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
42
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 paragraph 1, which of the following is true about autotrophs?
选项
A、They use a chemical process to produce their own food.
B、They require plant matter in order to survive.
C、They need producers to provide them with carbon.
D、They do not interact with other organisms in the food chain.
答案
A
解析
转载请注明原文地址:https://kaotiyun.com/show/GxfO777K
0
托福(TOEFL)
相关试题推荐
Completethenotesbelow.WriteNOMORETHANTWOWORDSforeachanswer.Researchingtheoriginofmedievalmanus
Completethenotesbelow.WriteONEWORDONLYforeachanswer.TheTawnyOwlMost【L31】______owlspeciesinUKStronglynocturna
ChooseFOURanswersfromtheboxandwritethecorrectletter,A-G,nexttoquestions37-40.AStudentUnionBuildingBNursery
ChooseFOURanswersfromtheboxandwritethecorrectletter,A-G,nexttoquestions37-40.AStudentUnionBuildingBNursery
Completethesentencesbelow.WriteNOMORETHANTHREEWORDSforeachanswer.Mathbooksarekeptinthe______Building.
Completethenotesbelow.WriteNOMORETHANTWOWORDSforeachanswer.CLIMATEANDARCHITECTURECasesandexamplesarefrom
Completethenotesbelow.WriteONEWORDONLYforeachanswer.ChimpanzeeBehavioursSpeciesWecanfindPanorPanTroglody
ChooseFOURanswersfromtheboxandwritethecorrectletter,A-G,nexttoquestions37-40.AStudentUnionBuildingBNursery
PREPARINGFORASCHOLARSHIPINTERVIEWThewoman,Sophie,wouldliketostudy
A、RecentlydiscoveredmanuscriptsB、SimilaritiesamongreligionsC、MethodsofanalyzingancientmanuscriptsD、Howancientmanusc
随机试题
But________withplayers,executives,andyoungpeople,I’velearnedthatthosewhorisetotheheightsinanyfieldaren’tneces
患者恶寒发热,头身疼痛,无汗,鼻塞流涕,脉浮紧。其舌苔应是
Kennedy一类牙列缺损,采用混合支持式义齿设计时,末端基牙使用应力中断式卡环的主要目的是
女性,45岁,外伤致骨盆骨折、会阴部撕裂伤,术后尿潴留,烦躁不安,最佳的处理方法是
民用建筑节能,是指在保证下列哪些条件的前提下,降低其使用过程中能源消耗的活动()。
下列内容属于我国《合同法》规定的合同履行的基本原则的有( )。
主要功能是协助大脑维持身体的平衡与协调动作的神经系统结构是
Thescientist______mostofhisexperimentsifhehadnotrunshortofhisfund.
Moreteenagerssmoketodaythanatany【C1】______sincethe1970s,afederalstudyshows.Overall,35%ofchildreningrades9—12
Governmentsubsidiescanbeusefulinstrumentsincorrectingmarketfailures____________________(但也能扭曲贸易并激起贸易伙伴的强烈反响).
最新回复
(
0
)