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6 Cards in this Set

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Why is it difficult to classify organism in trophic levels.
Organsims can be secondary, tertiary, and may be quaternary consumers at the same time, such as us humans. It is difficult ot place them on a certain level on the food pyramid.
What is the food web?
Food web displays relationships not a simple hierarchy but rather a complex network, with the various feeding relationships between species existing as connections and the animals themselves as the hubs.
Explain the small biomass and low # of organisms in higer trophic levels
energy is lost between levls in the form of heat (respiration), waste, and dead material. Around 10-20% is passed to the next trophic level
Pyramid of energy
http://upload.wikimedia.org/wikipedia/en/1/1e/EnergyPyramid.png

The arrows demonstrate the direction of energy flow. The units are energy per unit are per unit time. When energy is transferred to the next trophic level, only 10% of it is used to build bodymass, becoming stored energy (the rest going to metabolic processes). As such, in a Pyramid of Energy, each step will be 10% the size of the previous step (100, 10, 1, 0.1, 0.01, etc.).
Describe Ecological Succession using one example.
it is the gradual change in the composition of a community with time in a ecosystem. If sucession occurs in a lifeless area it is primary succession. it can start after things such as volcanoes fire or flood.
Process goes usually like this: lichen, moss, ferns, flowering plants, conifers. An example would be the Volcan Osorno in south Chilie after ash covers the ground: mosses spread over the ash. Small herbs and ferns arrive and through the activity of their roots, soil formation starts to occur. Shrubs and bushes grow and replace these. Then flowering trees grow, then conifers, and other larger trees producing a forest.
Explain the effects of living organisms on the abiotic environment with reference to the changes occurring during ecological succession to climax communities.
Living organisms help soil development. Plant grows, roots grow deeper, break into small particles, helping soil formation. Plants enrich soil with minerals as they die and decompose. PLant roots hold soil particles together, preventing soil erosion and retain nutrients. The water that evaporates from plant leaves condenses and comes as rain. The presence of organic materials in the soil and of roots and root hairshelp retention of water and slow drainage.