V2
說同一類植物對環(huán)境的差異，角色一種植物，一只動物，還有一只螞蟻。說動物吸食植物汁液，同時分泌一種物質(zhì)吸引螞蟻，螞蟻再保護這兩個東東不受其他敵人的侵害。然后做了個實驗，有32個不同的該類植物對照，發(fā)現(xiàn)20種植物發(fā)現(xiàn)了預(yù)期的現(xiàn)象，動物增加了，但其他12種植物動物反而減少了。然后解釋說這是因為不同植物的差異造成的，共生是有代價的云云。
V3
770大牛提供)跟背景資料的那篇文章還是改動比較大。但是強烈推薦讀那個補充文章。描述的試驗和原理都是一樣的。讀懂那個這篇就差不多了。
第一段好像是綜述說自然界有些有趣的關(guān)系。(很模糊，不過第一段沒有考點)
第二段描述了一下他們仨互利的機理。milkweed分泌sap給aphid吃，aphid在分泌一些東西給ant吃，然后ant就保護milkweed和aphid。科學(xué)家們證明了這種關(guān)系是mutualism的什么什么。為了證明這件事兒，科學(xué)家們設(shè)計了這個試驗，把320個milkweed分成genetic distinct的32組，開始研究。
第三段講了實驗結(jié)果。其中有20組，as expected，是aphid多了，ant也多了，increase了百分之好幾百。另外12組呢，非常令人意外的是，aphid和ant反而少了。(這里有考題)
第四段就兩句話。第一句話解釋了一下，他們仨怎么合作的，就是ant去打milkweed的一些天敵如caterpillar，as shown by another study(這里有考題，問提到另一個study的作用)。然后說，但是milkweed這樣喂aphid也是有代價的(at some cost)：他們的water和sugar都會損失掉。所以，對有些比較強壯的milkweed來說，it's an advantage to have fewer aphid。
考題：
1。what can be inferred about milkweed?
答案：他們的sap含有sugar。比較確認。
有一個稍微混淆一點的答案是提到了fewer aphid和disadvantage的關(guān)系，我覺得說反了。還有一個是they have 32 different species，可我覺得文章里是說，32 genetic distinc group，跟32 species含義不一樣。
2。提出最后一段的another study的目的。
我選的：解釋上一段里提到的study的結(jié)果。
3。在做那個primary的實驗之前(就是32x10的那個)科學(xué)家們沒有想到的是
我選的：some milkweed have a different effect on ant-aphid relationship。
這道題就注意去看第三段，20組的那個結(jié)果的一些說法(as expected)和12組的說法，大概就知道了。
背景材料:
Who’s the boss? Milkweed is the boss.
Milkweed plants engage in a helpful bit of mutualism with the aphids and ants who take up residence on them. Aphids feed on the milkweed’s sap, then secrete honeydew, which ants eat. The ants, in turn, are the muscle of the operation—they help both the plants and the aphids by fighting off potential predators like caterpillars. The partnership goes three ways, but the power is not equal—milkweed is in control.
Researchers Kailen Mooney and Anurag Agrawal recently found that the milkweed can manipulate the relationship between ants and aphids, altering the dynamics for its own good. The scientists planted 32 groups of milkweed, with each group containing 10 siblings from the same family, in a field full of ants. In 20 of the 32 milkweed groups, the presence of ants was a big boon for aphids—the aphid population increased by 150 percent compared to plants with no ants to protect them. But in the other 12 groups, the numbers of aphids actually decreased by more than half when ants were around.
So why should the three-way arrangement benefit all parties in most cases, but not in others? Since the researchers divided milkweed into groups according to genetic families, they say the plants’ genetics must be controlling the relationship. Mooney and Agrawal aren’t exactly sure how, but they speculate that the composition of milkweed sap can vary from family to family. Perhaps some families of milkweed just didn’t need as much protection, and therefore allowed fewer aphids to live on them by producing a less inviting sap. After all, this arrangement is not free for the plants—they give up lots of sugar and water for the aphids to live on the plant and induce the ants to come.
However it happens, the scientists say, finding that plants can manipulate the ant-aphid relationship helps to explain why the numbers of aphids and ants can vary so much between one plant and another, a problem that had puzzled biologists before. Now they know—milkweed is making a power grab.
