Hi ! I Would like to know what is a trophic cascade?
357224
I'll assume you mean a trophic cascade in terms of cell biology.  A ligand-mediated event, such as any binding of a hormone, cytokine, or trophic factor, causes a "cascade' of intracellular reactions that serves to amplify the signal.  So, if only one molecule of, say, TNF binds to it's receptor, that may activate an enzyme that alters 100 other proteins.  Each of those 100 other proteins may in turn be enzymes (and often are), and each may then alter 100 proteins-thus from a single binding event at the cell surface, we very rapidly (within seconds) have 10's or 100's of thousands of proteins effected, which in turn effects the function of those proteins.  This is a typical cascade of any ligand-receptor interaction. Now trophic means that it aids in growth or survival of the cell, so a trophic cascade would be one in which a trophic factor, such as nerve growth factor, binds to the receptor on the cell and induces changes in that cell which aid it in surviving and functioning.
80148
the producers in an ecosystem are the plants, they convert light energy into organic chemicals, that higher levels(herbivores,carnivores) eat. also in aquatic ecosystems the producers are photosynthetic bacteria or protozoa.
466258
it is called biogeometry & use the link to know more
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invertebrate\n\nmore info at\nhttp://www.ipm.ucdavis.edu/WATER/U/ceriodaph.html
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Heterotrophs are organisms which do not make their own food and instead use the food prepared by the autotrophs or the producers.There are three types of heterotrophic nutrition:\n\n1.Saprophytic:In this mode of nutrition,the organisms depend upon the dead and decaying organic(containing carbon or carbon chains) matter.they derive their nutritio from thesesaprophytic heterotrophs depend on dead, decaying organic matter. There are many species of saprophytic bacteria and fungi. Saprophytic decay bacteria and fungi are essential decomposers which recycle vital nutrients back into the ecosystem. .\n.eg - mushrooms,etc.\n\n2.Parasitic:In this mode of nutrition the organism dosn't pre[are its own food.It derives its food from some other organism.The organism fom which it derives its nutrition is called the host.eg\nParasitic nutrition: e.g. taenia (taenia solium - tapeworm). This is an endoparasite, with two hosts. The adult form is found attached on the inside of human intestines, the larval form is found in the pig. The adult is made up of segments called proglottides. At one end is the scolex, which has a double row of hooks and 4 suckers to attatch to the hosts intestine. Lower segments self fertilise and are released in the hosts faeces. It has no digestive system or enzymes it directly absorbs predigested nutrients straight into its body. It has a thick outer coating (tegument) made of protien and chitin, which protects it from the hosts enzymes. It can survive in low oxygen levels. It causes little damage in healthy humans.\n\nHolozoic:Organisms that are holozoic are consumers. Primary consumers are herbivores and Secondary consumers are carnivores, some organ isms feed on both plants and animals and are called omnivores.. Each are specifically adapted to their particular type of nutrition:\n\nHerbivores: e.g. cattle and sheep are herbivores and ruminants. Ruminants digestive systems allow a high proportion of cellulose to be digested. Ruminants have 4 stomachs (rumen, reticulum, omasum and abomasum).\n\n1) food is swallowed and lands in the rumen. This contains bacteria and some protoists annd yeasts. Food remains here for upto 30 hrs. The food is often regurgitated to be chewed again (chewing the cud). The microbes break down the cellulose (with cellulase), into hexoses (breaks poly saccaride b-link). These hexoses are then fermented in anaerobic conditions into organic acids, alos alot of CO2 and methane are belched.\n2) Next food enters the reticulum, sometimes food enters here first. Food moves between the rumen and reticulum fairly freely.\n3) As the food enters the omasum, where water and organic acids are removed. No enzymes are secreted.\n4) From here on it follows a similar path as in the human gut, with enzymes being secreted etc.\n\nNB. many of the bacteria etc are also taken in with the food and digested, which makes protien digestion from the rumen even more efficient, as the microbes can convert low grade protien and urea into a high grade version that can be digested by the cow.\n\nCarnivores: e.g. cat or dog. Their digestive system is more or less the same as humans. The greatest differences being in theeir dentition and other physical and behavioural adaptations which aid their hunting.
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heterotrophs are the organisms that depend on other organisms for food.eg-human\nautotrophs are the organisms which can prepare their own food.
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Food chains describe the feeding relationships in a biotic community. It is also called the energy chain because it describes the flow of energy and material from one species to another ie from plants to animals.\n\nA food chain describes a simple flow of material. It starts with the plant and algae who convert energy from the sun and ends with a top predator. For the Arctic or Southern ocean, a food chain may run as follows: Plankton-Copepod (small animal that feeds on plankton-fish-squid-orca.\n\nBecause energy is lost at each level, the number of levels in the chain does not normally exceed four or five. In overpopulated areas, people often cut one step from the food chain by eating grains themselves rather than feeding them to livestock. This increases the amount of food available. The loss of energy also explains why there are more plants and algae than herbivres and more herbivores than carnivores.\n\nThe food chain often doesn't reflect the complex relationships within an ecosystem. In reality, you have a complex flow of relationships. To reflect this, you have a food web or foot network that shows a complex flow of relationships. (I assume this is what you mean by a food pyramid which is normally related to human diet).\n\nGood luck with the report.
