什么是藻类
一群主要是水生的、能行光合作用而无法精确定义的有机体。大小不一,从显微镜下的单细胞鞭毛虫,到长达60公尺的大型褐藻。藻类提供了地球上大部分的氧气,是几乎所有的水生生物的食物基地,并提供食品和工业产品,包括石油产品。它们的光合作用色素比植物的更为多样,它们的细胞中具有植物和动物所没有的特点。随着新的分类法资讯的发现,藻类的分类也在迅速改变。以前,藻类按它们叶绿体里的色素分子分成红藻、褐藻与绿藻三类。现在辨认出的种类远远多於这三类,每一种都有共同的色素类型。从演化的意义上看,藻类彼此间的关系并不密切。某些种群与原生动物和真菌的区别只在於它们有叶绿体以及能行光合作用的能力,因此从演化上来看,它们与原生动物或真菌的关系比与其他藻类的关系更为接近。利用藻类的历史或许与人类的历史一样悠久,沿海的居民食用海藻,许多餐馆里都提供藻类食品。它们常见於溪流中「黏滑的」岩石上(参阅diatom),是池塘上绿色光辉之源。
algae
Any of a group of mostly aquatic, photosynthetic organisms (see photosynthesis) that defy precise definition. They range in size from the microscopic flagellate Micromonas to giant kelp that reach 200 ft (60 m) in length. Algae provide much of the earth's oxygen, serve as the food base for almost all aquatic life, and provide foods and industrial products, including petroleum products. Their photosynthetic pigments are more varied than those of plants, and their cells have features not found among plants and animals. The classification of algae is changing rapidly as new taxonomical information is discovered. Algae were formerly classified into three major groups—the red, brown, and green seaweeds—based on the pigment molecules in their chloroplasts. Many more than three groups are now recognized, each sharing a common set of pigment types. Algae are not closely related to each other in an evolutionary sense. Specific groups can be distinguished from protozoans and fungi (see fungus) only by the presence of chloroplasts and their ability to carry out photosynthesis, and thus have a closer evolutionary relationship with the protozoa or fungi than with other algae. Use of algae is perhaps as old as mankind; seaweeds are eaten by coastal societies, and algae are served in many restaurants. They are common on “slimy” rocks in streams (see diatoms) and as green sheens on pools and ponds.
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隋侯之珠是什么意思?
意思是:隋:古国名。比喻珍贵的物品。成语名字:隋侯之珠成语发音:suíhóuzhīzhū成语解释:隋:古国名。比喻珍贵的物品。成语出处:《庄子让王》:“今且有人于此,以隋侯之珠,弹千仞之雀,世必笑之。是何也?则其所用者重,而所要者轻也。《淮南子览冥训》:“譬如隋侯之珠,和氏之璧...
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运筹借箸是什么意思?
意思是:同“运箸”。成语名字:运筹借箸成语发音:yùnchóujièzhù成语解释:同“运箸”。成语出处:《史记·留侯世家》:“汉王方食,曰:‘子房前!客有为我计桡楚权者。’具以丽生语告,曰:‘于子房何如?’……张良对曰:‘臣请藉前箸为大王筹之!’”裴骃集解引张晏曰:“求借所食...
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鲁卫之政是什么意思?
意思是:语出《论语·子路》:“鲁卫之政,兄弟也。”鲁是周朝周公的封国,卫是周公之弟康叔的封国,两国的政治情况也像兄弟一样差不多。因以比喻情况相同或相似。成语名字:鲁卫之政成语发音:lǔwèizhīzhèng成语解释:语出《论语·子路》:“鲁卫之政,兄弟也。”鲁是周朝周...
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以肉啖虎是什么意思?
意思是:见“以肉餧虎”。成语名字:以肉啖虎成语发音:yǐròudànhǔ成语解释:见“以肉餧虎”。成语出处:明·李贽《史纲评要·周纪·赧王》:“以揽权要秦王,正如以肉啖虎耳。”成语繁体:以肉啗虎感情色彩:中性成语成语用法:作宾语、定语;用于比喻句成语结构:偏正式成语产生...