生物類話題是托福閱讀中最常見話題之一，當(dāng)然對于生物的考察也不僅僅局限于陸地，還會延伸至海洋，說到海洋生物，大家對珊瑚(coral)一定并不陌生，但是珊瑚礁(coral reef)是如何形成、又如何分類呢?今天我們就一起來看一看托福閱讀生物類背景知識及真題。

托福閱讀生物類背景知識

珊瑚礁

珊瑚礁(coral reef)是指造礁石珊瑚群體死后其遺骸(remains)構(gòu)成的巖體。珊瑚礁的主體是由珊瑚蟲(polyp)組成的。珊瑚蟲是海洋中的一種腔腸動物在生長過程中能吸收海水中的鈣和二氧化碳，然后分泌出石灰石(limestone)，變?yōu)樽约荷娴耐鈿?。每一個單體的珊瑚蟲只有米粒那樣大小，它們一群一群地聚居在一起，一代代地新陳代謝(metabolism)，生長繁衍，同時不斷分泌出石灰石，并粘合在一起。這些石灰石經(jīng)過以后的壓實(shí)、石化，形成島嶼和礁石，也就是所謂的珊瑚礁(coral reef)。

達(dá)爾文根據(jù)礁體與岸線的關(guān)系，劃分出岸礁(fringing reef)、堡礁(barrier reef)和環(huán)礁(atoll)。

fringing reef

暗礁

沿大陸(mainland)或島嶼(island)岸邊(shore)生長發(fā)育，亦稱裙礁或邊緣礁?，F(xiàn)代最長的岸礁沿紅海沿岸發(fā)育，綿延約2700多公里，分布水深約36米。中國臺灣恒春半島和海南島沿岸也有岸礁發(fā)育。

barrier reef

堡礁

又稱堤礁，是離岸有一定距離的堤狀礁體，它與陸地隔以瀉湖(環(huán)礁湖)(lagoon)?，F(xiàn)代規(guī)模最大的堡礁是澳大利亞昆士蘭大堡礁，全長約2000公里，分布水深約30米。

atoll

環(huán)礁

礁體呈環(huán)帶狀圍繞瀉湖(lagoon)，有的與外海有水道相通。環(huán)礁直徑在幾百米至幾十公里，形態(tài)多樣。已知的環(huán)礁有330個之多,主要分布在西太平洋的信風(fēng)帶和印度洋熱帶海域。環(huán)礁多坐落在大洋火山錐上，孤立于汪洋大海之中，展布受洋底火山(volcano)作用的控制，某些也可在大陸架(continental shelf)上見到。環(huán)礁礁坪上常有灰砂(礫)島或礁巖島，統(tǒng)稱為珊瑚島。

馬紹爾群島上的夸賈林環(huán)礁和馬爾代夫群島的蘇瓦迪瓦環(huán)礁，面積都在1800平方公里以上，是世界上最大的兩個環(huán)礁。南海發(fā)育的環(huán)礁頗具特色，有瀉湖全被封閉的玉琢礁;有瀉湖與外海有3個通道的華光礁;還有多通道開放式的永樂環(huán)礁，半月形全開放式的宣德環(huán)礁。永樂環(huán)礁和宣德環(huán)礁均發(fā)育有灰砂島和礁巖島，其中最大的灰砂島是永興島，面積1.85平方公里。

托福閱讀真題練習(xí)：蝴蝶

托福閱讀文本：

Butterflies are among the most extensively studied insects — it is estimated that 90 percent of the world's species have scientific names. As a consequence, they are perhaps the best group of insects for examining patterns of terrestrial biotic diversity and distribution. Butterflies also have a favorable image with the general public. Hence, they are an excellent group for communicating information on science and conservation issues such as diversity.

Perhaps the aspect of butterfly diversity that has received the most attention over the past century is the striking difference in species richness between tropical and temperate regions. For example, in 1875 one biologist pointed out the diversity of butterflies in the Amazon when he mentioned that about 700 species were found within an hour's walk, whereas the total number found on the British islands did not exceed 66, and the whole of Europe supported only 321. This early comparison of tropical and temperate butterfly richness has been well confirmed.

A general theory of diversity would have to predict not only this difference between temperate and tropical zones, but also patterns within each region, and how these patterns vary among different animal and plant groups. However, for butterflies, variation of species richness within temperate or tropical regions, rather man between them, is poorly understood. Indeed, comparisons of numbers of species among the Amazon basin, tropical Asia, and Africa are still mostly "personal communication" citations, even for vertebrates. In other words, unlike comparison between temperate and tropical areas, these patterns are still in the documentation phase.

In documenting geographical variation in butterfly diversity, some arbitrary, practical decisions are made. Diversity, number of species, and species richness are used synonymously;little is known about the evenness of butterfly distribution. The New World butterflies make up the preponderance of examples because they are the most familiar species. It is hoped that by focusing on them, the errors generated by imperfect and incomplete taxonomy will be minimized.

