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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.