BIO 220 trophic pyramid assignment: a planning guide

Two deliverables and a very small word budget shape everything here. You submit the completed Trophic Pyramid template and a Word document of 250 to 500 words answering six questions, which is roughly forty to eighty words per question. Only the short answer portion goes to Turnitin; both go to the instructor. At that length there is no room for introductions, and each answer should open with its conclusion. Build the pyramid first and completely, because five of the six questions refer back to species you placed in it, and a pyramid with gaps produces answers with gaps. Fill all five levels named in the brief before you write anything: apex predator, tertiary consumers, secondary consumers, primary consumers and primary producers. A level you leave blank because you could not find a species for it is a level you will have to write around in three of the six answers.

The brief pre-empts the commonest mistake by explaining the distinction itself, which is a strong hint that it is regularly got wrong. A biome is a global geographical area sharing climatic conditions, so rainforest, tundra, grassland and desert. An ecosystem sits inside a biome and comprises the living and non-living components of a particular place, so the African savanna within the grassland biome, or Puget Sound tidal zones within the marine biome. Choose an ecosystem, not a biome, and choose one narrow enough that you can name real species at every level. Selecting the desert as your ecosystem will leave you inventing a generic food chain; selecting the Sonoran Desert, or one stretch of it, gives you specific plants and animals to place, and it gives your two references something concrete to be about. Specificity here is not a stylistic preference, it is what makes the rest of the assignment possible.

Question three is the quantitative one and it is where most answers go vague. How did the amount of energy gained compare with the amount lost as heat at the second through fourth trophic levels. The answer is not that some energy is lost. Energy transfer between successive trophic levels is famously inefficient, conventionally quoted at around ten per cent and measured across ecosystems in a range of roughly three to twenty per cent, which means the great majority of the energy at each level never reaches the next one. Most of it is spent on the organism's own metabolism and leaves the system as heat, a consequence of the second law of thermodynamics rather than of anything ecological. Give a figure, name the mechanism, and question six will already be half answered, because the dietary argument at the end of the assignment rests entirely on this number being large.

Questions four and five are linked and answering them together makes both stronger. Question four asks what happens if you remove one species from your pyramid, and question five asks whether saving a species can succeed if preservation focuses on that species alone. The connection is the point: if removing your chosen species cascades through the pyramid, then the species was never separable from the ecosystem in the first place, and a preservation effort aimed at the organism while ignoring its prey, its habitat and its predators is working on the wrong unit. Pick a species for question four whose removal genuinely propagates, which usually means a primary producer or an apex predator rather than something in the middle, and question five writes itself from the answer. If you chose a species in the middle of the pyramid, the honest answer to question four is that other species would take its place, which is a real ecological point but leaves you nothing to build question five on.

Question six asks for a position with rationale, and the rationale is the energy arithmetic you already gave. If roughly ninety per cent of available energy is lost at each transfer, then food produced two levels up from the primary producers embodies far more primary production than food taken directly from them, which is why the same land supports many more people growing crops than raising livestock on it. That is the argument. Whether humans should change their habits is a question you are allowed to answer either way, and a good answer acknowledges what the arithmetic does not settle: land unsuitable for crops, nutritional considerations, cultural and economic realities. State a position, give the energetic reason, and note one limit on it. A rationale that concedes something is more persuasive than one that does not, and the brief asks for rationale rather than for agreement with any particular view.

On mechanics, note the specific requirements rather than assuming the usual ones. A minimum of two references, the GCU Style Guide rather than plain APA, both the pyramid and the document submitted, and the short answer portion uploaded to Turnitin as a Word document. Use credible sources for your species lists, because a trophic pyramid populated from memory will contain organisms that do not co-occur, and a marker who knows the ecosystem will notice. Two references is a floor rather than a target, and one of them should be specific to your chosen ecosystem rather than general to ecology, because the questions about your particular producers and predators cannot be supported from a textbook chapter on trophic levels. Check the GCU Style Guide before formatting them, since it differs from APA in ways that are easy to miss.