Biotic and Abiotic

Georgi Stoyanov BIOL1202 11/25/08 Taskstream Assignment 4 to survive and reproduce. Some abiotic factors are water availability, light intensity and level of pollutant. Biotic factors are all the living things or their materials that directly or indirectly affect an organism in its environment. This would include organisms, their presence, parts, interaction, and wastes. Some biotic factors are parasitism, disease, and predation. The difference is that biotic are living and abiotic are non-living. Abiotic factors change habitat characteristics and may determine the way and /or intensity of biotic interactions among and between natural populations. Abiotic factors and biotic influences interact between each other and change each other. We can say they're interdependent. a. In ecology, energy flow (calorific flow) refers to the flow of energy through a food chain. Solar energy is fixed by the photoautotrophs, the so called primary producers, like green plants which fix the energy in forms such as glucose and ATP by photosynthesis. The primary consumers consuming these photoautotrophs are herbivores. They absorb most of the stored energy in the plant through digestion, and transform it into the form of energy they need, adenosine triphosphate, through respiration. A part of the energy received by the herbivore is converted to bodily heat (an effect of respiration), which is radiated away and lost from the system. Energy loss also occurs in the expulsion of egesta, which contains undigested energy compounds. Secondary Consumers then consume the primary consumers. Energy that had been used by the primary consumers for growth and storage is thus absorbed into the secondary consumers through the process of digestion. As with primary consumers, secondary consumers convert this energy into a more suitable form (ATP) during respiration. Again some energy is lost from the system, since energy which the primary consumers had used for respiration cannot be utilized by the secondary consumers. Tertiary consumers then consume the secondary consumers, and most of the energy is passed along, while some is again lost in the ways described above and below. A final link in the food chain is decomposers which break down the organic matter of the tertiary consumers (or whichever consumer is at the top of the chain) and release nutrients into the soil. Decop Saprotrophic bacteria and fungi are decomposers, and play a pivotal role in the nitrogen and carbon cycles. The energy is passed on from trophic level to trophic level and each time some (about 90%) of the energy is lost, with some being lost as heat into the environment (an effect of respiration) and some being lost as egesta. This means the top consumer of a food chain receives the least energy, as a lot of the food chain's energy has been lost between trophic levels. This loss of energy at each level limits typical food chains to only 4-6 links. b. Essential plant nutrients: there are at least 16 essential chemical elements for plant growth. Carbon elements. Nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), boron (B), molybdenum (Mo), and chlorine (Cl) are obtained from the soil and required by all plants. Sodium (Na), silicon (Si), and nickel (Ni) are essential elements for some plant species and, although not required, have positive or beneficial effects on the growth of other species. Cobalt (Co) is essential for nitrogen fixation by legumes. Additional elements, such as selenium (Se), arsenic (As), and iodine (I) are not required by plants, but can be important in plant nutrition since they are essential nutrients for humans and other animals that consume plants. In ecology and Earth science, a biogeochemical cycle is a circuit or pathway by which a chemical element or molecule moves through both biotic ("bio-") and abiotic ("geo-") compartments of an ecosystem. In effect, the element is recycled, although in some such cycles there may be places (called "reservoirs") where the element is accumulated or held for a long period of time. The elements, chemical compounds, and other forms of matter are passed from one organism to another and from one part of the biosphere to another through the biogeochemical cycles. All chemical elements occurring in organisms are part of biogeochemical cycles. In addition to being a part of living organisms, these chemical elements also cycle through abiotic factors of ecosystems such as water (hydrosphere), land (lithosphere), and the air (atmosphere); the living factors of the planet can be referred to collectively as the biosphere. All the chemicals, nutrients, or elements — such as carbon, nitrogen, oxygen, phosphorus — used in ecosystems by living organisms operate on a closed system, which refers to the fact that these chemicals are recycled instead