Chapter 3: The Biosphere
What is ecology?
Ecology
• Ecology – the study of interactions among
organisms and between organisms and their
environment
• Interdependence – dependence of every
form of life on other living things and
natural resources (air, water, land) in its
environment
Levels of Organization
• Biosphere – largest, portions of planet
where life exists (land, H2O, air)
– 8 km above to 11 km below
• Biome – group of ecosystems with same
climate (temp. and rainfall)
• Ecosystem – collection of all organisms in a
particular place together with the abiotic
(physical) environment.
Levels of Organization
• Community – groups of different
populations that live together in a defined
area.
• Population – groups of individuals of same
species in same area.
• Species – group of organisms so similar that
they can mate and produce fertile offspring.
Levels of Organization
Biotic and Abiotic Factors
• Biotic – living
– Plants, Animals ,Mold,
Fungi, Bacteria, Protist
• Abiotic – Non living
– Sunlight, soil, wind, water,
temperature
• Habitat – the area where an
organism lives; includes both
biotic and abiotic factors.
3.2 Energy - Autotrophs (producers)
• Can trap light energy to produce food (organic
molecules)
– Plants
– Some protists
– Some bacteria
• Photosynthesis – captures solar energy and
converts it to chemical energy
SUN
6CO2 + 6H2O
C6H12O6 + 6O2
• Chemosynthesis – Chemical energy used to produce carbohydrates
3.2 Energy - Heterotrophs (consumers)
• Can’t trap energy directly;
must acquire it from other
organisms
–
–
–
–
Herbivores – plants
Carnivores – animals
Omnivores – both
Detritivores – remains of dead
plants & animals
– Decomposers – break down
organic matter
3.3 Energy Flow in
Ecosystems
• Food Chains and Food Webs
3.3 Food Chains and Food Webs
SUN
Autotrophs
Heterotroph
1. Food Chain – energy trapped by producers
passed on when organisms eat and are eaten
2. Food Web – relationship more complex than a
chain
Trophic Levels and Ecological
Pyramids
• Trophic Levels – each step in a food chain/web
Ex: producers, then consumers
• Ecological Pyramids – shows relative amount of energy
at each level (10% rule)
• Biomass – total amount of living tissue within a trophic
level
Trophic Levels and Ecological
Pyramids
3.4 Cycles of Matter
*Recycle Matter*
Carbon Cycle
• Photosynthesis – uses CO2 from
atmosphere
– Happens in the CHLOROPLAST
• Respiration – returns CO2 to atmosphere
– Happens in the MITOCHONDRIA
Carbon Cycle
The Carbon Cycle
1. Volcanoes, respiration, fossil fuels, and
decomposition add CO2 to atmosphere.
2. Plants take CO2 and make carbohydrates
3. Plants are eaten by animals and carbohydrates
are passed through the food chain.
4. As the animal breathes and eventually dies and
decomposes CO2 is return to atmosphere.
Decomposing Fox
Water Cycle
Water Cycle
1. Water enters the atmosphere by:
•
•
Evaporation – water changes from a liquid to a
gas
Transpiration – Evaporation through leaves
2. As water rises it cools condenses into tiny
droplets that form clouds.
3. Droplets return to Earth as precipitation.
4. Water enters the rivers, ground water, ocean
or plant roots to restart cycle.
Making Clouds
Nitrogen Cycle
Nitrogen Cycle
1. Nitrogen gas makes up 78% of atmosphere
2. Nitrogen Fixation: bacteria take nitrogen gases
and turn it into ammonia, nitrite, and nitrate.
3. Plants and animals use nitrate to make amino
acids.
4. Animal dies and decomposes returning nitrates
to the soil.
5. Denitrification: other bacteria convert nitrates
into nitrogen gas.
Fertilizer Runoff
Nutrient Limitation
• Primary Productivity – the rate at which
organic molecules are created by producers
• If nutrients are in short supply, they are
called LIMITING NUTRIENTS
Ex: Nitrogen is often limiting in water; if
there is suddenly as input of N (fertilizer
runoff), organisms can grow rapidly (Algal
Bloom)
4-2 Niches and Community
Interactions
4.2 The Niche
• Niche – Where and How something lives;
its role
– Habitat is the organism’s address
– Niche is the organism’s occupation
Community Interactions
1. Competition
•
Organisms compete for
resources
Ex: Food, Mates, Shelter
•
Competitive Exclusion
Principle – no 2 organisms
occupy same niche at same
time.
2. Predation
•
One organism (predator)
captures and feeds on another
(prey).
Battle at Kruger Lake
4.2 Community Interactions
3. Symbiosis
•
Mutualism – both benefit
Ex: Flowers & insects
Egrets & Alligators
Clown Fish & Sea Anemone
•
Commensalism – one
benefits, the other is not
helped nor harmed
Ex: Barnacle & Whale
•
Parasitism – one benefits,
other is harmed
Ex: tapeworms, fleas, ticks,
lice
Keystone Species – essential to the balance of an
ecosystem, change in their population can cause a
dramatic change in the community.
Dung Beetle
Otters and
Kelp
4.3 Ecological Succession
•
Ecological Succession - change in an ecosystem
1. Primary Succession – no soil (volcanic eruption or bare
rock)
– first to appear are “pioneer species” Ex: Lichens
2. Secondary Succession – Soil Exists (wild fires, clear
cutting, plowed for farming)
3. Succession in a Marine Ecosystem – happens when a
large whale dies and sinks to the bottom
4. Climax Community – fairly stable, mature, dominant
community established after succession.
Human Impacts
Look at each of the cycles in your notes. In each
cycle there is at least one to two ways that imbalance
can occur.
• Identify the sources of imbalance and in
particular how human activities upset the cycles.
• Explain how this imbalance impacts the cycle
and potential ecological problems that could
result.
• You should identify at least one imbalance for
each cycle (water, nitrogen, and carbon)?
• Each table group will turn in one paper with your
answers.