The document defines biomes and ecosystems, describing the six major land biomes - rainforests, deserts, grasslands, deciduous forests, boreal/snow forests, and tundra - as well as two major water ecosystems - freshwater and marine. Each biome is characterized by its climate and common plant and animal species, with examples provided for rainforests, deserts, grasslands, deciduous forests, boreal forests, and tundra. Freshwater ecosystems include streams, rivers, ponds and lakes, while marine ecosystems encompass estuaries, intertidal zones, neritic zones, and the open ocean.