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Chapter 3
The Biosphere
Section 3-1: What is Ecology?
Ecology - Study of interactions among
organisms, between organisms, and their
surroundings.
The environment contains two factors:
1. Biotic Factors: all of the living things
2. Abiotic Factors: all of the nonliving
items
Section 3-1: What is Ecology?
What is the biosphere?
1. Part of earth where all life exists
2. It’s range is 11 km(6.83 mi) below the
surface ocean to 8 km(4.97 mi) above
the surface of the ocean.
Section 3-1: What is Ecology?
What are the levels of organization?
1. Species- group of organisms that can breed & produce
fertile offspring
2. Population - groups of organisms of same species
living in same area
3. Community - groups of different populations living in
same area
4. Ecosystem - all organisms that live in same area along
with environment
5. Biome - group of ecosystems with same climate &
similar dominant communities
6. Biosphere - highest level of organization; where all life
exists
Section 3-1: What is Ecology?
What are the methods used to study ecology?
1. Observing
2. Experimenting
A. Setting up an artificial environment in the
lab
B. Conducted within the natural environment
3. Modeling
A. Often based on mathematical formulas
based on data collection.
B. Models are used to make predictions
Section 3-2: Producers & Consumers
What are primary producers/autotrophs?
Organisms that make their own food from
sun/inorganic chemicals
They produce their food in two possible ways:
1. Photosynthesis: Use energy from the sun to make
organic chemicals for energy; (i.e. plants;
photosynthetic bacteria; plantlike protists;
cyanobacteria)
6CO2 + 6H2O → C6H12O6 + 6O2
2. Chemosynthesis: Capture energy from source other
than sunlight; use energy within chemical bonds of
inorganic compounds like CO2 & H2S from volcanic
vents to make organic molecules ; (example: sulfur
bacteria)
Section 3-2: Producers & Consumers
What are consumers/heterotrophs?
Organisms that can’t make their own food;
they have to eat other organism for
food/energy.
There are five types of consumers:
1. Herbivores – only eat plants
2. Carnivores – eat animals/meat
3. Omnivores – eat both plants & animals
4. Decomposers – break down dead/organic
matter; recycle nutrients (bacteria, fungus)
5. Detritivores - eat decaying stuff (worms)
Section 3-3: Energy Flow
How does energy flow in an ecosystem?
It flows in one direction, from the sun to
producers, and then to the consumers and
decomposers.
What is a food chain?
A simple series of who eats who.
Section 3-3: Energy Flow
What is a food web?
A complex interaction of all of the food
chains in an ecosystem.
Section 3-3: Energy Flow
What is a trophic level?
1. One step in the food
chain or the food web.
2. Producers always
occupy the first trophic
level.
3. Consumers occupy
every level after the
first.
4. Primary consumers
are always herbivores.
Section 3-3: Energy Flow
What is an ecological pyramid?
It is a model to show the amount of energy or
matter in each trophic level.
There are three types of ecological pyramids:
• Energy Pyramid
• Biomass Pyramid
• Pyramid of Numbers
The pyramid shape implies that there is less
at each successive level.
Section 3-3: Energy Flow
What is an energy pyramid?
1. Shows how much energy is available at each trophic
level.
2. 90% of the energy is used by the metabolism of the
organisms in that trophic level.
3. 10% is passed on to the next trophic level.
4. Each level has less and less energy available.
Section 3-3: Energy Flow
What is a biomass pyramid?
1. Shows how much food is available at
each trophic level.
2. There is less food available at each
higher level.
3. Measured in g/m2
Section 3-3: Energy Flow
What is a pyramid of
numbers?
1. Shows the number of
individuals at each
trophic level.
2. Because there is less
energy at each level,
there will be less
individuals able to
survive.
Section 3-4: Cycles of Matter
Key idea: Matter is recycled within an ecosystem &
between different ecosystems.
Recycling in the biosphere is done through the
biogeochemical cycles.
Types of biogeochemical cycles:
1. Water cycle
2. Nutrient Cycles:
A. Carbon Cycle
B. Nitrogen Cycle
C. Phosphorus Cycle
Section 3-4: Cycles of Matter
Water Cycle
Condensation
Precipitation
Evaporation
Transpiration
Runoff
Seepage
Root
Uptake
Section 3-4: Cycles of Matter
CO2 in the air
Carbon Cycle
CO2 in ocean
Section 3-4: Cycles of Matter
N2 in air
Nitrogen
Cycle
NH3
Nitrogen Fixation –
some bacteria turn N2
into the useable forms
of NO3- & NO2-.
NO3- &
NO2-
Denitrification – some bacteria convert nitrates into N2.
Section 3-4: Cycles of Matter
Phosphorus Cycle:
1. Phosphorus is
needed by living
things to form
DNA/RNA.
2. Phosphorus DOES
NOT enter the
atmosphere like C,
O, & N.
Section 3-4: Cycles of Matter
What is primary productivity?
The rate at which producers create organic matter.
What controls primary productivity?
Availability of nutrients. This is why fertilizer is
added by farmers to their fields.
What is a limiting nutrient?
A single nutrient that is scarce or slowly cycled
through the ecosystem. For most land
ecosystems, the limiting nutrient is nitrogen (N
is required for protein production).
Section 3-4: Cycles of Matter
What is an algal bloom?
1. Occurs when an
aquatic ecosystem
receives a large input
of its limiting nutrient
(phosphorus).
2. The rapid growth of
algae can disrupt the
balance of the
ecosystem. Excess
phosphorus from lawn
fertilizer can cause this.