AP Biology Notes - Ch. 54 - TEXTBOOK ASSIGNMENT Chapter 54...

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TEXTBOOK ASSIGNMENT Chapter 54 Food Pyramid: Organization : Trophic levels are the feeding position in a food chain such as primary producers, herbivore, primary carnivore, etc. Green plants form the first trophic level, the producers. Herbivores form the second trophic level, while carnivores form the third and even the fourth trophic levels. In this section we will discuss what is meant by food chains, food webs and ecological pyramids. Trophic levels and the energy flow from one level to the next, can be graphically depicted using three types of ecological pyramids: 1. The Number pyramid shows the number of organisms in each trophic level and does not take into consideration the size of the organisms and over-emphasizes the importance of small organisms. In a pyramid of numbers the higher up one moves, so each consecutive layer or level contains fewer organisms than the level below it. 2. This pyramid indicates the total mass of the organisms in each trophic level. The size of the organism is over- emphasized and it can happen that the mass of level 2 is greater than that of level 1, because the productivity of level 1 is not taken into consideration.
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3. The Energy pyramid indicates the total amount of energy present in each trophic level. It also shows the loss of energy from one trophic level to the next. An energy pyramid shows clearly that the energy transfer from one trophic level to the next is accompanied by a decrease due to waste and the conversion of potential energy into kinetic energy and heat energy. . Feeding Relationships: Autotrophs, the primary producers of the ecosystem, ultimately support all other organisms. o Most autotrophs are photosynthetic plants, algae or bacteria that use light energy to synthesize sugars and other organic compounds. o Chemosynthetic prokaryotes are the primary producers in deep-sea hydrothermal vents. Heterotrophs are at trophic levels above the primary producers and depend on their photosynthetic output. o Herbivores that eat primary producers are called primary consumers. o Carnivores that eat herbivores are called secondary consumers. o Carnivores that eat secondary producers are called tertiary consumers.
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Another important group of heterotrophs is the detritivores, or decomposers. o They get energy from detritus, nonliving organic material such as the remains of dead organisms, feces, fallen leaves, and wood. o Detritivores play an important role in material cycling. Biomass Productivity Primary production can be expressed as energy per unit area per unit time, or as biomass of vegetation added to the ecosystem per unit area per unit time. This should not be confused with the total biomass of photosynthetic autotrophs present in a given time, which is called the standing crop.
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This note was uploaded on 10/01/2011 for the course BIOLOGY 1510 taught by Professor --- during the Spring '11 term at Georgia State University, Atlanta.

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AP Biology Notes - Ch. 54 - TEXTBOOK ASSIGNMENT Chapter 54...

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