Unit 1 – Sustainable Ecosystems and Human Activity Lesson 1 – Life on Earth and Introducing Ecosystems

Life on Earth Of all the planets in the Solar System, Earth is the only one teeming with life. Millions of organisms exist on land and in water on our unique planet.

The Biosphere Earth’s biosphere consists of the zone in, on, and around Earth where life can exist. These places are in the lithosphere, hydrosphere, and atmosphere.

The Biosphere Earth’s atmosphere is the thin layer of gases that surround Earth. It contains gases such as water vapour, oxygen, and carbon dioxide that are necessary for living things.

The Biosphere The lithosphere is the rocky outer shell of Earth. The hydrosphere is the water on, above, and below Earth’s surface. It includes oceans, lakes, ice, clouds, and ground water.

Ecosystems – Complex Systems An ecosystem consists of groups of living things interacting with their non-living environment. The components of an ecosystem are interrelated, which means that changes in one component can affect other components.

Living and Non-Living Living organisms in an ecosystem are biotic factors. Biotic factors include organisms, their waste, their homes, and their remains. Non-living features of an ecosystem are abiotic factors. Weather, water, and rocks are abiotic factors.

Populations and Communities In most ecosystems, there are many different species of plants, animals, fungi, and microorganisms. Biodiversity is the number of different species in an ecosystem. Members of the same species that live in the same ecosystem are a population. E.g. All the snapping turtles in a pond are a population. All the populations of different organisms in an area form a community. E.g. All the turtles, frogs, fish, and aquatic plants in a pond make up a community.

Populations and Communities Individual → Population → Community → Ecosystem BIOSPHERE

Habitat and Ecological Niche A habitat is the place where an organism lives. Terrestrial habitats are found on land. Aquatic habitats are found in the water. Every species interacts with its environment and other species. These interactions are referred to as the species’ ecological niche. The ecological niche of a species includes what it eats, what eats it, where it lives, and how it behaves. No two species have the same niche.