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Jeany's assignment



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  • 1. How do plants obtain the nitrogen they need? Best Answer - Chosen by Asker *Some plants (like legumes - ie peas) form a relationship with microorganisms (Rhizobium sp.). This happens in their roots, and nodules are formed. these microbes can take nitrogen from the air (which is about 80% nitrogen) and turn it into ammonia, which is absorbed by the plants root. *they absorb it in dissolved form from the water in the soil as NH4+ or as NO3- *Plants must have nitrogen in the form of nitrates or ammonia. They get these from the soil where they are taken up by the roots. How do herbivores obtain the nitrogen they need? Herbivores obtain nitrogen just like any other animal - through the air, which is mostly composed of nitrogen. However, organic nitrogen that can be used in proteins is only found in autotrophs. Through the nitrogen cycle, atmospheric nitrogen is fixed as organic nitrogen which is assimilated by plants. Herbivores, like omnivores and carnivores, get their nitrogen from food. The trick is getting the nitrogen "fixed" into the food in the first place. About 80% of earth's atmosphere is nitrogen, but atmospheric nitrogen is very nearly inert (the triple bond between the nitrogen atoms is difficult to break). It does not readily engage in chemical reactions, so plants and animals cannot get their nitrogen by breathing. Oxygen, on the other hand, reacts easily, so you'll find that you can get the oxygen you need directly from the atmosphere. Plants extract carbon directly from the atmosphere--from carbon dioxide and photosynthesis. That carbon, plus water and some other ingredients, produce the carbohydrates and other nutrients we get from plants. But like us, plants can't capture atmospheric nitrogen. They have to get the nitrogen they need for proteins & DNA from another source. So how does nitrogen get fixed into plants? Primarily via nitrogen compounds in the soil. There is a bit of nitrogen in any soil, thanks to decaying plants & animals and the activity of certain types of bacteria. But if you farm the soil intensively, you can quickly exhaust the naturally occurring nitrogen. One way to build up the nitrogen in soil is to exploit a symbiotic relationship between certain types of bacteria and a few types of plants. Bacteria that grow on the roots of some bean plants convert atmospheric nitrogen into compounds that stay in the soil. This is the phenomenon behind crop rotation with soy beans--you let the bacteria on the soy bean's root replenish the nitrogen in the soil. Then crops you grow in that soil pass that nitrogen through the food chain. For example, an herbivore might eat the crop directly, or a carnivore could eat the flesh of an herbivore that ate the crop that grew in the field that once grew soy beans that hosted nitrogen-fixing bacteria. Another way to get the nitrogen into the soil is via animal waste. Manure contains a good deal of fixed nitrogen. Hence the smell that bothers city folk when they visit farm country.
  • 2. Today, a good deal of the nitrogen in crops comes from manufactured fertilizer. The Haber-Bosch chemical process, developed about a hundred years ago, draws nitrogen from the air and fixes it in forms that can be used for fertilizer (or explosives.) About half of the nitrogen in your body came from the atmosphere via the Haber-Bosch process. (See "The Alchemy of Air" by Thomas Hager, 2008, for more on the history of Haber-Bosch.) Without Haber-Bosch, a couple billion of us humans would not be alive. What would be the impact on the nitrogen cycle if there were a decrease in decomposition in a given ecosystem? The nitrogen cycle is of particular interest to ecologists because nitrogen availability can affect the rate of key ecosystem processes, including primary production and decomposition. The Nitrogen Cycle The nitrogen cycle is the process by which nitrogen is converted between its various chemical forms. This transformation can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation, ammonification, nitrification, anddenitrification. The majority of Earth's atmosphere (78%) isnitrogen, [1] making it the largest pool of nitrogen. However, atmospheric nitrogen has limited availability for biological use, leading to a scarcity of usable nitrogen in many types of ecosystems. The nitrogen cycle is of particular interest toecologists because nitrogen availability can affect the rate of key ecosystem processes, including primary production anddecomposition. Human activities such as fossil fuel combustion, use of artificial nitrogen fertilizers, and release of nitrogen in wastewater have dramatically altered the global nitrogen cycle [citation needed] . A 2011 study