郴州包皮龟头炎治疗
时间:2020年01月27日 06:31:51

Plants attract fruit eaters,or ;frugivores;ndash;by packing valuable resources into their fruits like sugar and water or important nutrients such as carotenoids, vitamins and minerals. Plants often target specific animals that will give their seeds the best chances for germination, and discourage or repel animals that wonrsquo;t. Plants that want to attract birds rather than mammals might produce thorns or have fruits that taste unpalatable to most mammals but tasty to birds. Plants that want to repel birds but attract mammals might have fruits with thicker, tougher outer skins. Donrsquo;t forget that selective breeding by humans has dramatically changed many fruits from their wild state, often resulting in larger, sweeter fruits with fewer seeds.通过为吃果实的动物提供富含营养的果实,比如:糖,水或类胡萝卜素,维他命和矿物质等重要成分,植物来吸引吃果实的动物。植物往往以特定的动物为特定目标,那些动物会使植物种子有发芽的最佳机会,反之,则会阻止或击退其他对种子发芽不利的动物。要吸引鸟类而不是吸引哺乳动物的植物,可能会带刺或结出对多数哺乳类动物难吃,但对鸟类美味的果实。想吸引哺乳动物的植物而不是鸟类的植物,结出的水果可能有更厚,更粗糙的外皮。不要忘了人类选择性育种已戏剧性地改变了许多水果,将植物的野生状态改变成果实较大,口味更甜,籽更少的果实。201201/168938

Life Traces in Lava熔岩中的生命足迹Don: Can I ask you something, Yaeuml;l?Y 我能问你一个事情吗?Yaeuml;l: Sure!当然!D: Do you ever stop to think about how all living things are ultimately related?你有没有停下来想过人类最初是怎么来的呢?Y: Eh…Yeah, sure.额…当然啦!D: Bu...but Im serious. Doesnt it amaze you to realize that we can trace life back millions and millions of years ago to single-celled organisms floating around in the ocean?我认真的!当你意识到人类的起源可以追溯到数百万年前漂浮在海洋里的单细胞生物时,难道你一点也不惊叹于造物的神奇?Y: Millions? Actually, its billions and billions.数百万?实际上,应该是“数十亿”吧!D: Billions?十亿?Y: Yes, billion! Scientists have discovered lava rock taken from the ocean floor that contains remnants of life that are billions of years old. Three point five billion years, to be precise.恩,十亿。科学家在海洋底部发现了含有数十亿年前的生物残余的熔岩。准确的说,是35亿年前。D: What do they find, fossils?他们发现的是什么?化石?Y: Sort of. At certain spots the ocean floor oozeslava, which cools and forms rock formations. Microorganisms set up shop on the surface of these rocks and thrive on their rich chemical content. The microbes leave traces of their presence in the rocks in the form of tiny tubes.好像是。海底的某些地方会渗出岩浆,冷却过后便形成了岩石。微生物便在这些岩石表面“安营扎寨”,靠着岩石中丰富的化学成分生长繁衍。这些微生物在岩石中呈微型管状,留下了他们存在的“足迹”。When researchers looked at three billion plus year old rocks and saw these kinds of tubes, they suspected that microbes once inhabited them. The most convincing piece of evidence was a type of carbon found in the tubes thats produced by living things. So far, this is one of the oldest traces of life ever found.当研究人员对这些经历了30多亿年“磨炼”的岩石进行研究时,发现了这些微型的小管,便设想微生物曾经栖居于这些岩石之上。最有力的据是科学家在这些管状物中发现了一种碳,而这种碳物质仅由生物产生。这是迄今为止发现的最早的生命的“足迹”。 /201208/195981


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