BIOLOGY: Sustainable Ecosystems and Human Activity The Earth’s biosphere is all places on Earth where living things can exist. It includes the following: a) Atmosphere – the thin layer of gases that surrounds the planet. It contains gases such as oxygen, carbon dioxide and water vapour that are necessary for living organisms. b) Lithosphere – the rocky outer shell of the earth. It is made up of soil, mountains, forests deserts etc. c) Hydrosphere – the water on, above and below the Earth’s surface. It includes oceans, lakes, ice, clouds and groundwater. ECOLOGY – The study of how living organisms interact with each other as well as with their environment. ECOSYSTEM – A complex system made up of living things and their nonliving environment. Populations are made up of members of the same species living in the same ecosystem. All populations of different organisms living in the same environment form a community. All living things in an ecosytems are affected by two types of factors: biotic – a factor in an ecosystem created by the presence and roles of other living things for example plants and animals abiotic – a factor in an ecosystem created by non-living agents for example sunlight, temperature, and wind ** Biotic and abiotic factors have an impact on one another.