2.2E Nutrient Cycles in Ecosystems
Name:
Date:
(Refer to p. 68 – 91 of BC Science 10)
NUTRIENT CYCLING IN THE BIOSPHERE
Make some notes differentiating nutrients, stores and nutrient cycles.
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Metric measurement units used in the diagrams of nutrient cycles:
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gigatonne: _______________________________
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megatonne: ______________________________
**Complete Act. 2-2A Understanding Nutrient Cycles
THE EFFECT OF HUMAN ACTIVITIES ON NUTRIENT CYCLES
Make some notes the effect of human activities on nutrient cycles.
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What was Biosphere II?
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Energy Flow and Chemical Cycling through Ecosystems
(not in text book)
Energy flow occurs linearly, in one direction, through ecosystems. Energy enters from
______________ and exits as heat loss.
Most of the energy acquired by a given level of the food chain is used for respiration at
that level and escapes in to the surrounding environment as
______________________________________. This energy is therefore unavailable to
the next level of the food chain.
Label the diagram below to differentiate between chemicals cycling through a system and
energy flowing.
THE CARBON, NITROGEN, AND PHOSPHORUS CYCLES
Which five elements limit life in ecosystems?
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Which of the five chemical elements are cycled between living organisms and the
atmosphere?
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How does phosphorus enter the environment?
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Health of the ecosystem depends on a ______________________ of these five
nutrients.
THE CARBON CYCLE.
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Every living thing contains ______________.
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Only _________% of the Earth’s crust is carbon.
How carbon is stored
Short term:
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Long term:
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Define the following:
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sedimentation:
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carbonate: __________________________________________________________
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Refer to THE CARBON CYCLE on p. 8 of your Data Booklet to answer the following.
1. The greatest carbon stores on earth:
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2. The store that contains the least amount of carbon:
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3. The greatest carbon exchange (in gigatonnes) and what is responsible :
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4. The smallest carbon exchange (in gigatonnes) and what is responsible :
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5. What process only releases carbon into the cycle?
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How carbon is cycled through the ecosystem
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Photosynthesis
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The balanced chemical equation for photosynthesis is:
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Also occurs in some micro-organisms, such as _____________________________.
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Makes usable energy for __________________________.
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By eating plants, ___________________ obtain energy and take _______________
into their cells.
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Cellular Respiration
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The balanced chemical reaction for cellular respiration is:
Create a diagram that illustrates the link between these two reactions.
Decomposition
The importance of decomposition in the carbon cycle:
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Other ways carbon is cycled through ecosystems
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The following also play an important part in the carbon cycle, by releasing CO2
into the atmosphere:
 the oceans:__________________________________________________
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 volcanic activity:_____________________________________________
 decomposing trees: ___________________________________________
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 forest fires: _________________________________________________
HUMAN ACTIVITIES AND THE CARBON CYCLE
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Human activities have affected the natural carbon cycle in the following ways:
 Burning fossil fuels:
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 Land clearing/logging:
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THE NITROGEN CYCLE
Which macromolecules is nitrogen an important component of?
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I. Proteins are made up of ________________ acids.
II. DNA is the abbreviation for _____________________________________
DNA is made up of many nucleotides.
View the Nitrogen cycle animation. It is very good.
http://www.mhhe.com/biosci/genbio/tlw3/eBridge/Chp29/animations/ch29/1_nitrogen_cycle.swf
How nitrogen is stored (textbook)
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How nitrogen is cycled through ecosystems
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______% of the Earth’s atmosphere is nitrogen gas.
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Most organisms cannot use it in this form, so much of the nitrogen cycle
involves ______ processes to make nitrogen available to plants, and then in turn
to animals.
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1. ________________________________________
2. ________________________________________
3. ________________________________________
1. Nitrogen Fixation: ________________________________________________
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Can occur in 3 ways:
1. In the atmosphere: _____________________________________
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Compounds formed by _______ and _______ can enter
soil through _______________________.
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Only small amounts
2. In the soil: ____________________________________________
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Bacteria grow in root nodules and legumes.
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Symbiosis -> mutualism: plants get ____________,
bacterial get _____________.
3. In water bodies: _______________________________________
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2. Nitrification: ___________________________________________________________
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 There are 2 stages involving nitrifying bacteria:
1. __________________________________________________________
2. __________________________________________________________
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3. Uptake: _______________________________________________________
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These nitrogen compounds compose plant ______________.
