Bell Ringer
In nature, matter is constantly being
recycled. What would happen if matter
could not be recycled?
Write a paragraph-length answer.
Cycles of Matter
HOW IS MATTER
RECYCLED?
Cycles of Matter
 Recall from the last unit that energy
only goes in one direction – from
producer to consumer.
 Unlike energy, matter is constantly
recycled. This is because of the Law of
Conservation of Mass.
Cycles of Matter
 Think about what happens in a food
web. Producers are consumed by
primary consumers. Those animals are
eventually consumed by other animals.
 Eventually, all living organisms release
waste, and all living organisms die and
decompose. These processes release
matter back into the world.
The Water Cycle
 All living organisms
require water to
survive.
 Water is constantly
being recycled, so that
all organisms can
meet their water
requirements.
 What would happen
with no water cycle?
The Water Cycle
 Evaporation is the
process of where
liquid water becomes
water vapor.
 Condensation is the
opposite process.
Water vapor becomes
liquid water.
 Transpiration is the
process where water
evaporates from the
leaves of plants.
The Water Cycle
 The water cycle is
important because it is
the reason we have
precipitation and
freshwater.
 Ocean water evaporates,
forms clouds, and
condenses into
precipitation.
 Runoff becomes
freshwater,
groundwater or returns
to the ocean.
The Water Cycle
The Carbon Cycle
 Carbon is one of the
most important
elements in our body.
It is an important part
of our biomolecules.
 Carbon is also being
recycled, which results
in carbon being
moved from CO2 to
carbon compounds,
and back again.
The Carbon Cycle
 CO2 is released into
the atmosphere by:
Respiration
 Burning of fossil fuels
 Wildfires/Volcanic
activity

 Photosynthesis
removes CO2 from
atmosphere.
the
The Carbon Cycle
 CO2 in the atmosphere
and in the ocean is
constantly being
exchanged.
 Both photosynthesis
and respiration occur
underwater.
 Decomposing
organisms become
organic matter, and
possibly fossil fuels.
The Carbon Cycle
 People and other
animals breathe in
oxygen, and breathe out
carbon dioxide.
 As plants use carbon
dioxide for
photosynthesis, they
create carbohydrates.
 Other organisms use
carbon for other
molecules, like calcium
carbonate.
The Carbon Cycle
Exit Ticket
1.
2.
3.
4.
5.
6.
Why must matter constantly be recycled?
What do we call organisms that break down dead
matter into smaller particles?
The process of converting water vapor to liquid
water is _________.
Water evaporates from the leaves of plants in
_________.
Photosynthesis removes ________ from the
atmosphere.
Fossil fuels are formed from ________.
The Nitrogen Cycle
 The nitrogen cycle is
important because
nitrogen is the key
component in amino
acids, which make up
our proteins.
 Nitrogen is a huge part
of our planet, and takes
various forms: nitrogen
gas, ammonia, nitrites
and nitrates.
The Nitrogen Cycle
 Nitrogen gas (N2) is the
most abundant form of
nitrogen on the planet,
but very few organisms
can use it. It’s also the
most abundant gas.
 Only certain bacteria,
known as nitrogen
fixers, can use nitrogen
gas. They convert it into
ammonia (NH3).
 Nitrogen fixers are found
in the soil, and on the
roots of legumes.
The Nitrogen Cycle
 Other bacteria can
then convert the
ammonia (NH3) into
nitrites (NO2‾) and
nitrates (NO3‾).
 Nitrites and nitrates
are used by producers
to make proteins.
Consumers then get
those proteins through
consumption.
The Nitrogen Cycle
 Organisms also add
nitrogen to the soil
when they die.
Decomposers, such as
fungi, break dead
organisms down.

Remember primary
succession?
 Finally, some soil
bacteria can convert
nitrates into nitrogen gas
via denitrification.
The Nitrogen Cycle
 The nitrogen cycle is
critical for converting
nitrogen gas to usable
nitrogen compounds.
 Fixer bacteria synthesize
nitrates and nitrates,
which are absorbed by
plants.
 Humans and other
animals consume plants
and other animals to get
the nitrogen compounds.
The Nitrogen Cycle
The Phosphorus Cycle
 The phosphorus cycle
provides us with
phosphorus, a key
component of DNA
and RNA.
 It is rather
uncommon, though. It
does NOT become
airborne at any point.
The Phosphorus Cycle
 Most phosphorus in
nature is locked in
rock and soil.

This includes ocean
sediment.
 Eventually, these rocks
are broken down, and
the soil washed away.
The Phosphorus Cycle
 This phosphorus is
usually washed into
the rivers and oceans.
 However, some
phosphorus is
absorbed by plants.
Plants use this
phosphorus to make
organic molecules.
The Phosphorus Cycle
 Once again, humans
and other animals eat
the plants to get
phosphorus…
 …or they eat other
animals to get
phosphorus.
 What other cycle does
this remind you of?
The Phosphorus Cycle
Exit Ticket
1.
2.
3.
4.
5.
6.
Most nitrogen on Earth is found in the form of
____________.
Can we use pure nitrogen gas as a nutrient?
What do we call bacteria that convert nitrogen gas
to nitrites and nitrates?
___________ also add nitrogen to the soil as
they break down dead organisms.
Where is most phosphorus found in nature?
How do we obtain nitrogen and phosphorus from
the environment?