GMAT阅读资料第61篇

***ral reefs are o*** of the most fragile, biolog***ally ***mplex, and diverse mar***e e***system on Earth. This e***system is o*** of the fasc***at***g paradoxes of the bio- sphere: how do clear, and thus nutrient-po***, waters sup- (5) p***t such pro***f*** and productive ***mmunities? Part of the answer ***es with*** the tissues of the ***rals themselves. Symbiot*** cells of algae known as zooxanthellae carry out pho***synthesis us***g the ***tabo***c wastes of the ***ral thereby produc***g food f*** themselves, f*** their ***rals, (10) hosts, and even f*** other ***mbers of the reef ***mmunity. This symbiot*** process allows ***ganisms *** the reef ***m- munity *** use sparse nutrient resources eff***iently.

　　Unf***tunately f*** ***ral reefs, however, a variety of human acti***ties are c***s***g w***ldwide degradation of (15) shallow mar***e habitats by add***g nutrients *** the (water. Agr***u***ure, slash-and-burn land clear***g, sewage disposal and manufactur***g that creates waste by-products all ***crease nutrient loads *** these waters. Typ***al symp***ms of reef dec****** are destabi***z*** herbiv***e populations and (20) an ***creas***g abundance of algae and fi***er-fe******g animals. Dec******s *** reef ***mmunities are ***nsistent with observa- tions that nutrient ***put is ***creas***g *** direct prop***tion *** grow***g human populations, thereby threaten***g reef ***m- (25) munities sen***ive *** subtle changes *** nutrient ***put *** their waters.

　　1. The passage is primarily ***ncer***d with

　　(A) describ***g the effects of human acti***ties on algae *** ***ral reefs

　　(B) expla******g how human acti***ties are pos***g a threat *** ***ral reef ***mmunities

　　(C) discuss***g the process by wh***h ***ral reefs deteri***ate *** nutrient-po*** waters

　　(D) expla******g how ***ral reefs produce food f*** themselves

　　(E) describ***g the abundance of algae and fi***er-fe******g animals *** ***ral reef areas

　　2. The passage suggests wh***h of the follow***g about ***ral reef ***mmunities?

　　(A) ***ral reef ***mmunities may actually be m***e ***kely *** thrive *** waters that are relatively low *** nutrients.

　　(B) The nutrients on wh***h ***ral reef ***mmunities thrive are o***y found *** shallow waters.

　　(C) Human population growth has l*** *** chang***g ocean temperatures, wh***h threatens ***ral reef ***mmunities.

　　(D) The growth of ***ral reef ***mmunities tends *** destabi***ze underwater herbiv***e populations.

　　(E) ***ral reef ***mmunities are m***e ***mplex and diverse than most e***systems locat*** on dry land.

　　3. The ***th*** refers *** "fi***er-fe******g animals" (****** 20) *** ***der ***

　　(A) pro***de an example of a characterist*** sign of reef deteri***ation

　　(B) expla*** how reef ***mmunities acquire sustenance f*** sur***val

　　(C) identify a fac***r that helps herbiv***e populations thrive

　　(D) ***d***ate a c***se of decreas***g nutrient ***put *** waters that reefs ***habit

　　(E) identify ***mbers of ***ral reef ***mmunities that rely on ***ral reefs f*** nutrients

　　4. A******d***g *** the passage, wh***h of the follow***g is a fac***r that is threaten***g the sur***val of ***ral reef ***mmunities?

　　(A) The waters they ***habit ***nta*** few nutrient resources.

　　(B) A dec****** *** nutrient ***put is disrupt***g their symbiot*** relationship with zooxanthellae

　　(C) The degrad*** waters of their mar***e habitats h**e r***uc*** their abi***ty *** carry out pho***synthesis

　　(D) They are ***o biolog***ally ***mplex *** sur***ve *** habitats with m***imal nutrient ***put.

　　(E) Waste by-products resu*** *** an ***crease *** nutrient ***put *** reef ***mmunities.

　　5. It can be ***ferr*** from the passage that the ***th*** describes ***ral reef ***mmunities as paradox***al most ***kely f*** wh***h of the follow***g reasons?

　　(A) They are thri***ng even though human acti***ties h**e deplet*** the nutrients *** their en***ron***nt.

　　(B) They are able *** sur***ve *** spite of an over- abundance of algae ***habit***g their waters.

　　(C) They are able *** sur***ve *** an en***ron***nt with ***mit*** food resources.

　　(D) Their ***tabo***c wastes ***ntribute *** the degra- dation of the waters that they ***habit.

　　(E) They are dec***n***g even when the water sur- round***g them rema***s clear.