| Ecosystem | structure and function | HPU BSc 1st year

General introduction Structure of ecosystem Biotic Components Abiotic Components Functions of Ecosystem Energy Flow Trophic structure Food Chain Food Web Ecological Pyramids Study of relationships between living organisms and their environments. Term was coined by A.G. Tansley, 1935. Is a functional unit comprising all the organisms in a particular place interacting with one another and with their physical environment. Interconnected by ongoing flow of energy and cycling of materials. Visualized as functional unit of nature. Has all the components: biological and physical necessary for survival. It is a self sustainable system. BIOTIC COMPONENTS Autotrophs/Producers: organisms that can manufacture their own food from simple inorganic compounds. Ultimate source of organic compounds for all heterotrophs, refer as the producer of biosphere. Two types: Photoautotrophs: make their food through photosynthesis. Chemotrophs: Some microbes produce organic matter to some extent by oxidation of certain chemicals in the absence of light known as chemosynthetic or chemotrophs. CONSUMERS Can not synthesize their own food and eat or depends upon other organisms known as heterotrophs. Depends directly or indirectly on the organic matter produced by producers. All animals are heterotrophs: Some feed upon green plants (herbivores), some eat flowers or their nectar (nectarivores), some live on fruits (frugivores), some kill and eat other animals (carnivores). Omnivores: feed on plants and animals. Detrivores: feed on parts of dead decaying organisms, wastes of living organisms commonly known as saprotrophs.