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Food Web Food Web

All organisms, dead or alive, are potential food sources for other organisms. A caterpillar eats a leaf, a robin eats the caterpillar, a hawk eats the robin. Eventually, the tree and the hawk also die and are consumed by decomposers. Organisms in an ecological community are related to each other through their dependence on other organisms for food. In a food chain a producer is eaten by a herbivore that is in turn eaten by a carnivore. Eventually, the carnivore dies and is eaten by a decomposer. For example, in a lake, phytoplankton are eaten by zooplankton and zooplankton are eaten by small fish. The small fish are eaten by large fish. The large fish eventually die and decompose. Nothing goes to waste. Food chains are channels for the oneway flow of solar energy captured by photosynthesis through the living components of ecosystems. Food chains are also pathways for the recycling of nutrients from producers, through herbivores, carnivores, omnivores, and decomposers, finally returning to the producers. The perfectly linear relations represented by food chains are almost never found in natural ecosystems. Although all organisms have somewhat specialized diets, most can eat a variety of different foods. Thus, each trophic level appears as part of several different interconnected food chains. These food chains combine into highly complex food webs. As with food chains, a food web's source of energy is the sun. The solar energy is harvested by producers such as green plants or algae. These producers are known as autotrophs or photosynthesizing autotrophs. Almost all other organisms obtain their energy, directly or indirectly, from the sun. The exceptions are the communities found around deep ocean thermal vents, which are supported by various bacteria that convert heat energy into stored chemical energy. These bacteria are known as chemotrophs or chemosynthetic autotrophs. Autotrophs are always found at the first trophic level. In an ecosystem this trophic level may include monerans, protists, and several different phyla of plants. They can all be placed at the first trophic level because they all have the same source of energy, and the entire food web depends on the energy harvested by them. For example, in a grazing food web, a herbivore eats living plant tissue and is eaten in turn by an array of carnivores and omnivores. Herbivores and the carnivores that prey on them are known as heterotrophs. In contrast, a detrivore (also a heterotroph) harvests energy from dead organic material and provides energy for a separate food chain. Each step in a food web or food chain involves a transfer of matter and energy (in the form of chemical bonds stored in food) from organism to organism. Thus food webs are energy webs because the relationships represented by connections in the web represent the flow of energy from a group of organisms at one trophic level to another group of organisms at a different level. Because energy is lost (as waste heat) at each step, food chains rarely involve more than four or five steps or trophic levels. At each level the organisms waste much energy in the form of heat generated by normal activity. Only a fraction is stored as food or used for growth. Only about 10 percent of the food entering a link is available for the next organism in the chain. After about five links, there is insufficient energy to support a population of organisms (other than decomposers). For example, in the food chain starting with diatoms and ending with killer whales, only about 0.01 percent of the initial energy stored by the diatoms is delivered to the killer whales. Energy flow through a food web depends greatly on the nature of the producers at the first trophic level. These are usually photosynthetic plants, phytoplankton, or algae. In forest ecosystems, trees are the largest and most abundant organism. They determine the physical structure of the ecosystem, and they can be eaten directly by small or even very large animals. However, much of the matter and energy harvested by the trees goes to build a supporting structure. These supporting structures are composed of cellulose and other wood fibers that are poor sources of energy (although they may be good sources of valuable minerals and other nutrients). In contrast, grasses do not invest much energy in supporting structures, so more energy is available per kilogram of plant material present to the grazers that obtain energy from plants. Consequently, all of the aboveground parts of the grass plants are eaten by herbivores. Energy spreads out through the food web, from the lowest trophic level to the highest. At the "top of the food chain," large carnivores harvest the remaining energy. However, all things eventually die, no matter where they are in the food web, and the dead organic matter accumulates in the soil, lake bottom, or forest floor. This detritus becomes the basis for a completely different ecosystem, the detritus food web. Detritus feeders and decomposers harvest solar energy from the detritus by breaking down the organic material into simpler organic compounds and inorganic compounds. By this process, the matter is recycled and made available for reuse by plants. The detritus food web is vitally important to all ecosystems on Earth. Without it, dead organic matter would accumulate and bury everything. Humans are omnivores. They can operate on several trophic levels, eating plants, insects, mammals, birds, fish, mollusks, and many other organisms. Humans can also shorten the food chain when resources are scarce. In areas of the world where the population may be straining resources, people commonly increase the total food supply by eliminating one or more steps in the food chain. For example, to obtain more energy humans can switch from eating herbivores that obtain their energy from cereal grains to eating the cereal grains themselves. The food web does not tell us everything there is to know about the complex biological communities called ecosystems. Not all relationships are equally important in these dynamic, evolving communities. Food webs contain both strong and weak links. Weak links can often be broken with little impact on the community. On the other hand, some species have a disproportionately large effect on the community in which they occur. Called key-stone species, they help to maintain diversity by controlling populations of species that would otherwise come to dominate the community. Or they may provide critical resources for a wide range of species. For example, in the intertidal communities of the Northwest Pacific coast of North America, the starfish Pisaster ochraceus feeds on the small mussel Mytilus californius. Experiments have shown that when the starfish is artificially removed, the population of mussels explodes, soon covering all available space. Other species are crowded out. The interaction between Pisaster and Mytilus helps to maintain the species diversity of these intertidal communities. Research has shown that ecological communities with complex feeding relationships have greater long-term stability and are less affected by external stresses. This suggests an evolutionary basis for the diverse and complex ecological relationships found in many communities of organisms. However, humans often violate this sound ecological principle in order to increase agricultural productivity by creating artificial ecosystems that contain only one plant, such as corn. These systems are called monocultures. While greater agricultural productivity is possible with monoculture crops, they are very unstable ecosystems. Disease, drought, or a new insect pest can easily destroy an entire year's harvest. see also Biomass; Feeding; Feeding Strategies; Trophic Level. Elliot Richmond Curtis, Helena, and N. Sue Barnes. Biology, 5th ed. New York: Worth, 1989. Miller G. Tyler, Jr. Living in the Environment, 6th ed. Belmont, CA: Wadsworth, 1990. Purves, William K., and Gordon H. Orians. Life: The Science of Biology. Sunderland, MA: Sinauer Associates, 1987.


