Ch. 4 Interactions
of Life
Section 1 : Living Earth
 Biosphere:
 The part of Earth that supports life
 From the floor of the deepest sea to the
atmosphere
Ecosystems
 All the living and nonliving parts of an
environment
 Ex:
soil
+ rocks
+ water
+ plants
+ mammals
+ insects
+ amphibians
+ reptiles
+ birds
+ fish
+ air quality
ecosystem
Ecology
 The study of
interactions between
organisms and their
environment.
 Can you explain one?
 Ex: Wolves and
Yellowstone National
Park.
 Do they belong there,
or should we kill them
off?
Populations
 All the organisms in an ecosystem that
belong to the same species.
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Whitetail deer
Red Maple
Fire ants
Brook trout
Mountain Laurel bush
Community
 All the populations in an ecosystem
 All living organisms that interact and survive
together.
 Describe the community that thrives in Yellow
Creek?
 Habitat
 An area where a population or a community lives.
 Needs to provide adequate food, space/shelter,
temperature, and water
Section 2: Populations
 Population Competition
 Two or more organisms of the same species
competing for resources at the same time
 Food
 Living space/Shelter
 Water
 Oxygen or Carbon Dioxide
 Sunlight
Population Size
 Indicator of the health of a population
 Density
 The size of a population that inhabits a specific area.
 Number of individuals per square unit of area.
 12 deer per square mile
 Affected by:
 Limiting factors
 Any living or nonliving feature that restricts the population size
 Carrying Capacity
 The largest number of individuals that can inhabit an ecosystem.
 Biotic Potential
 Highest rate of reproduction under ideal conditions.
 Birth and Death rates
 Migration of organisms into and out of an area
What is the population
density of the rabbits?
100 yards2
11 rabbits / 100 yards2
 In our area the carrying capacity for
cottontail rabbits is @ 8/100 yards2.
 Answer these questions in your notes.
 Is this population healthy?
 Is this population going to crash?
 Will the all the rabbits be healthy?
Sct. 3
Interactions in Communites
 2 levels of populations within each
community.
 Producers
 Organisms (plants) that use the sun to produce
energy.
 Begin all food webs on Earth
 Consumers
 Organisms that cannot produce their own energy
 Must consume producers or other consumers for
energy
4 types of consumers
 Herbivores
 Eat plants
 Giraffes
 Carnivores
 Eat animals
 Brown Recluse Spiders
 Omnivores
 Eat plants and animals
 Bears
 Decomposers
 End all food webs on Earth.
 Decompose dead organisms
 Fly larvae
Food Webs
 What starts food webs on earth?
 What type of organism must be at the
beginning of every food web?
 What types of organisms fill in the rest of
the web?
 What type of organism must be at the
end of each strand of the food web?
Freshwater food web of
Bedford County.
Terrestrial Food Web of
Bedford County.
 Begin and end a food web of your own
with the correct steps.
 Use at least 20 producers, consumers,
and decomposers.
 Add graphics and color(if you wish.)
 Due tomorrow. 10 pts.
Relationships in
Communities
 Symbiosis
 Relationship between two species or
populations
 Mutualism
 When both species benefit
 Commensalism
 One benefits and the other is not affected
 Parasitism
 One benefits and the other is harmed
Mutualism, Commensalism,
or Parasitism?
 The clownfish lives among the forest of
tentacles of an anemone and is protected from
potential predators not immune to the sting of
the anemone.
 Commensalism
Mutualism, Commensalism,
or Parasitism?
 Burdocks
 Spines attach themselves to passing
animals and humans.
 These organisms transfer the
burdocks, which contain the plants
seeds, to other areas and deposit
them.
 The burdock plant benefits and the
other organisms are neither
benefited or harmed, just a little
annoyed.
 Commensalism
Mutualism, Commensalism,
or Parasitism?
 Berries + English Starling + Pooh =
 Mutualism
 Berry bushes gain seed dispersal.
 Starlings gain food.
Mutualism, Commensalism,
or Parasitism?
 Lake Trout from Lake Erie with Lamprey
attached.
 Parasitism
Niche
 An organisms role in the ecosystem
 Ex:
 Oak Tree


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Remove CO2
Produce O2
Provide habitat
Provide shade
Provide food
Store nutrients to return to the soil
Prevent erosion from water and wind
Questions….use notes.
 Describe the niche in our ecosystem for:
 Whitetail deer.
 Turkey Buzzard.
 Raspberry bush
 Explain an example of each relationship
in our ecosystem and why it is….
 Mutualism
 Commensalism.
 Parasitism.