首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
"Producers, Consumers, and Decomposers" P1 Organisms that are capable of using carbon dioxide as their sole source of carbon
"Producers, Consumers, and Decomposers" P1 Organisms that are capable of using carbon dioxide as their sole source of carbon
admin
2018-06-21
64
问题
"Producers, Consumers, and Decomposers"
P1 Organisms that are capable of using carbon dioxide as their sole source of carbon are called autotrophs (self-feeders), or producers. These are the plants. They chemically fix carbon through photosynthesis. Organisms that depend on producers as their carbon source are called heterotrophs (feed on others), or consumers. Generally, these are animals. From the producers, which manufacture their own food, energy flows through the system along a circuit called the food chain, reaching consumers and eventually detritivores. Organisms that share the same basic foods are said to be at the same trophic level. Ecosystems generally are structured in a food web, a complex network of interconnected food chains. In a food web, consumers participate in several different food chains, comprising both strong interactions and weak interactions between species in the food web.
P2 Primary consumers feed on producers. A Because producers are always plants, the primary consumer is called an herbivore, or plant eater. A carnivore is a secondary consumer and primarily eats meat. B A consumer that feeds on both producers (plants) and consumers (meat) is called an omnivore. C
P3 Detritivores (detritus feeders and decomposers) are the final link in the endless chain. D Detritivores renew the entire system by releasing simple inorganic compounds and nutrients with the breaking down of organic materials. Detritus refers to all the dead organic debris—remains, fallen leaves, and wastes—that living processes leave. Detritus feeders—worms, mites, termites, centipedes, snails, crabs, and even vultures, among others—work like an army to consume detritus and excrete nutrients that fuel an ecosystem. Decomposers are primarily bacteria and fungi that digest organic debris outside their bodies and absorb and release nutrients in the process. This metabolic work of microbial decomposers produces the rotting that breaks down detritus. Detritus feeders and decomposers, although different in operation, have a similar function in an ecosystem.
P4 An example of a complex community is the oceanic food web that includes krill, a primary consumer. Krill is a shrimplike crustacean that is a major food for an interrelated group of organisms, including whales, fish, seabirds, seals, and squid in the Antarctic region. All of these organisms participate in numerous other food chains as well, some consuming and some being consumed.
Phytoplankton
begin this chain by harvesting solar energy in photosynthesis. Herbivorous zoo-plankton such as krill and other organisms eat Phytoplankton. Consumers eat krill at the next
trophic level
. Because krill are a protein-rich, plentiful food, increasingly factory ships, such as those from Japan and Russia, seek them out. The annual krill harvest currently surpasses a million tons, principally as feed for chickens and livestock and as protein for human consumption.
Efficiency in a Food Web
P5 Any assessment of world food resources depends on the level of consumer being targeted. Let us use humans as an example. Many people can be fed if wheat is eaten directly. However, if the grain is first fed to cattle (herbivores) and then we eat the beef, the yield of available food energy is cut by 90% (810 kg of grain is reduced to 82 kg of meat); far fewer people can be fed from the same land area.
P6 In terms of energy, only about 10% of the kilocalories (food calories, not heat calories) in plant matter survive from the primary to the secondary trophic level. When humans consume meat instead of grain, there is a further loss of biomass and added inefficiency. More energy is lost to the environment at each progressive step in the food chain. You can see that an omnivorous diet such as that of an average North American and European is quite expensive in terms of biomass and energy.
P7 Food web concepts are becoming politicized as world food issues grow more critical. Today, approximately half of the cultivated acreage in the United States and Canada is planted for animal consumption—beef and dairy cattle, hogs, chickens, and turkeys. Livestock feed includes approximately 80% of the annual corn and nonexported soybean harvest. In addition, some lands cleared of rain forest in Central and South America were converted to pasture to produce beef for export to restaurants, stores, and fast-food outlets in developed countries. Thus, lifestyle decisions and dietary patterns in North America and Europe are perpetuating inefficient food webs, not to mention the destruction of valuable resources, both here and overseas.
Glossary
phytoplankton: a plant that lives in the sea and produces its own energy source
trophic level: category measured in steps away from the energy input in an ecosystem
According to the passage, all of the following characteristics describe producers EXCEPT
选项
A、Producers serve as food for consumers.
B、Producers make their own food.
C、Producers form the first trophic level.
D、Producers include bacteria and fungi.
答案
D
解析
转载请注明原文地址:https://kaotiyun.com/show/IxfO777K
0
托福(TOEFL)
相关试题推荐
ChooseTWOletters,A-E.InwhichTWOareasdidtheseresearchfindingsdifferfromthoseoftheoriginalstudy?AStudents’int
Completethenotesbelow.WriteONEWORDONLYforeachanswer.TheTawnyOwlMost【L31】______owlspeciesinUKStronglynocturna
ChooseTWOletters,A-E.WhichTWOcharacteristicsapplytothebamboooven?AIt’ssuitableforwindyweather.BThefireisli
Completetheformbelow.WriteNOMORETHANTHREEWORDSAND/ORANUMBERforeachanswer.BOOKINGINFORMATIONRoomtype【L4】_____
Completetheformbelow.WriteNOMORETHANTHREEWORDSAND/ORANUMBERforeachanswer.CUSTOMER’SINFORMATIONDETAILSName:【L
Choosethecorrectanswer,A,BorC.Whichisnotprovidedforstudentsinmostofthelargebuildings?
Completetheformbelow.WriteONEWORDONLYforeachanswer.HOUSESERVICEINFORMATIONExampleAnswerNameBarbaraHill
Completethenotesbelow.WriteNOMORETHANTWOWORDSforeachanswer.CLIMATEANDARCHITECTURECasesandexamplesarefrom
Completethenotesbelow.WriteONEWORDONLYforeachanswer.ChimpanzeeBehavioursSpeciesWecanfindPanorPanTroglody
Completethenotesbelow.WriteONEWORDONLYforeachanswer.ChimpanzeeBehavioursSpeciesWecanfindPanorPanTroglody
随机试题
患者初次门诊下列哪项措施尤为重要患者病情进一步发展,出现持续性疼痛,夜间尤为剧烈,下肢肌肉萎缩,足背动脉搏动消失,诊断为血栓闭塞性脉管炎营养障碍期。此患者与下肢动脉硬化性闭塞患者鉴别诊断的主要依据是
下列哪项不是肩关节正位影像的标准显示结构
A.麻醉药品B.一类精神药品C.二类精神药品D.医疗用毒性药品E.放射性药品生产记录应保存5年备查的药品是
筛检的目的是()
在涉外刑事诉讼中,关于国籍的确认,下列哪些做法是正确的?()
给水泵站水泵的选择应符合节能的要求,当供水量和水压变化较大时,宜选用叶片角度可调节的水泵、机组调速或()等措施。
支票可以分为( )。
甲公司是一家不锈钢生产企业,为了提高企业竞争力,甲公司决定采用平衡计分卡衡量公司绩效,并选用销售增长率、预期利润、交货时间、顾客满意度作为衡量指标,该公司选用的衡量指标涵盖的角度不包括()。
假定某日,人民币兑美元的汇率从1美元兑人民币6.91元变成1美元兑人民币6.92元,则该标价及其升贬值情况是:
阅读以下应用程序说明和C程序,将C程序段中(1)~(7)空缺处的语句填写完整。【说明】以下【C程序】完成从指定数据文件中读入职工的工号和他完成产品个数的数据信息,对同一职工多次完成的产品个数进行累计,最后按如表5-11所示的格式输出职工完
最新回复
(
0
)