ch_08_sum_bio_proc

Introducing Physical Geography (Wse)

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Biogeographic Processes Biogeography explores the distribution of plants and animals on the Earth. This chapter examines how organisms live in ecosystems and how energy and matter is cycled through those ecosystems. This chapter also explores ecological biogeography by examining factors that determine the distributions of organisms in time and space. It examines processes such as evolution, dispersal, and extinction of species through time. Ecology is the study of the interactions between life forms and their environments. An ecosystem is defined as a group of organisms and the environment with which they interact. Both matter and energy are imported into and exported from ecosystems. The food web, or food chain, refers to the flow of food energy between different organisms within an ecosystem. Primary producers are plants and animals that are able to synthesize carbohydrates from carbon dioxide, water and light energy through a process known as photosynthesis. The transfer of food energy to different levels of the food wed is accomplished by consumers which feed on the primary producers or on other consumers. Decomposers (microorganisms and bacteria) feed on decaying organic matter at all levels in the food web. Solar energy is absorbed initially by the primary producers and stored as chemical energy which is available for digestion by consumers. Since on average only ten to fifty percent of the energy at any level is passed on to the next level, the amount of organic matter and consumers must therefore decrease with each level. Photosynthesis is a biochemical reaction which results in the production of carbohydrates and oxygen using water, carbon dioxide, and light energy. A simplified version of this biochemical reaction is: H 2 O + CO 2 + light energy = —CHOH— + O 2 During the respiration process carbohydrates are broken down and combined with oxygen to create carbon dioxide, water, and chemical energy. A simplified version of this chemical reaction is: —CHOH— + O 2 = CO 2 + H 2 O + chemical energy Photosynthesis is dependent on light and heat . Photosynthesis only occurs when light is available and therefore, longer days result in more plant growth. Photosynthesis
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ch_08_sum_bio_proc - Chapter 8 Biogeographic Processes...

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