L3 Energy Flow in the Ecosystems PDF

Objectives Define ecology, Enumerate biotic and Illustrate the flow of environment, habitat abiotic factors in an energy in a food web. and niche....

Objectives Define ecology, Enumerate biotic and Illustrate the flow of environment, habitat abiotic factors in an energy in a food web. and niche. ecosystem. Distinguish among Recognize the different Distinguish among mutualism, process that occur in the producers, consumers, commensalism, biogeochemical cycles. and decomposers. predation and parasitism. Trophic Structures Trophic Structure Transfer of matter and energy occur between organisms or between organisms and the physical environment represented by a trophic structure. Energy flow between organisms occurs in food chains, in which energy from food passes from one organism to the next in a sequence. Trophic Structure Each level, or “link,” in a food chain is a trophic level. (The Greek tropho means “nourishment”). Food web, on the other hand, is a complex of interconnected food chains in an ecosystem. All food chains and webs start with the sun, the ultimate source of energy here on Earth. Trophic Structure Organisms can be classified based on their general nutritional habits. Trophic Structure 1. Producers, also called autotrophs (self-feeders), are organisms that can manufacture their own organic compounds that they use as sources of energy and nutrients. Most producers are green plants that make organic nutrients by transforming energy from the sun into chemical energy through photosynthesis (photosynthetic organisms). Trophic Structure 1. Producers Chemosynthetic organisms, mostly bacteria, can extract inorganic compounds, such as hydrogen sulfide, from their environment and convert them to organic nutrients in the absence of sunlight through the process called chemosynthesis. Trophic Structure 2. Consumers – Organisms that get the nutrients and energy they require by feeding either directly or indirectly on producers. They are also called heterotrophs (“other-feeders”). Trophic Structure 2. Consumers Primary consumers are herbivores (plant-eaters) which feed directly and only on all or part of living plants Secondary consumers are primary carnivores (meat- eaters), which feed only on plant- eating animals Tertiary and higher-level consumers include large carnivores or omnivores (plant- and meat-eaters) that feed on primary and secondary consumers and/or producers. Trophic Structure Detritivores – Heterotrophs that feed on detritus, or dead organic plant and animal matter. There are two major classes of detritivores: Trophic Structure Detritivores 1. Detritus feeders – ingest fragments of dead organisms and their cast-off parts and organic wastes. Examples are crabs, earthworms and clams. 2. Decomposers – absorb and endocytose the soluble nutrients at the cellular level. This saprophytic mode of nutrition is carried out by bacteria and fungi.