Ecosystems
8.11 The student knows that
interdependence occurs among living
systems and the environment and that
human activities can affect these systems.
The student is expected to:
(A) Describe producer/consumer,
predator/prey, and parasite/host
relationships as they occur in food webs
within marine, freshwater, and terrestrial
ecosystems;
(B) Investigate how organisms and
populations in an ecosystem depend on and
may compete for biotic and abiotic factors
such as quantity of light, water, range of
temperatures, or soil composition
What is an ecosystem?
• Click here to find out!
• There are several different types of
ecosystems including: marine, freshwater,
and terrestrial.
Quick Review:What are Biotic &
Abiotic Factors?
• Click here to find out!
Words to know…
• Species- group of organisms that can mate
and produce offspring that in turn can
produce more offspring
• Population- all of the organisms of the same
species that live in the same place at the
same time
• Community- areas where populations share
the environment with other populations
• Ecosystem- all of the living and non-living
factors in an area
Factors that Affect Populations
• Limiting factors- factors such as food, water, and
living space; factors that limit how many
organisms can live in one environment
• There is only so much food and water available in
an ecosystem.
• Plants and other organisms that make their own
food need light for photosynthesis. If light is
limited, their growth is limited.
• Organisms need room to live, obtain resources,
and reproduce. This is called a habitat.
• A niche is a role that an organism plays in a
habitat.
Relationships Between
Populations
• Competition occurs when more than one
individual or population tries to use the same
limited resources. There is not enough food,
water, and space for all organisms, so only those
who get the resources they need will survive.
• Predation is a type of feeding relationship where
one animal (predator) eats another animal (prey).
• Symbiosis is a close relationship between two
species including mutualism (both benefit),
commensalism (one benefits, the other is not
harmed or helped), and parasitism (one is
harmed, one is helped).
COMPETITION
• Organisms compete for resources
• Competition can be intraspecific
(competing with organisms of the same
species)
• Competition can be interspecific
(competing with organisms of different
species)
Click here for Competition,
Predation, and Symbiosis Video
What do organisms compete for?
Plants and animals compete for the
following biotic and biotic factors:
• Quantity of light
• Water
• Range of temperatures
• Soil composition
They compete because there is a limited
number of resources.
PREDATION
• Click here to see a video!
• A predator is an animal that kills or
hunts other animals for food.
• What is an example of a predator in
a marine ecosystem? Freshwater?
Terrestrial?
• Prey is an animal that is eaten by
another animal.
• Give an example of prey in a marine
ecosystem. Freshwater?
SYMBIOSIS
• Symbiosis is a close relationship between
two species. There are three types:
• Mutualism- both species benefit
• Click here for a video about mutualism.
• Commensalism- one species benefits
and the other is neither helped nor harmed
• Click here for a video on commensalism.
• Parasitism- one species benefits and the
other is harmed
• Click here for a video about parasites.
Parasite vs. host…what’s the
difference?
• A parasite takes nourishment from and
harms the host.
• A host is the organism infected with or fed
upon by a parasitic organism.
• Give an example of a parasite and host
from a marine, freshwater, and terrestrial
environment.