Good Science Victorian Curriculum Year 7

BIOLOGICAL SCIENCES
3.3
COMMUNITY
INTERACTIONS
IN AN
ECOSYSTEM
LEARNING INTENTION
At the end of this lesson I will
be able to describe some key
community interactions that
exist within an ecosystem.
KEY TERMS
predator
a consumer that kills and feeds
on another animal
prey
an organism that is hunted
and killed by another for food
symbiosis
a relationship between two or
more organisms that live closely
together
LITERACY LINK
LISTENING
Read section 1 out loud to
a partner, then ask them to
summarise what you read. Repeat
for section 2, swapping roles.
NUMERACY LINK
MEASUREMENT
This thermometer was left
and allowed to stabilise in
an ecosystem. What is the
temperature of the ecosystem?
If possible, use a thermometer to
measure the temperature of an
ecosystem outside.
1
2
There’s more to an ecosystem than just who eats whom.
Food chains and food webs are complex and easily affected
by internal and external factors. Interactions between
organisms can be helpful or harmful, as they are often in
competition for resources and not all relationships in an
ecosystem are healthy ones!
Organisms compete for resources
Competition often occurs when organisms share the same limited
resource, such as food, in the same ecosystem.
Consumers compete with each other for the same food. This can
occur between different species or members of the same species.
Depending on the amount of food available, organisms may be harmed,
may starve or may have to find a new food source.
Producers also compete for resources, but not food. Plants compete
for space, light, water and nutrients – the things they need to produce
energy. Some plants will grow and survive, while others will die.
What are two resources that plants compete for in an
ecosystem?
Predators and parasites get nutrients
from other organisms
Predators are consumers that kill and feed on another animal,
their prey. Predators in a food web include omnivores and carnivores,
both of which eat meat. Carnivores are always predators within a
food web, but omnivores are predators in some food chains and prey
in others. Predators benefit by gaining energy and nutrients from
their prey.
Parasites are organisms that live
in or on another organism,
the host. Parasites harm the host,
but they don’t kill it. Examples
of parasites include hookworms,
which live in the intestines of their
human hosts, feeding on nutrients
from digested food.
What is the main difference
between predators and
parasites?
40 GOOD SCIENCE VICTORIAN CURRICULUM 7