Ecosystem

sciencescience
RevisionRevision

Grade 7

Ecosystems

An ecosystem is all the

living and nonliving

components in a particular

area.

The components of the

ecosystem interact. When

two things interact, they

affect one another.

Parts of an Ecosystem

1- Abiotic

The nonliving parts of an ecosystem

as abiotic factors.

2- Biotic

Plants, animals, fish,

insects, etc

(air, water, rocks, soil, sunlight, and

temperature)

What is a community?
All the organisms living together

in an ecosystem make up a

community. The community’s

members depend on one another

to fill needs.

Water, temperature, and

sunlight determine the number

and types of organisms that

can live in an ecosystem.

The rain forest of Colombia has
many types of organisms. The
desert of Libya has only a few

types of organisms.

The living parts of an

ecosystem as

Ecosystems

Ecosystem Size

An aquarium is a small

ecosystem. The aquarium

walls are its boundary.

Ecosystems can be any size.

They can be as small as a drop

of water or larger than an

entire forest.

In fact, the entire Earth is an

ecosystem.

There are ecosystems anywhere that living

things are found, including the highest

mountain, the deepest ocean, the hottest

desert, or the coldest Arctic place.

Organisms Within

Ecosystems

Organisms need energy to carry on life

processes, such as moving and

reproducing. They need matter to
grow, to reproduce, and to repair

damaged body parts.

What is a producer?

An organism that makes its

own food using nonfood

matter and energy from the

sun.

When other organisms eat a
producer, they take in this
matter and energy. Without

producers, matter and energy
would not be available to other

organisms in an ecosystem.

What is a consumer?

Organisms that cannot
produce their own food

must eat other organisms.
They are called consumers.

What are decomposers?

Decomposers are organisms that

break down, or decompose,
other organisms’ bodies after

they die.

They also break down the wastes
that animals produce. They are
very important as they help with

cleaning the environment.

Organisms Within

Ecosystems

Microbes are organisms that are too
small to see. These include bacteria

and very small fungi. Larger

decomposers include earthworms and

flies.

Microbes

Whale - Zooplankton- phytoplankton

The largest animal in the ocean feeds on
the smallest. Zooplankton get caught in
the comb-like sheets, called baleen, that

blue whales have instead of teeth.

Zooplankton are tiny animals that
eat even smaller producers called

phytoplankton. They are weak

swimmers, so they drift along with

currents.

Food Chain

A food chain shows how
matter and energy flow
from one organites to
another.Producers always
spement the first link is a
food chain

Food Web

A food web is a set of
interconnected food

chains.

A food chain is not a good

tool for describing the

transfer, or movement, of
matter and energy in an

ecosystem. Use a food web.

Change within Ecosystem.

Changes to ecosystems
differ in how they affect

ecosystems.

Succession

Succession refers to a series of

changes in a community.

primary succession.

When plants and animals start
living on new land, the process

is called primary succession.

secondary succession.

When plants and animals return

to disturbed or damaged land, the

process is called secondary

succession.

Stable Ecosystems

Stable means steady, or

unchanging.

Organisms can survive only in

ecosystems that meet their

needs. A stable ecosystem can

meet the needs of multiple

species, or kinds of organisms.

The number of individuals of

each species in a stable

ecosystem may change a bit

over time as conditions

change slightly. But during
the changes, the ecosystem

remains stable.

Characteristics of healthy ecosystems

Threats to healthy ecosystems

adequate shelter and nesting sites
balance of decomposers, producers, and
consumers
a variety of species
adequate supply of clean air, water, and
nutrients

habitat loss due to human activities and
natural events such as forest fires
introduced species that crowd out other
species
rapidly growing human population
overfishing or overharvesting
pollution
drought

Change within Ecosystem.

In any ecosystem, organisms compete. Competition occurs when organisms in an

ecosystem need the same resources.

Competition

For example, if a new plant species is introduced into a stable ecosystem, the new

plant will compete with other plants for sunlight and water.

Matter and Energy Transfer Within

Ecosystems

Matter must enter and exit living
organisms so that they can get the

nutrients they need. The flow of

matter in ecosystems cycles.

To cycle means “to move through a

series of steps that repeat.”

The first step in the

cycle of matter
happens when

producers take in

matter from the air,

soil, and water.

Matter travels to consumers

when they eat plants or animals.

Decomposers break down dead

bodies and the wastes

organisms make. The broken-

down matter can be returned to

the soil.

Unless the energy of an organism is
recharged, the organism will not be

able to carry on life processes.

As you spread your wings and soar toward new
horizons, always remember that you have the

power to change the world with your knowledge

and passion.

With warm regards,

Mr.Samir