Version 3:一个说的是dodder, 第一段说的它是一定要在一个星期内找到寄主，不然会死。又说一般它的寄主最后都会死(有题，那个must be true,里面有个选项，dodder will eventually kill the plant)。它还引起了某年西红柿的收成损失xxx(一个数目或者比例)。第二段说作相关的研究，开始种在一片地方，放其他植物在旁边，它不会倍吸引过去。然后放放西红柿就倍吸引过去了。然后研究人员在西红柿研究出了7种香素，这些香素有几种在wheat中也有，但是wheat中还有一种抑制dodder的香素。最后一段我忘了说什么了。有一道题目是问第二段中说了些什么。选项中有个选项是出现在第一段的，一个说dodder需要在一个星期内找到寄主，不然会死去。正确的选项应该是wheat中有一种抑制dodder的香素。
At first, the researchers set various possible targets several centimeters from dodder sprouts. A pot of moist soil alone didn't attract the seedlings, nor did vials of dyed water that created colored light. But a pot with a young tomato plant, and even a cup of perfume made of tomato volatiles, did attract the seedlings
我記得最後一句是..... dodder grows toward impatiens and tomatoes, but not wheat.
Q:問整個第三段的功能(整個第三段反黃):有兩個選項很像A:針對前面講到的題出一個conclusion 另一個:.....findings 我好像選這個這題很不確定大家要在判斷一下
第三段:整段就在解釋為什麼wheat不會attract dodder,科學家分析tomato中有7種perfume其中有四種會吸引dodder,wheat也有其中一種,但是wheat也有一種東西會repel dodder,因此提供了一種可以防治dodder的想法
When researchers tested seven ingredients in the tomato perfume individually, three of them proved attractive to the dodder. One of those attractants showed up in wheat, but the wheat perfume also contained a substance that repelled the seedlings. Such a repellent might offer a new route for fighting dodder
Scent Stalking: Parasitic vine grows toward tomato odor
A wiry orange vine finds plants to raid for nutrients by growing toward their smell, researchers report.
One of the parasitic plants called dodders responds to volatile compounds wafting off nearby plants and shows preferences for certain species, says Consuelo De Moraes of Pennsylvania State University in University Park. They say that their new work marks the first time that anyone has shown that a plant will grow toward airborne chemicals from other plants.
The experiment finally identifies a cue—scent—that draws dodder to its victims, adds Mark C. Mescher, also of Penn State
The U.S. Department of Agriculture lists dodder among the country's 10 worst weeds. When a dodder seed sprouts, it doesn't grow roots. All its energy goes into a tendril that shoots out in search of plants to tap for water and nutrients. If it's going to survive, it must latch on to a victim within about a week. The vine grows into a spaghetti tangle and can attack multiple plants, stunting their growth but not killing them.
Of the 150 species of dodder, the researchers selected Cuscuta pentagona, says coauthor Justin Runyon, also of Penn State. This species bedevils tomato growers in California, where it costs them an estimated $4 million a year in reduced yields.
De Moraes' team and other researchers have studied the volatile compounds released by plants that are mauled by caterpillars or other pests. In the new study, reported in the Sept. 29 Science, the team took a different point of view, looking at how an attacker, the dodder, takes advantage of volatiles to target its prey.
At first, the researchers set various possible targets several centimeters from dodder sprouts. A pot of moist soil alone didn't attract the seedlings, nor did vials of dyed water that created colored light.But a pot with a young tomato plant, and even a cup of perfume made of tomato volatiles, did attract the seedlings
To minimize any confounding cues, such as shading or light, the researchers then set the possible attractants in chambers connected to the plant by curving pipes. Again, the seedlings grew toward the scent.
Testing various victim species, the researchers found that dodder grows toward impatiens and tomatoes.Wheat won't sustain dodder well, and given a choice, parasite seedlings shunned it and grew toward tomatoes.
When researchers tested seven ingredients in the tomato perfume individually, three of them proved attractive to the dodder. One of those attractants showed up in wheat, but the wheat perfume also contained a substance that repelled the seedlings. Such a repellent might offer a new route for fighting dodder, Mescher speculates.
An insect ecologist who has also studied plant volatiles, Rick Karban of the University of California, Davis comments, "The significance of this [study] to me is that it indicates that without a central nervous system, plants are capable of behaving in ways that appear fairly sophisticated."
Massachusetts Institute of Technology GRE: 1353 GMAT:720 Stanford University (CA) GRE: 1354 GMAT:720 University of California–Berkeley GRE: 1353 GMAT:707 Georgia In
GMAT考试是美国管理专业招收研究生委员会主办和负责指导的考试, 其英文全称是Graduate Management Admission Test。GMAT考试的科目包括会计学、经济学、管理学、普通管理、生产管理、行政管理、