ECOLOGY is the study of interactions that
The BIOSPHERE is the portion of Earth that
supports living things
◦ Extends from highest mountain to the bottom of
the oceans Air
Land
The nonliving parts of an organism’s
environment are called ABIOTIC FACTORS
◦ Air currents, Temperature, Water, Sunlight, Soil
All living organisms that inhabit an
environment are called BIOTIC FACTORS
1. Organism – a single individual
2. Population – a group of the same species
in the same place at the same time
3. Community – all living things; interacting
populations
Terrestrial – located on land
◦ Forest, Desert, Rotting Log, Mountain
Aquatic – Located in fresh or salt water
A HABITAT is the place where an organism
lives its life
When several species share the same habitat
and use the same resources, COMPETITION may result
Using different resources leads to reduced
A NICHE is an organism’s role in its
environment; how it obtains energy
◦ What it eats, how it eats, where it lives, etc.
Most of the time different species occupy
different niches (reduced competition)
When two species have the exact same niche,
Lions kill prey and eat meat Monkeys climb trees and eat fruits and insects
PREDATORS hunt and eat other organisms
The animals predators eat are called PREY
PREDATOR
SYMBIOSIS is a close and permanent
relationship between organisms of different species
SYM = together; BIOSIS = living
3 types of symbiosis:
◦ Mutualism
A symbiotic relationship between two species
where both species BENEFIT (+,+)
◦ E.g. Bees and Flowers. Bees benefit by using nectar
A symbiotic relationship between two species
where one species benefits and the other is neither harmed nor benefited (+,0)
◦ E.g. The remora, a small sucker fish, attaches to a
A symbiotic relationship where one species
benefits and the other species is HARMED;
◦ The organism that is being harmed is called the
The ultimate source of energy for life is the
SUN
Plants use the sun’s energy to manufacture
An organism that can make its own food is
called an AUTOTROPH
Autotrophs are also called PRODUCERS
because they provide the entire food chain with energy
Plants and algae are the most common type
An organism that cannot make its own food
is called a HETEROTROPH
Heterotrophs obtain energy by eating other
organisms
◦ Heterotrophs are also known as CONSUMERS
An HERBIVORE is a heterotroph that feeds
only on PLANTS
A CARNIVORE is a heterotroph that feeds only
on other heterotrophs (meat, insects, etc)
An OMNIVORE is a heterotroph that feeds on
BOTH plants and animals
A SCAVENGER is a heterotroph that does not
kill for food but eats already dead animals
DECOMPOSERS break down and release
nutrients from dead organisms (recycle)
A FOOD CHAIN is a simple model that shows
how matter and energy moves through an ecosystem
producers consumers decomposers
◦ Arrows on a food chain show the direction ENERGY
Each step in a food chain is called a TROPHIC
LEVEL
Trophic levels include:
◦ Producers – autotrophs that produce their own food ◦ Primary Consumers – heterotrophs that eat
autotrophs
◦ Secondary Consumers – heterotrophs that eat
primary consumers
◦ Tertiary Consumers – heterotrophs that eat
Most of the time food chains are too simple
and don’t show all of the feeding relationships in an ecosystem
A FOOD WEB is a complex model of
As energy moves up the food chain, 90% of it is lost as HEAT
Only 10% of energy moves up to the next level
◦ The 90% that is lost is used up by the organism for metabolism and movement; only 10% is stored in its tissues
Biomass – The total weight of living organisms at each trophic level
As matter flows up a food chain, toxins in the
bodies of organisms are accumulated at each trophic level.
Top predators receive the highest doses of
Matter and nutrients must be recycled in all
ecosystems; matter is not unlimited like energy from the sun
Nutrient cycles:
All life depends on water. Water moves around the Earth in a cycle
EVAPORATION: liquid water changes into water vapor (liquid gas)
CONDENSATION: water vapor changes to liquid water (gas liquid)
PRECIPITATION: water falls from the atmosphere back to Earth (rain, snow, etc.)
RUNOFF: gravity causes all water to eventually flow back to oceans or lakes
TRANSPIRATION: plants lose water vapor through their leaves
All life is based on Carbon molecules
◦ Carbon atoms form the backbone for proteins,
carbohydrates, fats, and nucleic acids
Autotrophs convert CARBON DIOXIDE (CO2)
and water into sugars through the process of photosynthesis
Plants and animals break down the sugars
A large amount of CO2 dissolves in and out of the oceans. Too much CO2 = ocean acidification.
Decomposers break down and return the
carbon of dead plants and animals back to the atmosphere.
When plants and animals die and are quickly
buried, over millions of years, the carbon in their bodies can be converted into FOSSIL FUELS
When fossil fuels are burned CO2 is released
78% of the air is Nitrogen (N2)
Plants cannot use nitrogen in this form
◦ N≡N is a triple bond and is too difficult to break apart
Bacteria in the roots of plants “fix”
atmospheric nitrogen by turning it into a usable form for plants
◦ N2 nitrates (NO2, NO3) or ammonia (NH4) Animals get nitrogen by eating plants
Animals return nitrogen to the soil through
Industrial man-made fertilizers also provide
nitrogen to plants in a usable form
Lightning can also fix atmospheric nitrogen