Ecosystems and environment

The document defines key terms related to ecosystems, including biome, ecosystem, living things, environment, and interactions between living things and their environment. It provides examples of different ecosystem types like forests, grasslands, deserts, rivers, lakes, and seas. Within ecosystems, living things occupy different trophic levels as producers, primary consumers, secondary consumers, tertiary consumers, or decomposers. Ecosystems can be affected by human activities like agriculture, construction, hunting, pollution from insecticides, waste, and fossil fuel combustion, which contributes to issues like global warming and species extinction.