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Larvae of many marine invertebrate species delay their metamorphosis into juveniles when cues signaling an appropriate juvenile environment are absent, thereby increasing their likelihood of thriving as juveniles and of ultimately reaching adulthood. Nevertheless, delayed metamorphosis has potential costs for juveniles, including reduced growth and increased mortality. Nearly all evidence of such costs involves species whose larvae do not feed but rather subsist on stored nutrients, indicating that insufficient energy reserves may be an underlying cause of these costs. Supporting this hypothesis are laboratory studies showing that in a certain bryozoan, the prolonged larval swimming that results from delayed metamorphosis is associated with size reductions in the juvenile feeding organ (the lophophore) and that one factor influencing the size of juveniles of certain barnacle species is how long larvae delay metamorphosis. However, other studies show that while significantly fewer juvenile Capitella worms survived to adulthood when metamorphosis had been delayed, prolonged larval swimming had no significant effect on juvenile size, suggesting, perhaps, that in some species, factors other than insufficient energy reserves account for the negative effects of the larval stresses that result from delayed metamorphosis.
1. The passage suggests that the “bryozoan,” the “barnacle species,” and “Capitella worms” all share which of the following characteristics?
A. The larvae of these species do not feed but rather subsist on stored nutrients.
B. The larvae of these species are unable to undergo metamorphosis if larval swimming is significantly prolonged.
C. The larvae of these species do not have enough energy to meet their needs when metamorphosis is delayed.
D. The juveniles of these species manifest the negative effects of delayed metamorphosis as a decrease in size.
E. The juveniles of these species are not significantly larger than their respective larvae.
推斷題
解析：文章里面討論的所有蟲(chóng)都是會(huì)靠之前儲(chǔ)存的能量維持生活，而且對(duì)應(yīng)到文章這一句話“Nearly all evidence of such costs involves species whose larvae do not feed but rather subsist on stored nutrients, indicating that insufficient energy reserves may be an underlying cause of these costs.” B選項(xiàng)無(wú)中生有。C選項(xiàng)也是無(wú)中生有。D選項(xiàng)不是一定會(huì)減少尺寸，however后面有轉(zhuǎn)折。E選項(xiàng)也是無(wú)中生有。
2. The “hypothesis” implies that compared to marine invertebrate larvae that subsist on stored nutrients, marine invertebrate larvae that feed are less likely to
A. exhibit prolonged larval swimming as a result of delayed metamorphosis.
B. experience negative effects as a result of delayed metamorphosis.
C. thrive as juveniles in environments inappropriate for juveniles.
D. delay metamorphosis in the absence of appropriate environmental cues.
E. delay metamorphosis for an extended period of time.
解析：假設(shè)的內(nèi)容是，Nearly all evidence of such costs involves species whose larvae do not feed but rather subsist on stored nutrients, indicating that insufficient energy reserves may be an underlying cause of these costs. 所以如果feed的幼蟲(chóng)就更不太可能遇到這種負(fù)面的結(jié)果。所以答案選B。
3. The passage is primarily concerned with
A. weighing the relative benefits and costs of delayed metamorphosis.
B. illustrating the range of costs that can result from delayed metamorphosis.
C. speculating on why the costs of delayed metamorphosis have gone unrecognized.
D. discussing a possible explanation of the costs of delayed metamorphosis.
E. debunking the notion that the costs of delayed metamorphosis are negligible.
文章目的題
解析：這篇文章都是在解釋delayed metamorphosis costs的原因，就是想告訴我們?yōu)槭裁磀elayed metamorphosis會(huì)產(chǎn)生哪些不好的costs，所以答案選D。