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Herbivores and omnivores then eat plants, and use nitrogen for
_________& ________________ _______________.
How nitrogen is returned to the atmosphere
Denitrification: ______________________________________________
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denitrifying bacteria converted _____________ (______) back to
___________________ (____).
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Should be a _________________ between the amount of fixed nitrogen
and nitrogen returned to the atmosphere.
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N2 is also returned to the atmosphere as ammonia (NH3) through
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How nitrogen is removed from ecosystems
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Excess nitrogen dissolves in ___________, enters the
_______________________, and washes into _________and
____________.
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The nitrogen compounds eventually become trapped in
____________________________________, and will not be
released again until the rock is ________________________.
HUMAN ACTIVITIES AND THE NITROGEN CYCLE
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Due to human activities, the amount of nitrogen in the ecosystem has
__________________ in the last 50 years.
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1. _______________________________________ and
_________________________________ releases nitrogen oxide (NO) and
nitrogen dioxide (NO2).
 Burning also releases nitrogen compounds that increase _____
______________________ in the form of nitric acid (HNO3).
2. ________________________ often use large amounts of nitrogencontaining ______________________.
 Excess nitrogen is washed away, or leached, into the waterways.
 leaching:
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This promotes huge growth in aquatic algae = eutrophication:
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Refer to THE NITROGEN CYCLE on p. 11 of your Data Booklet.
1. What two processes take nitrogen from the atmosphere and where do they occur?
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2. Locate the two stages of nitrification. Name organism(s) and ions involved in the
process.
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3. What is involved in uptake? List the ion(s) involved.
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4. Locate denitrification on the data table. Name organism(s) and ions involved in the
process.
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5. Locate and name another natural process that adds nitrogen to the cycle.
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6. Locate and name two human activities that add nitrogen to the cycle.
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THE PHOSPHORUS CYCLE
Phosphorus is essential for _______________________ in plants and animals
Phosphorus is a part of the molecule that carries _________ in living cells.
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______: adensosine triphosphate
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a special nucleotide that acts as the ‘energy currency of the
cell’. Study this diagram to see what we mean by that:
Here you can see how energy is released from the ATP molecule when it is
hydrolyzed to ADP and phosphate:
How is phosphorous used in plants?
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How is phosphorous used in animals?
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How phosphorus is stored
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Phosphorus is not stored in the ________________________.
 it is trapped in _______________________ (PO43–, HPO42–,
H2PO4–) found in __________ (Earth’s Crust) and
__________________________ in the ocean.
Refer to THE PHOSPHORUS CYCLE on p. 9 of your Data Booklet.
1. List the five phosphorus sinks, in order, from largest to smallest?
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How phosphorus is cycled through ecosystems
Weathering: _____________________________________________________
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Differentiate chemical weathering and physical weathering:
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Weathering doesn’t occur until there is geological uplift.
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Geological uplift: __________________________________
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Refer to THE PHOSPHORUS CYCLE on p. 9 of your Data Booklet.
1. List the eight processes, in order, from largest to smallest involved in the flow of
phosphorus in the phosphorus cycle?
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HUMAN ACTIVITIES AND THE PHOSPHORUS CYCLE
Human activities can either add excess phosphorus to the ecosystem or reduce the
phosphorus supplies in the ecosystem.
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Add excess phosphorus:
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Mined for commercial fertilizers and detergents
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Reduce phosphorus supplies:
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Slash-and-burn practices
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HOW CHANGES IN NUTRIENT CYCLES AFFECT BIODIVERSITY
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Any significant changes to any of these nutrients (____, _____, ____, _____, and _____)
can greatly impact the health and biodiversity in an ecosystem
1.
Carbon: contributing to _______________________
 _______________ carbon in the atmosphere, slight temperature changes and changes in
water level can all affect ecosystem biodiversity
 If one part of the ecosystem is affected/removed, it affects the rest of the food chain/food
web.
2.
Nitrogen: can seriously affect __________ biodiversity
 Some plants better adapted to ______________ nitrogen levels than others and therefore
out complete the less tolerant species.
3.
Phosphorus: can affect _______ _________
 _________________ phosphorus have reduced algae production in some lakes, which is
an important food source for _________________.
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