Bio A. Name _______________________________Date____________________________
Lab Activity 2. UNDERSTANDING BIOGEOCHEMICAL CYCLING AND ITS LINK TO LIVING THINGS
http://www.colorado.edu/GeolSci/courses/GEOL1070/chap04/chapter4.html
Biogeochemical cycles show the cycling (or movement) of matter through a system. Nature is very
efficient at recycling. In fact Nature has used the same atoms to build living and non-living things since
the beginning of time. So, if nature wants to build something new, it must recycle the atoms from
something else. What does this mean? Some of the atoms in YOU may have been atoms in dinosaurs,
bacteria, fungi, or even mountains.
Different atoms are recycled in different ways. But all atoms in living things move in and out of living
things into the “earth system”. When we talk about the earth, we divide the earth “system” into four
components or parts. These components are the hydrosphere, atmosphere, lithosphere, and biosphere.
Define what each of these terms means:
Hydrosphere
Lithosphere
Atmosphere
Biosphere
The term “matter” basically refers to elements (Carbon or C) or molecules (hydrogen or H2, oxygen or
O2, nitrogen or N2, phosphorus) or compounds (like CO2 or carbon dioxide, H2O or water, NO3 and NO3
(nitrites and nitrites)). So based on my descriptions and the elements and compounds I have described,
what makes elements, molecules and compounds different from each other?
Element
Molecule
Compound
So, the movement of matter between the parts of the earth system is referred to as a biogeochemical
cycle (and we actually separate it into different cycles). The elements we are most interested in are the
“big six” elements found in macronutrients (proteins, lipids, carbohydrates, and nucleic acids). We will
learn more about the macronutrients later.
These are Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus and Sulfur. Use the first letter of each of
these elements (which is also the element symbol) to form an acronym (be sure to put them in the same
order that they are listed:
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Biogeochemical cycles are part of larger cycles that describe the functioning of the whole earth (not just
the surface of the earth, where most living things are found). The geologic cycle includes the tectonic
cycle, the rock cycle, the hydrologic cycle and biogeochemical cycles. This activity will focus on the
hydrologic (or water) cycle and the biogeochemical cycles. We will then discuss the rock cycle. In the
evolution section of our course we will discuss tectonic plates. Biogeochemical is a “big word”. So…let’s
break it down and create a definition in your own words:
Bio-
Geo-
Chemical-
Cycles
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Bio A. Name _______________________________Date____________________________
Activity Directions:
In this activity you will be given a verbal description of how a particular atom or molecule is recycled by
nature. Your job is to sketch and color the written description to create a picture of the cycle. Many of
us prefer learning visually, rather than reading, but at the end of this exercise you will have the same
information presented in two different ways. When finished you can choose which is easiest for YOU to
study!
Requirements for drawings:
1.
I recommend a rough draft. I can make suggestions on your rough drafts, but once final drafts
are completed, no corrections can be made.
2. Final drafts should be completed on the attached sheets beneath the description of the cycle. If
you choose to draw on a computer (you MAY NOT copy and paste a diagram you find online),
you must print these pages beneath the description or past your diagram in that space.
3. Final drafts should be:
a. Neatly drawn (outline in pencil first!)
b. Labeled with the names of any relevant chemicals or processes including any bold
words.
c. Have arrows demonstrating the direction that the molecules are moving
d. Be in color – I recommend colored pencils over crayons or markers.
What is NOT ACCEPTABLE
1. You may NOT simply google each cycle and print our a diagram made by someone else.
2. You may not hand draw a picture that you found on the web or in a book
3. You may not have the exact same picture as anyone else in this or any other class.
Using the computer You may use a computer for your final drafts by cutting and pasting pictures of
your diagrams components (ie a tree, clump of bacteria) into your diagram and then drawing arrows and
labels either by hand or using the computer.
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Bio A. Name _______________________________Date____________________________
Water cycle description
Water cycles between the earth and atmosphere through the processes of evaporation (from land or
ocean  atmosphere), transpiration (plant leaves  atmosphere) and precipitation (atmosphere 
the earth). Most evaporation occurs over the oceans. Wind can then push the evaporated water
(clouds) over land. Changes in temperature or elevation of the clouds can produce precipitation. When
precipitation occurs, water can fall either on land or directly into the lakes, rivers and oceans. When
rain occurs on land, water can be absorbed into the soil (infiltration) and remain under the ground as
“ground water”. This water is available to plants through their root system. If water is not absorbed
into the ground, it often travels “downhill” into lakes, streams or into the ocean. Movement of water
from the ground into lakes, streams or oceans is called “runoff”. Rain occurs predominantly over land,
while evaporation occurs predominantly over the oceans. This means that oceans export water to the
land via “the wind”.