found that nitrogen from rocks may also be a significant source of nitrogen, that had not previously been included in most calculations and statistics. [2][3][4] Autotroph An autotroph [α] ("self-feeding", from the Greek (e)autos "self" and trophe"nourishing") or "producer", is an organism that produces complex organic compounds (such as carbohydrates, fats, and proteins) from simple substances present in its surroundings, generally using energy from light (photosynthesis) or inorganic chemical reactions (chemosynthesis). They are the producers in a food chain, such as plants on land or algae in water. They are able to make their own food, and do not need a living energy or organiccarbon source. Autotrophs can reduce carbon dioxide to make organic compounds, creating a store of chemical energy. Most autotrophs use water as the reducing agent, but some can use other hydrogen compounds such as hydrogen sulfide. Phototrophs, a type of autotroph, convert physical energy from sunlight (in case of green plants) into chemical energy in the form ofreduced carbon. Autotrophs can be phototrophs or chemotrophs. Phototrophs use light as an energy source, while chemotrophs utilize electron donors as a source of energy, whether from organic or inorganic sources; however in the case of autotrophs, these electron donors come from inorganic chemical sources. Such chemotrophs are lithotrophs. Lithotrophs make use of inorganic compounds, such as hydrogen sulfide, elemental sulfur, ammonium andferrous iron, as reducing agents for biosynthesis and chemical energy storage. Photoautotrophs and lithoautotrophs use a portion of the ATP produced during photosynthesis or the oxidation of inorganic compounds to reduce NADP + to NADPH in order to form organic compounds. [1]
  • 3. Heterotroph A heterotroph (/ˈhɛ tərɵ troʊ f/; ἕ τερος heteros = "another", "different" and τροφήtrophe = "nutrition") is an organism that cannot fix carbon and uses organiccarbon for growth. [1] This contrasts with autotrophs, such as plants and algae, which can use energy from sunlight (photoautotrophs) or inorganic compounds (lithoautotrophs) to produce organic compounds such as carbohydrates, fats, and proteins from inorganic carbon dioxide. These reduced carbon compounds can be used as an energy source by the autotroph and provide the energy in food consumed by heterotrophs. Herbivore A herbivore is an animal anatomically and physiologically adapted to plant material, for example foliage, as the main component of its diet. These animals have an all plant diet and have characteristics that are special for obtaining plant material. (ex. Teeth for chewing tough plant parts) Carnivore A carnivore /ˈkɑ rnɪ vɔ ər/ meaning 'meat eater' (Latin, caro meaning 'meat' or 'flesh' and vorare meaning 'to devour') is an animal that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animaltissue, whether through predation or scavenging. [1][2] Animals that depend solely on animal flesh for their nutrient requirements are considered obligatecarnivores while those that also consume non-animal food are consideredfacultative carnivores. [2] Omnivores also consume both animal and non-animal food, and apart from the more general definition, there is no clearly defined ratio of plant to animal material that would distinguish a facultative carnivore from an omnivore. [3] A carnivore that sits at the top of the foodchain is an apex predator. Plants that capture and digest insects are called carnivorous plants. Similarly,fungi that capture microscopic animals are often called carnivorous fungi. Omnivore An omnivore, meaning 'all-eater' (Latin omni, vorare: "all, everything", "to devour"), or polyphage ("many eater") species is a consumerof a variety of material as significant food sources in their natural diet. These foods may include plants, animals, algae and fungi. [1] Omnivores often are opportunistic, general feeders with neither carnivore nor herbivore specializations for acquiring or processing food, and are capable of consuming and do consume both animal protein and vegetation. [2] Many omnivores depend on a suitable mix of animal and plant food for long-term good health and reproduction. What is Decomposers? Decomposers (or saprotrophs) are organisms that break down dead or decaying organisms, and in doing so carry out the natural process ofdecomposition. [1] Like herbivores and predators, decomposers areheterotrophic, meaning that they use organic substrates to get their energy,carbon and nutrients for growth and development. Decomposers can break down cells of other organisms using biochemical reactions that convert the prey tissue into metabolically useful chemical products, without need for internal digestion. [2] Decomposers use dead organisms and non-living organic compounds as their food source.