197594
this is the table you must know \nsun->primary consumers->secondary consumers->turshic consumers->decomposers . this clearly states that consumers get energy from one level down to them and decomposers get energy from consumers
1026025
I'm not certain anyone but a biologist can answer this one correctly, but I'll take a stab: the organisms in any ecosystem are related to each other in a hierarchy, like a food chain. Other relationships are helping, symbiotic or parasitical relationships in which one organism's function allows another to live. An ecosystem thrives when all its organisms are in balance.
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In ecology, the word ecosystem is an abbreviation of the term, ecological system. Some consider this the basic unit in ecology.\n\nIn general terms an ecological system can be thought of as an assemblage of organisms (plant, animal and other living organisms—also referred to as a biotic community or biocoenosis) living together with their environment (or biotope), functioning as a loose unit. That is, a dynamic and complex whole, interacting as an "ecological unit".\n\nEarly conceptions of this unit were as a structured functional unit in equilibrium. This equilibrium was characterized by energy and matter flows between its constituent elements. Others considered this vision limited, and preferred to understand an ecosystem in terms of cybernetics. From this view an ecological system is not a structured functional unit in equilibrium, but a functional organisation at dynamic equilibrium, or what was also called steady state. This branch of ecology that gave rise to this view has become known as Systems Ecology. Steady state is understood as the phase of an ecological systems evolution when the organisms are "balanced" with each other and their environment. This balance is achieved through various types of symbiosis, such as predation, parasitism, mutualism, commensalism, competition, and amensalism. Introduction of new elements, whether abiotic or biotic, into an ecosystem tend to have a disruptive effect. In some cases, this can lead to ecological collapse and the death of many native species. The abstract notion of ecological health attempts to measure the robustness and recovery capacity for an ecosystem. That is, how far the ecosystem is away from steady state.\n\nThe size and scale of an ecosystem can vary widely. It may be a whole forest, as well as a small pond, or even the geobiosphere itself. Different ecosystems are often separated by geographical barriers, like deserts, mountains or oceans, or are isolated otherwise, like lakes or rivers. As these borders are never rigid, ecosystems tend to blend into each other. As a result, the whole earth can be seen as a single ecosystem, or a lake can be divided into several ecosystems, depending on the scale used.
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Mutualism- A symbiotic relationship in which both species benefit.\n\nParasitism- A symbiotic relationship in which one organism derives benefit at the expense of the other.\n\nSo.... figure out animals that live in a tundra that have these different relationships. I'm not sure what kinds of animals you would find in a place like that. Sorry I can't be of anymore help.
353801
The answer is (D) the hawk.\n\nThe concept you are asking about is called biological magnification.  As energy flows through the food chain, there is significantly less energy available to each trophic level.  To accommodate, the organisms must eat a higher biomass from the trophic level below it.  Therefore, each level of the food chain accumulates higher amounts of DDT in their system.  Because the hawk is the third-order consumer in the example provided, it will have the highest concentration of DDT.\n\n<edited for spelling>
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Mutualism is a relationship between organisms where both benefit.  In the tundra a classic example of this is the relationship between algae and lichen growing on rocks.  The algae provides sugars for the lichen while the lichen provides a solid substrate for the algae to thrive on.
1077625
study the food chain.
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One common name for this is "nutrient overload" and it is responsible for things like algal blooms and eutrophication of the water. \nI think  it's the term "eutrophication" you are after:\nhttp://toxics.usgs.gov/definitions/eutrophication.html\n\n"Eutrophication is a process whereby water bodies, such as lakes, estuaries, or slow-moving streams receive excess nutrients that stimulate excessive plant growth (algae, periphyton attached algae, and nuisance plants weeds)."
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I took this from wikipedia. It's for reference!!\n\nAn ecosystem, a contraction of "ecological" and "system", refers to the collection of components and processes that comprise, and govern the behavior of, some defined subset of the biosphere. The term is generally understood to refer to all biotic and abiotic components, and their interactions with each other, in some defined area, with no conceptual restrictions on how large or small that area can be. \nIn biology, Abiotic components are nonliving chemical and physical factors in the environment. Often, these are described as light, temperature, water, atmospheric gases, wind as well as soil (edaphic) and physiographic (nature of land surface) factors.\nThese factors could be said to be the definitions for the exact environmental conditions in which plants need to grow.\nOxygen, carbon dioxide, and nitrogen are the most commonly described gasses; and the wind, soil, and physiographic conditions can also combine in multiple ways to affect organisms.\nIn general terms an ecological system can be thought of as an assemblage of organisms (plant, animal and other living organisms—also referred to as a biotic community or biocoenosis) living together with their environment (or biotope), functioning as a loose unit. That is, a dynamic and complex whole, interacting as an "ecological unit."\n\n\nOther population ecologists, stochastists, (den Boer & Reddingius, 1996), view an ecosystem as an expression of stochastic events, and corresponding responses from organisms. Thus, ecosystems result from the sums of infinite individual responses of organisms to stimuli from non-living and living elements in the environment. The presence or absence of populations merely depends on reproductive and dispersal success and population levels fluctuate in response to stochastic (chance) events. As the number of species in an ecosystem is higher, the number of stimuli is also higher.\n\nCheck the link for more info you need. I'm not familiar with this, besides basic info but hopefully this helps.
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Dead plants and animals cannot be said to occupy a level in the food chain as being dead they are not able to eat and therefore occupy the lowest space on the trophic level  as food for fungus, microbes, insects, animals and other plant life.\n\nStrange question.