Chapter 29

Summary		Questions		Media Resources
29.1 Organisms must cope with a varied environment.
• Organisms employ physiological, morphological, and behavioral mechanisms to cope with variations in the environment.		1.  What are several ways that individual organisms adjust to changes in temperature during the course of a year?		•Biosphere Introduction
29.2 Climate shapes the character of ecosystems.
• Warm air rises near the equator and flows toward the poles, descending at about 30? north and south latitude. Because the air falls in these regions, it is warmed, and its moisture-holding capacity increases. The great deserts of the world are formed in these drier latitudes.		2.  Why are the majority of great deserts located near 30? north and south latitude? Is it more likely that a desert will form in the interior or at the edge of a continent? Explain why.		•Global Air Circulation •Rainshadow Effect - Rain Shadow Effect - Latitude, Elevation and Biome Distribution
29.3 Biomes are widespread terrestrial ecosystems.
• The world's major biomes, or terrestrial communities, can be grouped into eight major categories. These are (1) tropical rain forest; (2) savanna; (3) desert; (4) temperate grassland; (5) temperate deciduous forest; (6) temperate evergreen forest; (7) taiga; and (8) tundra.		3.  What is a biome? What are the two key physical factors that affect the distribution of biomes across the earth?		•Biomes/Climate • Soils •Land Biomes •Tropical Forests •Temperate Forests •Savages by Kane •Classification of Biomes
29.4 Aquatic ecosystems cover much of the earth.
• The ocean contains three major environments: the neritic zone, the pelagic zone, and the benthic zone. • The neritic zone, which lies along the coasts, is small in area but very productive and rich in species. • The surface layers of the pelagic zone are home to plankton (drifting organisms) and nekton (actively swimming ones). The productivity of this zone has been underestimated because of the very small size (less than 10 mm) of many of its key organisms and because of its rapid turnover of nutrients. • The benthic zone is home to a surprising number of species. • Freshwater habitats constitute only about 2.1% of the earth's surface; most are ponds and lakes. These possess a littoral zone, a limnetic zone, and a profundal zone. The waters in these zones mix seasonally, delivering oxygen to the bottom and nutrients to the surface.		4.  What is the difference between plankton and nekton in the ocean's pelagic zone? How important are the photosynthetic plankton to the survival of the earth? Is the turnover of nutrients in the surface zone slow or fast? 5.  What conditions of the abyssal zone led early deep-sea biologists to believe nothing lived there? What provides the energy for the deep-sea communities found around thermal vents? What kind of organisms live there? 6.  Does much diversity occur in the abyssal zone? How are such ecosystems supported in the absence of light? 7.  What is the difference between a eutrophic and an oligotrophic lake? Why have humans increased the frequency of lakes becoming eutrophied?		•El Nino Southern Oscillation • Aquatic Systems • Exotic Species and Freshwater Ecology • Our Winters May Get Colder - Marine Ecosystems - Thermal Stratification

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