Interesting facts about water on earth:
1) The oceans contain about 97% of all the water on earth. Glaciers account for another 2 percent.
That means only about 1% of all the water on the earth is “fresh water” and available for use.
While water in lakes and streams generally flows to the oceans. Water in the ground stays for a
long time (generally longer than a lifetime). Because of this, once ground is polluted, it is very
hard to get rid of the pollution.
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Bio A. Name _______________________________Date____________________________
The Carbon Cycle
The carbon cycle is very important to humans (and all living things). It is one of the primary elements in
humans (and all living things), it is necessary for plant growth, and it is the basis of all human food.
Carbon is usually found as some type of compound (matter that has more than one element). These
forms include CO2 (carbon dioxide) and methane (CH4). These two forms are important in the climate
system, because they affect global temperatures.
Carbon (in the form of CO, CO2 and CH4) is released into the atmosphere from volcanoes, burning of
fossil fuels (industry) or deforestation (ie forest fires), respiration (animals “release” CO2), dissolving of
rocks (weathering), and release from the oceans (diffusion; note this can go both ways). Carbon dioxide
(CO2) enters plants through its leaves and combines with H2O in a process called photosynthesis to
produce sugars, starches, and growth in a plant. Animals eat the plants, thereby transferring carbon
(food) from plant to animal. Animals then release carbon into the air through respiration. The highest
amount of carbon is found in rocks and is released as carbonate rocks (like limestone) weather and
erode. The soil (which is a combination of small particles of rocks and dead and decaying material) also
contains carbon which can be released into the air. As rocks weather (predominantly due to rain),
carbonates (CO3 wash into the lakes, streams and oceans. A final source of carbon are fossil fuels (oil,
gas) created from dead animal and plant that die in the water and are eventually covered with
sediment and compressed into rock.
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Bio A. Name _______________________________Date____________________________
The Nitrogen Cycle
The nitrogen cycle is important because nitrogen is a vital element found in protein (what your muscles
and body are made of) and nucleic acids (DNA and RNA, the molecules who store and copy the code so
that proteins can be made). While we have LOTS of nitrogen (N2) in the air, plants cannot use nitrogen
in this form. So, the N2 needs to be changed to a form that can be dissolved in ground water and taken
into the plant through the roots. Changing N2 into these “dissolvable forms” like ammonia (NH3) and
nitrates (NO3) is done through bacteria that live in the soil or that live in the roots of SOME plants.
Once nitrogen is taken into the plant, it can be transferred to animals (including humans in the form of
protein). All living things eventually die. When living things (plants, animals, fungus, bacteria, etc) die,
they are decomposed (broken down) by bacteria. Some of these bacteria turn the compounds
containing nitrogen (like protein) in living things back into N2 (nitrogen gas) which is then released back
into the atmosphere. This happens in both the ocean and on land. This process is called denitrification.
Some of the nitrogen also remains in the soil in a form that plants can reuse. It is interesting that
lightning can also convert N2 to NH3 or NO3. This is important in understanding how life may have
originally started. We now produce (manmade) fertilizer (which is mostly nitrogen and phosphorus), to
replace nitrogen in land where we harvest crops, but don’t allow the plant material to die and put
nitrogen back into the soil naturally.
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Bio A. Name _______________________________Date____________________________
The Phosphorus Cycle
The origin of phosphorus was rocks. Eons ago, as some rocks weather and erode, phosphorus becomes
available. However, phosphorus release from rocks is very slow. So most cycling of phosphorus in plants
is between living(phosphorus taken in from the soil for growth) and dead plants (phosphorus released
into the soil during decay/decomposition. Phosphorus is transferred into animals when the animals
consume the plants. Rains can also cause runoff of phosphorus into fresh and saltwater. Often when
phosphorus goes into Phosphorus does not transfer very well from the oceans to the land as most of it
ends up in deep oceans. Humans have accelerated phosphorus transfer from rocks to soil and plants by
mining phosphorus and making fertilizer. Sources for phosphorus include guano (seabirds, cave bats
and seal “droppings”) and some very ancient rocks. We are now utilizing phosphorus more quickly than
the earth can “make it”. Phosphorus is critical in the diet (it is a primary element in DNA, RNA and ATP)
and when it reaches critically low levels, we will not be able to grow crops. Interestingly, one of the big
uses of phosphorus is in making carbonated beverages…so start drinking water to conserve phosphorus!
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Bio A. Name _______________________________Date____________________________
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Bio A. Name _______________________________Date____________________________
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