where the following sentence could be added to the passage.
Spartina is particularly able to tolerate high salinities because salt glands on the surface of the leaves remove the salt from the plant sap.
Where would the sentence best fit?
A. It spreads primarily by underground stems; colonies form when pieces of the root system or whole plants float into an area and take root or when seeds float into a suitable area and germinate.
B. Spartina establishes itself on substrates ranging from sand and silt to gravel and cobble and is tolerant of salinities ranging from that of near freshwater (0.05 percent) to that of salt water (3.5 percent).
C. Because they lack oxygen, marsh sediments are high in sulfides that are toxic to most plants.
D. Spartina has the ability to take up sulfides and convert them to sulfate, a form of sulfur that the plant can use; this ability makes it easier for the grass to colonize marsh environments.
Question14 of 14: Spanina alrerniflora, or cordgrass, is the dominant native species in salt marshes along the Atlantic coast and the Gulf Coast of the United States.
Click on 3 answers.
A. Spartina is very well adapted to conditions in salt marshes, where it plays a valuable role in stabilizing them and making them highly productive marine habitats.
B. Spartina expands by growing root systems that float on the water’s surface and descend underground, where it finds the nutrients that it needs to germinate.
C. As a result of its spread in Washington State over the past hundred years. Spartina has now become a threat to native oysters by releasing sediments that contain sulfides into the waters.
D. The dead leaves of Spartina become food for a wide variety of marine organisms.
E. Outside its native regions, Spartina can pose serious problems by turning mudflats into high marshes that are inhospitable to many native fish and birds.
F．Spartina has physiological adaptations that allow it to grow in environments where other plants cannot, making it a very strong competitor that is difficult to control once it is established.
TPO22托福阅读Passage1 Spartina 真题解析
Question 1 of 14
解析：此题可以采用排除法。A的salt marshes做关键词定位至第二句，但这句没提到是否开花的信息，第一句提到spartina是perennial flowering plant，而A说不开花，所以A与原文相反，选；B的intertidal zone做关键词同样定位至第二句，正确，不选；C的cordgrass做关键词定位至首句，提到spartina也叫cordgrass，正确，不选；D的Gulf Coast做关键词定位至首句，正确，不选。正确答案是A。
Question 2 of 14
解析：以salt marshes are so productive做关键词定位至第二句，提到富营养的水被潮水带到marsh，导致生产率很高，所以正确答案是C。其他答案都未提及。
Question 3 of 14
解析：原文的结构是insects和很多其他的动物都吃cordgrass，所以正确答案是D。A的only dead cordgrass与原文相反；B的habitat和C的a place to live都未提及。
Question 4 of 14
Question 5 of 14
Question 6 of 14
解析：以marsh environments做关键词定位至倒数第二句，提到spartina能够吸收sulfide并将其转化为sulfate，这一能力使得spartina能够占领marsh environments，所以正确答案是B，A的“改变”substrate，C的floating on the surface和D的produce carbon dioxide都未提到。
Question 7 of 14
解析：以established stand做关键词定位至第三句，提及一旦establish之后，spartina会做一些事情，stand变成high marsh system，spartina会被替代，所以正确答案是A的no longer survive。B的get washed，C的adapt和D的take over都未提及。
Question 8 of 14
解析：整段都在叙述spartina如何帮忙estuary，所以从问题中找关键词不行，可以使用排除法。A的marshland做关键词定位至最后一句，提到spartina能阻止erosion和marshland deterioration，与A的decline是同义替换，正确；B的substrate elevation，C的reduce brackishness和D的increase the flow of water原文都未提及。
Question 9 of 14
解析：提问给生物带来了什么不好的影响，该段第三句话提到spartina把tidal mudflat升高，使得环境变得对那些依靠mudflat的fish和waterfowl不利，所以答案是C。A错误，原文提到trapping sediment，不是fish and waterfowl；B的transport错误，原文说的是阻止harvest；原文中把marshy fringe变成salt meadow，不是D的expand，D错误。
Question 10 of 14
解析：modify“改变”，所以正确答案是B。原文提到spartina怎么了tidal mudflats，turning into是对前文modify的解释，所以正确答案是change。A“创造”C“生长”和D“打破”完全不合文意。
Question 11 of 14
Question 12 of 14
Question 13 of 14
解析：两个过渡点，分别是名词high salinities和连词because，以high salinities做关键词可以确定答案是B或者C，但按照正常的叙述方式，先现象后原因，所以应该先说能够在高盐度环境下生存，再说原因，所以根据because确定正确答案是C。
Question 14 of 14