From Yahoo Answers

Question:I just need 6 examples. Thanks to whoever answers.

Answers:humans bears apes pigs birds dogs raccoons rodents

Question:

Answers:grass, tree, bush cow, deer, moose shark, wolf, hawk human, bear, raccoon fungi, bacteria, actinolites vulture, fly, cockroaches

Question:im writing a classification essay, and need a thesis staement (topic sentence) any suggestions, then i need a thesis for my next 3 paragraphs...so i need on for each (omnivores. herbivores, and carnivores) i know a little about them but can anyone please elaborate on them?

Answers:Omnivores are any animal that eat anything, humans for example are considered omnivores. Herbivires are animals that only eat plants, nothing else, giraffes for example. And Carnivores are animals that eat pure meat!! Like lions and crap! For a thesis statement you can put: Did you know that not all animals eat the same things?

Question:answer these questions please Introduction What is the omnivore s dilemma and why has does Pollan think it has gotten more complicated recently? Chapter 1 Why does Pollan call Americans people of corn ? What advantages and disadvantages are there to our current corn rich diet? Chapter 2 How has corn changed the look of farms and what is grown there? Why has this change happened? What are the advantages and disadvantages to this type of farming? Chapter 3 Why does Pollan say In terms of energy, the modern farm is a losing proposition ? (pg 32 and chart) Explain the sub-title on pg 37 The High Price of Cheap Corn . Chapter 4 What are some of the challenges caused by the enormous production of corn in America? How have those challenges been solved by companies like Cargill and ADM? What are some potential consequences to the fact that Cargill and ADM have so much control over the production and distribution of corn and the writing of the laws about farming? Chapter 5 Why is it bad for cows to eat corn? Why is it healthy for cows to eat grass? Why is it healthier for humans to eat cows that have been fed grass? Chapter 6 Why is processing food a good thing for food companies like General Mills? Why does Pollan call fake food corn s final victory ? (page 75) Chapter 7 How is corn making us fat? Why does Pollan say the health problems of eating too much hit poor people hardest ? (page 83) Chapter 8 Based on the information in this chapter, provide a more detailed explanation of the omnivore s dilemma and explain why as omnivore s its harder for humans to make smart choices about food. Why does Pollan say that Americans are more susceptible to fad diets? Chapter 9 How much corn was in the Pollan family s fast food meal? Which items contained the most corn? Pollan s chart on page 105 shows a strong correlation between an increase in childhood obesity and an increase in average calories in our food from corn. List other changes to American life and diet since 1971 that may also be contributing to the rise in childhood obesity. Chapter 10 What does the term organic mean in reference to growing food? How is industrial organic different from what Pollan expected organic to be? Why does Pollan say organic lettuce represents a truly amazing amount of energy ? page 125 Chapter 11 Why is it difficult to determine whether or not organic food is healthier than regular food? Use information from both Chap 10 and 11 to explain some of the advantages and disadvantages of growing food in an industrial organic way. Chapter 12 Describe what is meant when Joel Salatin says he is a grass farmer when he actually farms animals and a variety of plants. How does the chart on page 146 help you understand this? Chapter 13 Give an example and explain why biodiversity is valued at Polyface farms. Chapter 14 On page 166, Salatin says that the farm is like an organism. Draw a picture to represent how interconnected the animals, plants and forest are on Polyface farms. Include