Name:_____________________________________Pd:_________
Biogeochemical Cycles Webquest
Directions: Login to http://www.windows2universe.org/earth/Life/biogeochem.html to read “Biogeochemical
Cycles” and complete the guided notes below.
Biogeochemical Cycles
There are a few types of atoms that can be a part of a plant one day, an ____________________ the next day, and
then travel downstream as a part of a river’s _________________ the following day. These atoms can be a part of
both living things like plants and animals, as well as non-living things like water, air, and even ____________.
The same atoms are ____________________ over and over in different parts of the Earth. This type of cycle of
atoms between _____________________ and ___________________________ things is known as a
____________________________________ cycle.
All of the atoms that are building blocks of living things are a part of biogeochemical cycles. The most common
of these are __________________ and ________________________.
Tiny atoms of carbon and nitrogen have no legs to walk, no bicycles, cars, or airplanes. Yet they can
__________________ around the world as a part of biogeochemical cycles. So, how do these little things move
around the planet? Here’s an example: An atom of carbon is absorbed from the air into the
________________water where it is used by little floating ______________________ doing photosynthesis to get
the nutrition they need. There is the possibility that this little carbon atom becomes part of the plankton’s
skeleton, or a part of the skeleton of the larger animal that eats it, and then part of a ________________________
rock when the living things die and only bones are left behind. Carbon that is a part of rocks and fossil fuels like
oil, coal, and natural gas may be held away from the rest of the carbon cycle for a long time. These long-term
storage places are called “_____________”. When fossil fuels are burned, carbon that had been underground is
sent into the air as carbon dioxide, a _______________________ ___________.
Recently, people have been causing these biogeochemical cycles to change . When we cut down
_________________, make more factories, and drive more _____________ that burn fossil fuels, the way that
carbon and nitrogen move around the Earth changes. These changes add more greenhouse gases in our
______________________ and this causes more _______________________ _____________________..
Now click on “The Carbon Cycle” link in the middle of the Biogeochemical Cycles page and continue
The Carbon Cycle: Carbon is an_____________________. It is part of oceans, air, rocks, soil and all
____________ ______________. Carbon doesn’t stay in one place. It is always on the move!
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Carbon moves from the atmosphere to _______________.
In the atmosphere, carbon is attached to oxygen in a gas called carbon dioxide (CO2). With the help of
the Sun, through the process of _________________________, carbon dioxide is pulled from the air to
make plant ________________ from carbon.
Carbon moves from plants to animals.
Through _____________ _______________, the carbon that is in plants moves to the animals that eat
them. Animals that eat other animals get the carbon from their food too.
Carbon moves from plants and animals to the__________________.
When plants and animals die, their bodies, wood and leaves _______________ bringing the carbon into
the ground. Some become buried miles underground and will become _______________ ____________ in
millions and millions of ____________.
Carbon moves from living things to the ______________________.
Each time you _________________, you are releasing carbon dioxide _____________(CO2) into the
atmosphere. Animals and plants get rid of carbon dioxide gas through a process called
___________________.
Carbon moves from fossil fuels to the atmosphere when fuels are __________________.
When humans burn fossil fuels to power ____________________, power plants, cars and trucks, most of
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the carbon quickly enters the _____________________________ as carbon dioxide gas. Each year, five and
a half billion tons of carbon is released by burning ___________________ _______________. That’s the
weight of 100 million adult African elephants! Of the huge amount of carbon that is released from fuels,
3.3 billion tons enters the atmosphere and most of the rest becomes dissolved in _____________________.
Carbon moves from the atmosphere to the ____________________.
The oceans, and other bodies of water, __________________ up some carbon from the atmosphere.
Carbon dioxide is a ___________________ _______________ and traps _______________ in the atmosphere.
Without it and other greenhouse gases, Earth would be a frozen world. But humans have burned so much fuel
that there is about ____________more carbon dioxide in the air today than there was about 150 years ago. The
atmosphere has not held this much carbon for at least 420,000 years according to data from ice cores. More
greenhouse gases such as carbon dioxide in our atmosphere are causing our planet to become _________.
Carbon moves through our planet over longer time scales as well. For example, over millions of years
______________________ of rocks on land can add carbon to surface water which eventually runs off to the
ocean. Over long time scales, carbon is __________________ from seawater when the shells and bones of marine
animals and plankton collect on the sea floor. These shells and bones are made of ______________________,
which contains carbon. When they are deposited on the sea floor, carbon is _____________________ from the
rest of the carbon cycle for some amount of time. The amount of limestone deposited in the ocean depends
somewhat on the amount of warm, tropical, shallow oceans on the planet because this is where prolific
limestone-producing organisms such as ___________________ live. The carbon can be released back to the
atmosphere if the limestone melts or is metamorphosed in a _________________________ zone.
Now go back to the Biogeochemical Cycles page and click on “The Nitrogen Cycle” link in the middle of
the page and continue
The Nitrogen Cycle: Nitrogen is an ________________. It is found in living things like plants and
_________________. It is also an important part of non-living things like the air above and the ____________
below. Atoms of nitrogen don't just stay in one place. They move slowly between living things, _____________
things, the air, soil and _____________. These movements are called the _____________________
_______________.
Most of the nitrogen on Earth is in the _______________________. Approximately ___________% of the
molecules in Earth's atmosphere are made of two nitrogen atoms bonded together (N2). All plants and animals
need nitrogen to make ____________________ acids, proteins and _________________, but the nitrogen in the
atmosphere is not in a form that they can use. The molecules of nitrogen in the atmosphere can become usable
for living things when they are broken apart during lightning strikes or fires, by certain types of
_____________________, or by bacteria associated with bean _________________.
Most plants get the nitrogen they need to grow from the _______________ or water in which they live. Animals
get the nitrogen they need by ________________ plants or other _________________ that contain nitrogen.
When organisms die, their bodies _________________________ bringing the nitrogen into soil on land or into
ocean water. ______________________ alter the nitrogen into a form that plants are able to use. Other types of
bacteria are able to change nitrogen dissolved in waterways into a form that allows it to return to the
______________________________.
Certain actions of ____________________ are causing changes to the nitrogen cycle and the amount of nitrogen
that is stored in the land, water, air, and _____________________. The use of nitrogen-rich ___________________
can add too much nitrogen in nearby waterways as the fertilizer washes into streams and ponds. The waste
associated with livestock farming also adds large amounts of nitrogen into soil and water. The increased nitrate
levels cause plants to grow _____________________ until they use up the supply and die. The number of planteating animals will _______________________ when the plant supply increases and then the animals are left
without any food when the plants _____________..
The Carbon Cycle
The Nitrogen Cycle
The Carbon Cycle
The Nitrogen Cycle
The Carbon Cycle
The Nitrogen Cycle