這些蚜蟲將螞蟻當(dāng)作朋友還是敵人，完全取決于它們所吃的乳草。
說同一類植物對環(huán)境的差異，角色一種植物，一只動物，還有一只螞蟻。說動物吸食植物汁液，同時分泌一種物質(zhì)吸引螞蟻，螞蟻再保護這兩個東東不受其他敵人的侵害。然后做了個實驗，有32個不同的該類植物對照，發(fā)現(xiàn)20種植物發(fā)現(xiàn)了預(yù)期的現(xiàn)象，動物增加了，但其他12種植物動物反而減少了。然后解釋說這是因為不同植物的差異造成的，共生是有代價的云云。
V3
770大牛提供)跟背景資料的那篇文章還是改動比較大。但是強烈推薦讀那個補充文章。描述的試驗和原理都是一樣的。讀懂那個這篇就差不多了。
第一段好像是綜述說自然界有些有趣的關(guān)系。(很模糊，不過第一段沒有考點)
第二段描述了一下他們仨互利的機理。milkweed分泌sap給aphid吃，aphid在分泌一些東西給ant吃，然后ant就保護milkweed和aphid。科學(xué)家們證明了這種關(guān)系是mutualism的什么什么。為了證明這件事兒，科學(xué)家們設(shè)計了這個試驗，把320個milkweed分成genetic distinct的32組，開始研究。
第三段講了實驗結(jié)果。其中有20組，as expected，是aphid多了，ant也多了，increase了百分之好幾百。另外12組呢，非常令人意外的是，aphid和ant反而少了。(這里有考題)
第四段就兩句話。第一句話解釋了一下，他們仨怎么合作的，就是ant去打milkweed的一些天敵如caterpillar，as shown by another study(這里有考題，問提到另一個study的作用)。然后說，但是milkweed這樣喂aphid也是有代價的(at some cost)：他們的water和sugar都會損失掉。所以，對有些比較強壯的milkweed來說，it's an advantage to have fewer aphid。
考題：
1。what can be inferred about milkweed?
答案：他們的sap含有sugar。比較確認。
有一個稍微混淆一點的答案是提到了fewer aphid和disadvantage的關(guān)系，我覺得說反了。還有一個是they have 32 different species，可我覺得文章里是說，32 genetic distinc group，跟32 species含義不一樣。
2。提出最后一段的another study的目的。
我選的：解釋上一段里提到的study的結(jié)果。
3。在做那個primary的實驗之前(就是32x10的那個)科學(xué)家們沒有想到的是
我選的：some milkweed have a different effect on ant-aphid relationship。
這道題就注意去看第三段，20組的那個結(jié)果的一些說法(as expected)和12組的說法，大概就知道了。
背景材料:
Who’s the boss? Milkweed is the boss.
Milkweed plants engage in a helpful bit of mutualism with the aphids and ants who take up residence on them. Aphids feed on the milkweed’s sap, then secrete honeydew, which ants eat. The ants, in turn, are the muscle of the operation—they help both the plants and the aphids by fighting off potential predators like caterpillars. The partnership goes three ways, but the power is not equal—milkweed is in control.
Researchers Kailen Mooney and Anurag Agrawal recently found that the milkweed can manipulate the relationship between ants and aphids, altering the dynamics for its own good. The scientists planted 32 groups of milkweed, with each group containing 10 siblings from the same family, in a field full of ants. In 20 of the 32 milkweed groups, the presence of ants was a big boon for aphids—the aphid population increased by 150 percent compared to plants with no ants to protect them. But in the other 12 groups, the numbers of aphids actually decreased by more than half when ants were around.
So why should the three-way arrangement benefit all parties in most cases, but not in others? Since the researchers divided milkweed into groups according to genetic families, they say the plants’ genetics must be controlling the relationship. Mooney and Agrawal aren’t exactly sure how, but they speculate that the composition of milkweed sap can vary from family to family. Perhaps some families of milkweed just didn’t need as much protection, and therefore allowed fewer aphids to live on them by producing a less inviting sap. After all, this arrangement is not free for the plants—they give up lots of sugar and water for the aphids to live on the plant and induce the ants to come.
However it happens, the scientists say, finding that plants can manipulate the ant-aphid relationship helps to explain why the numbers of aphids and ants can vary so much between one plant and another, a problem that had puzzled biologists before. Now they know—milkweed is making a power grab.
這些蚜蟲將螞蟻當(dāng)作朋友還是敵人，完全取決于它們所吃的乳草。