Interactions and Ecosystems Grade 7 Science Ms. Lyons
Transcript Interactions and Ecosystems Grade 7 Science Ms. Lyons
Interactions and Ecosystems
Grade 7 Science
Topic 1: Interactions Within
• Ecology: The study of the relationships
between living organisms and their
• Scientists who study these relationships
are called ecologists.
The Needs of Living Things
• All living things from spiders, to
sunflowers, to humans need…
Air (gas exchange)
• Adaptation: is an inherited characteristic
that helps an organism survive and
reproduce in its environment.
• E.g. A duck has webbed feet so it can
• E.g. Many birds have hollow bones so they
can fly easily.
• There are however many characteristics
that help animals survive in their
environment that are learned.
• E.g. Humans learn to look both ways
before crossing the street.
• These however, are not adaptations.
• An ecosystem is the interactions between living and
non-living things in a particular environment.
• E.g. A rotting log is an example of an ecosystem. The organisms living in
and on the log and the soil, temperature, and other non-living features
around the log are interacting.
Interactions Between Living Things
in an Ecosystem
• Symbiosis: Occurs when two species live
closely together in a relationship that lasts
• Can you think of any examples??
3 Types of Symbiosis
• Mutualism: Each partner benefits from
• e.g. The remora fish uses suckers on its head to
attach itself to a shark. It then eats the bacteria
living on the shark’s skin.
• Parasitism: One partner benefits from
the relationship and the other is harmed.
• Which is which?? Parasite or host??
Examples: tapeworm, mosquito, leech
• Commensalism: One partner benefits
and the other appears to be unaffected
• The orchid plant lives high up attached to the trunks of
trees. The orchid benefits by having a safe place to live,
the tree does not benefit or suffer.
• Other Examples???
Impacts on Ecosystems
• Relationships exist between the living and
non-living. These can have a major impact
on an environment.
• The beaver can have a dramatic impact on water and
change the environment around them by building dams.
Topic 2: Human Impacts on
• Humans have a more dramatic and often more
devastating effect on the Earth’s ecosystems
than any other animal.
• We rely on the ecosystem around us, just like all
living things do. We use natural resources to
meet our basic needs.
• Natural Resources: The materials and
products that are found in nature.
People and Nature: A Changing Relationship
• How have the ways people interact with the
environment changed over time??
• Gathering Food in Alberta
Buffalo Hunt → Small Farms → Feedlots
How has this affected the environment??
Needs vs. Wants
• Need: Something you need to survive
• Want: Things that make our lives more
Topic 3: Environmental Choices
• Ecological Footprint: Is a calculation of the total area
of land and water needed to supply all of the materials
and energy that you use as well as absorb all of the
waste you produce.
• What does that mean??
• Sustainability: A system where the
resources are being renewed as quickly as
they are being used. All wastes are able to
be completely absorbed.
Ways to Help the Environment
• The 3 R’s:
• Reduce: The amount of garbage you
• Reuse: Products rather than throwing
• Recycle: Find other ways to make use of
products if they cannot be reused.
Topic 4: How Organisms Interact
• There are both living and non-living parts
of an ecosystem.
• Biotic: living parts of the ecosystem
• Abiotic: non-living parts of the ecosystem
(have never been living).
The Roles of Organisms in an
• Niche: The role of an organism in its
• To determine an organism’s niche, you
must look at what it eats, where it lives,
and how it interacts with other organisms
in its ecosystem.
Types of Niches…
• Producers: make food for themselves
using the sun’s energy through a process
• Producers make life possible for all other
organisms on Earth.
• Consumers: Consumers eat the food
made by producers. Consumers can eat
producers or other consumers.
• Herbivores: Eat producers only and fill the plant-eating
niche. E.g. cows, deer, horses…
Carnivores: Eat other consumers and fill the meateating niche. E.g. wolves, coyotes, sharks…
Predators: Kill and eat other animals (cougar)
Prey: Get killed an eaten by predators (mouse)
• Omnivores: Eat both producers and consumers. E.g.
raccoons, skunks and humans
• Food Chain: is a model that shows how the energy
stored in food is passed from organism to organism.
• Food Webs: Are more complex than food chains. They
show all of the relationships between predator and prey
in an ecosystem. (They are a combination of several
Pyramid of Numbers
• Food Chains and Food Webs show how food energy moves
throughout a system but not how many organisms it involves. To
solve this, scientists invented the pyramid of numbers.
• Biomass: The total mass of all the organisms in an ecosystem
The Order of Consumers
• There are Primary, Secondary and Tertiary
The Clean-up Squad
• Scavengers: Are organisms that feed on dead or
decaying plant and animal matter.
• Decomposers: Don’t actually eat dead material, instead
they grow on or in dead material, absorbing some
nutrients into their own cells.
Topic 5: Cycles in the Environment
• The Carbon Cycle
The Water Cycle
Parts of the Water Cycle
• Evaporation: is the process in which a liquid changes
into water vapor.
Transpiration: is the process in which water that is
taken in through plants roots evaporates from the plant’s
leaves, stems and flowers
Condensation: is the process in which water vapor
changes into liquid.
Precipitation: is the process in which liquid water
forms from condensation inside clouds and falls as rain,
sleet, snow and hail.
Ground Water: is water in the soil. Plant roots can
grow down to reach ground water.
Run-off: Is water that runs off the ground into lakes,
rivers or streams.
Pollution in the Environment
• Pollution: occurs when a substance is added to
the environment at such a fast rate that it
cannot be broken down, stored or recycled in
the air, land or water in a non-damaging form.
• Acid Rain: occurs when pollutants containing
sulfur and nitrogen are found in high levels in
Movement of Pollution
• Chemicals can take a very long time to breakdown
causing a great deal of damage to plants and animals.
• Bioaccumulation: When pollutants move from level to
level in the food chain.
Topic 6: Succession and Change in
• Have you ever noticed grasses or plant growing in
vacant lot near your home? How does this process
Succession: the gradual process by which some species
replace others in an ecosystem.
Primary Succession: The gradual growth of organisms
in an area that was bare, such as rock.
E.g. Ferns and mosses growing on rocks
• Secondary Succession: The gradual growth of
organisms in an area that previously had a number of
organisms. E.g. A burnt forest area
• Biological Control: Controlling pests using their natural
Introduced Species: When exotic species are
introduced into an environment.
They often have no natural enemies and survive and
reproduce better than naturally occurring species. They
can take over an ecosystem.
E.g. Zebra mussel, Purple Loosestrife, Scotch Broom
Extinction: When a species no longer exists.
Topic 7: Environmental Monitoring
• Ecosystem Monitoring (also called Environmental
Monitoring): Is a way to check the condition of an
ecosystem by comparing the results of investigations
done at different times.
Physical Monitoring: Uses satellites to track changes
in landscape over time.
Environmental Monitoring: Tracks changes in
climate, temperature and weather patterns.
Chemical Monitoring: Assesses air, soil and water
Biological Monitoring: Tracks changes in organisms
and populations of organisms over time.
• Indicator Species: A species that is sensitive to
environmental change and is the first to be affected;
they help to monitor the overall health of our
• What would be some good indicator species??
• Baseline Data: A starting point of data that
allows scientists to go back and see if changes
Permanent Plots: Study areas that scientists
always return to.
• A report that outlines how an activity will affect
the environment is called an environmental