the cows, broiler chickens, egg chickens, pigs, turkeys, grass, water, and forest. Draw arrows to show connections and write on each arrow how the items are connected. Chapter 15 Make a chart to compare the three different ways to harvest animals (as described in Parts 1,2, and 3) to show how the chicken slaughtering method at Polyface farm different than the others. Chapter 16 Describe three reasons why a shorter food chain (less food miles/a local food economy) is more beneficial than a long food chain. Then do the opposite, describe three reasons why a long food chain is more beneficial. Chapter 17 Pollan writes about how nutrient-rich his meal was from Polyface farms. Why? Explain the difference that grass-fed food makes in terms of the quality of nutrition in the final product. Chapter 18 Define hunter-gatherer. Why did this meal bring Pollan back to the more original omnivore s dilemma? Chapter 19 Describe how some animals evolved to be domestic or to have a relationship with humans and why this is beneficial to both the animals and humans. What do you think would happen if the walls of America s slaughter houses had to be made of glass ? Would this change how people eat? Chapter 20 Why does hunting represent the shortest food chain? Why is this beneficial? What are the challenges in modern society to this short of a food chain? Do you think it is possible for everyone? Chapter 21 Where in the world do we still find hunter-gatherer societies? Why do these societies exist in these places and not everywhere? Ask your history teacher or do a little research into when and how human societies moved away from a hunter-gatherer system. (This is a BIG question, but do your best.) Chapter 22 Pollan talks about how his perfect meal is real i need the answers in 4 DAYS please help

Answers:if you actually read the book all the answers are in there. I mean you really don't know the answer why he refers to us as Children of corn? If you had read the book or even read an abstract you would know the answer to this as, it is a main theme through the book (and modern industrial agriculture itself). You should be able to easily read the book in 4 days and than do your own work and won't have to resort to this lazy sort of cheating that in the end only cheats you out of learning.

From Youtube

Audiobook: The Omnivore's Dilemma: A Natural History of Four Meals by Michael Pollan :Buy full audiobook: www.qksrv.net List of award-winning books/audiobooks: awardwinningaudiobooks.weebly.com The best-selling author of The Botany of Desire explores the ecology of eating to unveil why we consume what we consume in the 21st century. "What should we have for dinner?" To one degree or another, this simple question assails any creature faced with a wide choice of things to eat. Anthropologists call it the omnivore's dilemma. Choosing from among the countless potential foods nature offers, humans have had to learn what is safe, and what isn't, which mushrooms should be avoided, for example, and which berries we can enjoy. Today, as America confronts what can only be described as a national eating disorder, the omnivore's dilemma has returned with an atavistic vengeance. The cornucopia of the modern American supermarket and fast-food outlet has thrown us back on a bewildering landscape where we once again have to worry about which of those tasty-looking morsels might kill us. At the same time we're realizing that our food choices also have profound implications for the health of our environment. The Omnivore's Dilemma is best-selling author Michael Pollan's brilliant and eye-opening exploration of these little-known but vitally important dimensions of eating in America. We are indeed what we eat, and what we eat remakes the world. A society of voracious and increasingly confused omnivores, we are just beginning to recognize the profound consequences of the ...