  • 4. What trophic level do decomposers belong to? Decomposers belong to the last trophic level, since they consume the dead organisms, its around the fourth or fifth level. Decomposers are last in food chains, so they can be 4th or 5th trophic level depending upon the food chain or food web: -producers -primary consumers -secondary consumers -ter. or quatr. and so on consumers -decomposers Why do food chains usually only have 3-5 levels? Best Answer - Chosen by Asker Because at each trophic level, 90% of the total energy is lost through basic body functions. The higher up on the food chain you are, the less energy there is available. Ten percent rule: only ten percent of the energy in any trophic level is available for the next trophic level. The higher you feed in the food chain the less energy is available. Because a huge amount of energy is lost in between each level. Something around 80%, I believe. Whats the difference between a food chain and a food web? Best Answer - Chosen by Voters A food chain is a single line of organisms, where each is preceded by something that it consumes and is followed by something that consumes it. A food web branches out in all directions with arrows pointing from organisms to any number of organisms that consume it. The food chain refers to a natural system by which energy is transmitted from one organism to another. When we refer to these systems on an ecological basis, we use the term food web. A food chain refers to four main parts. These are: * The sun – this is the primary source of energy for all organisms * The producers – these are the plants. They are called producers because they are the only part of the food chain that produces their own food, as well as the food for other organisms. In fact, the oxygen that all living things breathe in is a result of the food producing process of the plants (photosynthesis). The food
  • 5. that other organisms take in is also a result of the photosynthesis in plants that produces glucose. * The consumers – this refers to the group of organisms that eat something else. They may be herbivores (plant eating animals) or carnivores (flesh eating animals). They also include parasites and scavengers. * The fourth in the food chains are the scavengers. These are the fungi and bacteria that we look down on with such disgust. They are an all important part of the food chain because they convert all dead matter into nitrogen and carbon that is released into the atmosphere. Without the hard work put in by these scavengers the earth would just be one large garbage bin that was never emptied! A food web on the other hand refers to a bunch of food chains that make up an ecosystem. It is a mass of connected food chains that are interlinked at various points. For instance, there may be links running between grass and all the animals that eat grass e.g. the goat, cow etc. Then there would be a link between those animals and other animals that ate them, for instance the lion, humans etc. A food chain describes a pattern through which energy is transmitted from the producers or the plants to the decomposers. For instance, it would perhaps describe how a tiny fish survive on plankton, while the larger ones survive on them. A food web on the other hand would also include the big fish that were feeding on the plankton as well. It basically depicts a broader picture of all interconnected food chains that exist within an ecosystem. A food chain is a description of a single link between the origin of the source of energy and its final recipient. A food web includes all such chains that make
  • 6. up an ecosystem. It can be described as a collection of individual and interlinked food chains! Both food chains and the food web have been adversely affected by the onslaught of human civilization. In order to make our habitat more ‘conducive’, we are causing the destruction of valuable parts of the food chain and the food web. For instance, the use of pesticides is having an adverse effect on most of the eco systems. Man must realize that they are a part of the food chain and that their welfare is dependent on others also! Examples Autotrophs plants autotrophic bacteria algae flowers moss Grass Algae Trees Moss Cactus Basically any type of plant that produces its own food. Heterotroph (some exampls: zebras, fish, lizards, lions, toucans, koalas, giraffes, deer, tigers, foxes, crocodiles, sting rays, penguins, walruses, otters, badgers, sea lions, beavers, dolphins, antelope, chickens, rabbits, etc.) Herbivore
  • 7. Sloths Kangaroos Caterpillars Termites Sheep Deer Rabbits Cows Buffalo Rhinoceros Elephants Eland Dick Dick Goats Geese Carnivore Carnivores: Canrnivores are the animals which purely feed on flesh of other animals. Here are some examples of animals that are carnivores: alligators Bald Eagle cayman Crocodiles dinosaurs hawks Hyena Lion octopus Otter panthers penguins
  • 8. pumas sharks spiders Tigers Tiger shark Wolf A carnivore is an animal that gets food from killing and eating other animals; they literally live on other animals. Omnivore An omnivore is an animal which eats both meat and plant matter. Examples would be Bears, Hedgehogs, Pigs, Rats, Chickens and Piranhas. Hedgehog , possum, Pigs, Chimpanzee , raccoon, skunk, sloth , CHICKEN, some lizards, humans, cat, raven, and roadrunner.