C.6 The Nitrogen & Phosphorus Cycles(AHL)

IB Biology

R. Price

v. 1 2015

Allott, 649

#1 Nitrogen-fixing bacteria convert atmospheric nitrogen to ammonia#2 Rhizobium associates with roots in a mutualistic relationship#3 In the absence of oxygen, denitrifying bacteria reduce nitrate in the soil

Nitrogen-fixing bacteria convert atmospheric nitrogen to ammonia Use the following terms in the diagram below illustrating how bacteria converts nitrogen to ammonia:

N2 Rhizobium Azotobacter NH3 nodule carbohydrate

Nitrogen Cycle Use the following terms in the diagram below illustrating the nitrogen cycle: Nitrate(NO3-) Nitrite(NO2-) Nitrosomonas Pseudomonas denitrificans Rhizobium

The Phosphorus CycleUse the following terms in the diagram below illustrating the phosphorus cycle: dissolved in waterways

mining (fertilizers & detergents) phosphate in soil

shallow ocean sediments

weathering

#5 The rate of turnover in the phosphorus cycle is much lower than the nitrogen cycle

#4 Phosphorus can be added to the phosphorus cycle by application of fertilizer or removed by the harvesting of agricultural crops#6 Availability of phosphate may be limiting to agriculture in the future.

Sources

Content Allott, Andrew, and David Mindorff. Biology: Course Companion. 2014 ed. Oxford: Oxford UP, 2014. Print. Oxford IB Diploma Programme.

Hebrank, Mary. Teach Engineering. 2013. Regents of the University of Colorado. https://www.teachengineering.org/view_lesson.php?url=collection/duk_/lessons/duk_cellresp_mary_less/duk_cellresp_mary_less.xml

Walpole, Brenda. Biology for the IB Diploma. 2nd ed. Cambridge: Cambridge UP, 2014. Print.

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