托福閱讀題目：

1. Which aspect of butterflies does the passage mainly discuss?

(A) Their physical characteristics

(B) Their names

(C) Their adaptation to different habitats

(D) Their variety

2. The word "consequence" in line 2 is closest in meaning to

(A) result

(B) explanation

(C) analysis

(D) requirement

3. Butterflies are a good example for communicating information about conservation issues

because they

(A) are simple in structure

(B) are viewed positively by people

(C) have been given scientific names

(D) are found mainly in temperate climates

4. The word "striking" in line 8 is closest in meaning to

(A) physical

(B) confusing

(C) noticeable

(D) successful

5. The word "exceed" in line 11 is closest in meaning to

(A) locate

(B) allow

(C) go beyond

(D) come close to

6. All of the following are mentioned as being important parts of a general theory of diversity EXCEPT

(A) differences between temperate and tropical zones

(B) patterns of distribution of species in each region

(C) migration among temperate and tropical zones

(D) variation of patterns of distribution of species among different animals and plants

7. The author mentions tropicalAsia in lines 19 as an example of a location where

(A) butterfly behavior varies with climate

(B) a general theory of butterfly diversity has not yet been firmly established

(C) butterflies are affected by human populations

(D) documenting plant species is more difficult than documenting butterfly species

8. Which of the following is NOT well understood by biologists?

(A) European butterfly habitats

(B) Differences in species richness between temperate and tropical regions

(C) Differences in species richness within a temperate or a tropical region

(D) Comparisons of behavior patterns of butterflies and certain animal groups

9. The word "generated" in line 26 is closest in meaning to

(A) requested

(B) caused

(C) assisted

(D) estimated

托福閱讀答案：

DABCC CBCB

托福閱讀真題練習(xí)：海洋文化

托福閱讀文本：

The Native American peoples of the north Pacific Coast created a highly complex maritime culture as they invented modes of production unique to their special environment. In addition to their sophisticated technical culture, they also attained one of the most complex social organizations of any nonagricultural people in the world.

In a division of labor similar to that of the hunting peoples in the interior and among foraging peoples throughout the world, the men did most of the fishing, and the women processed the catch.

Women also specialized in the gathering of the abundant shellfish that lived closer to shore. They collected oysters, crabs, sea urchins, mussels, abalone, and clams, which they could gather while remaining close to their children. The maritime life harvested by the women not only provided food, but also supplied more of the raw materials for making tools than did fish gathered by the men. Of particular importance for the native tool kit before the introduction of metal was the wide knife made from the larger mussel shells, and a variety of cutting edges that could be made from other marine shells.

The women used their tools to process all of the fish and marine mammals brought in by the men. They cleaned the fish, and dried vast quantities of them for the winter. They sun-dried fish when practical, but in the rainy climate of the coastal area they also used smokehouses to preserve tons of fish and other seafood annually. Each product had its own peculiar characteristics that demanded a particular way of cutting or drying the meat, and each task required its own cutting blades and other utensils.

After drying the fish, the women pounded some of them into fish meal, which was an easily transported food used in soups, stews, or other dishes to provide protein and thickening in the absence of fresh fish or while on long trips. The woman also made a cheese-like substance from a mixture of fish and roe by aging it in storehouses or by burying it in wooden boxes or pits lined with rocks and tree leaves.

托福閱讀題目：

1. Which aspect of the lives of the Native Americans of the north Pacific Coast does the passage

mainly discuss?

(A) Methods of food preservation

(B) How diet was restricted by the environment

(C) The contributions of women to the food supply

(D) Difficulties in establishing successful farms

2. The word "unique" in line 2 is closest in meaning to

(A) comprehensible

(B) productive

(C) intentional

(D) particular

3. The word "attained" in line 3 is closest in meaning to

(A) achieved

(B) modified

(C) demanded

(D) spread

4. It can be inferred from paragraph 1 that the social organization of many agricultural peoples is

(A) more complex than that of hunters and foragers

(B) less efficient than that of hunters and foragers

(C) more widespread than that of hunters and foragers

(D) better documented than that of hunters and foragers

5.According to the passage , what is true of the "division of labor" mentioned in line 5?

(A) It was first developed by NativeAmericans of the north Pacific Coast.

(B) It rarely existed among hunting

(C) It was a structure that the Native Americans of the north Pacific Coast shared with many other

peoples.

(D) It provided a form of social organization that was found mainly among coastal peoples.

6. The word "abundant" in line 7 is closest in meaning to

(A) prosperous

(B) plentiful

(C) acceptable

(D) fundamental

7.All of the following are true of the north Pacific coast women EXCEPT that they

(A) were more likely to catch shellfish than other kinds of fish

(B) contributed more materials for tool making than the men did

(C) sometimes searched for food far inland from the coast

(D) prepared and preserved the fish

8. The word "They" in line 16 refers to

(A) women

(B) tools

(C) mammals

(D) men

9. The NativeAmericans of the north Pacific Coast used smokehouses in order to

(A) store utensils used in food preparation

(B) prevent fish and shellfish from spoiling

(C) have a place to store fish and shellfish

(D) prepare elaborate meals

10. The wore "peculiar" in line 19 is closest in meaning to

(A) strange

(B) distinctive

(C) appealing

(D) biological

11. All of following are true of the cheese-like substance mentioned in paragraph 4 EXCEPT that

it was

(A) made from fish

(B) not actually cheese

(C) useful on long journeys

(D) made in a short period of time

托福閱讀答案：

CDAAC BCABB D

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