Chapter 2 –
Principles of
Ecology
2.3 Cycling of Matter
Vocabulary List
matter
nutrient
biogeochemical cycle
nitrogen fixation
denitrification
To other organisms, this animal was a source of energy. How
might animals have used it to survive?
How might plants have used it to survive?
How might this animal’s matter continue to cycle even after its nutrients
have been consumed by predators or absorbed by the surrounding
environment?
Cycles in the BIOSPHERE
Matter provides the nutrients needed for organisms to function
• Matter is:
• Everything that takes up space and volume
• Not created or destroyed = the law of the conservation of mass
• Cycled through the biosphere.
Cycles in the BIOSPHERE
Matter provides the nutrients needed for organisms to function
• Nutrients are:
• Chemical substances that an organism needs to perform life
processes.
• Obtained by organisms from its environment.
• (along with water) the building blocks of all organisms
• include carbon, nitrogen, and phosphorus
How do nutrients cycle through the biosphere?
Nutrients cycle through the biosphere through organisms.
1.
Producers begin the cycle Plants (in most of the ecosystems) obtain nutrients from
air, water, and soil.
Plants convert the nutrients into organic compounds that
they use
How do nutrients cycle through the biosphere?
Nutrients cycle through the biosphere through
organisms.
2. When a consumer eats a producer, the nutrients in the producer pass to
the consumer. For example, the nutrients in green grass pass to the cow
that eats the grass.
How do nutrients cycle through the biosphere?
Nutrients cycle through the biosphere through
organisms.
3. The cycle continues until the last consumer dies.
How do nutrients cycle through the biosphere?
Nutrients cycle through the biosphere through
organisms.
4. Detritivores return the nutrients to the cycle, and the process begins
again.
What is the biogeochemical cycle?
• A combination of biological, chemical, and geological processes
that exchange matter through the biosphere
What is the biogeochemical cycle?
• Beside biological and chemical processes, the cycle also requires
geological processes such as weathering (breaks down large
rocks into small pieces).
– Plants and other organisms obtain nutrients from these pieces.
The Water Cycle
• Liquid water changes into water vapor (a gas) and enters the
atmosphere = EVAPORATION
The Water Cycle
• As water vapor rises, it begins to cool and condense in the
atmosphere, forming clouds
The Water Cycle
• When the droplets become large and heavy, they fall from the
clouds as precipitation (rain, hail, sleet, or snow)
Chapter Principles of Ecology
The Carbon and Oxygen Cycles
Why are carbon and oxygen important to
organisms?
 Living organisms are composed of molecules that contain carbon. (organic
molecules)
 Living things also need oxygen for many life processes
 Carbon and oxygen make up molecules needed for life, (carbon dioxide,
sugars, fats, proteins, DNA etc…).
The Carbon and Oxygen Cycles
• Producers change carbon
dioxide into carbohydrates
and release oxygen into
the air 
PHOTOSYNTHESIS
• The carbohydrates (fats,
sugars etc…) are a source
of energy for all organisms
in a food web.
The Carbon and Oxygen Cycles
• Autotrophs and
Heterotrophs release
carbon dioxide into the air
during CELLULAR
RESPIRATION.
The Carbon and Oxygen Cycles
• Carbon is also part of a cycle that could take millions of years to
complete
– conversion into fossil fuels such as gas, peat, or coal.
– Carbon is released into the atmosphere in the form of carbon dioxide
when fossil fuels are burned.
Chapter Principles of Ecology
The Nitrogen Cycle
• Organisms need nitrogen to
produce proteins, however,
most organisms cannot use
nitrogen directly from the
air.
• Nitrogen gas is captured
from the air by a species of
bacteria that live in water,
the soil, or grow on the roots
of some plants.
• NITROGEN FIXATION is
the process of capturing and
changing nitrogen into a
form that plants can use
How Does Nitrogen Enter Food Webs?
• Nitrogen enters the food web through plants.
• Consumers get nitrogen by eating producers or other animals that contain
nitrogen.
• At each step in the food web, organisms reuse nitrogen to make proteins.
What Is DENITRIFICATION?
• Nitrogen returns to the soil when
animals urinate and when
organisms die and decay.
– When organisms die,
decomposers break down
matter in the organisms into a
nitrogen compound called
ammonia (NH3)
– Ammonia is changed by
bacteria in the soil into
nitrogen compounds that can
be used by plants.
– Some bacteria in the soil
change nitrogen compounds
into nitrogen gas in a process
called DENITRIFICATION
(release of nitrogen gas (N2)
into the atmosphere)
What Is DENITRIFICATION?
• Nitrogen returns to the soil when
animals urinate and when
organisms die and decay.
– When organisms die,
decomposers break down
matter in the organisms into a
nitrogen compound called
ammonia (NH3)
– Ammonia is changed by
bacteria in the soil into
nitrogen compounds that can
be used by plants.
– Some bacteria in the soil
change nitrogen compounds
into nitrogen gas in a process
called DENITRIFICATION
(release of nitrogen gas (N2)
into the atmosphere)
Chapter Principles of Ecology
The Phosphorus Cycles
(Long Term and Short Term)
• Organisms must have phosphorus to grow and develop (bones,
teeth, DNA, RNA…)
The Phosphorus Cycles
• In the short-term cycle:
– Phosphorus is cycled from the soil to producers to consumers.
– Phosphorus returns to the soil when organisms die or produce waste
products
The Phosphorus Cycles
• In the long-term cycle:
– phosphorus is added to soil from weathering or erosion of rocks that
contain phosphorus.
– Weathering and erosion are long processes. They slowly add phosphorus to
the soil.
The Phosphorus Cycles
(Long Term and Short Term)
• Phosphorus does not dissolve in water, and only small amounts
are present in soil.
• The growth of producers is limited by the amount of phosphorus
available to them.
Chapter Principles of Ecology
CLASSWORK/HOMEWORK
 2.3 Reading Notes
 2.3 Study Guide
 BIOLAB: Field investigation: explore habitat size and
species diversity
 Virtual lab?
 Chapter 2 TEST – Monday , April 28
2.1 Study Notes
2.1 Study Guide
2.2 Study Notes
2.2 Study Guide
2.3 Study Notes
2.3 Study Guide