This document defines key terms related to ecology, including ecosystem, biotic factors, abiotic factors, and biome. It provides examples of ecosystems like deserts, mountains, and coral reefs. The document explains that ecosystems can change daily as biotic and abiotic factors shift and interact in complex ways. Ecosystems are made up of biotic factors like plants and animals as well as abiotic factors like air, water, and sunlight. Major biomes that were listed include desert, grassland, rainforest, and tundra.