Bibliographies....

The following sites were used to answer question one, two and four. I had only used the most reliable information to answer the questions.

• Human Body: The excretory system, 2010, Scienceray, Unknown, 18/8/10, http://scienceray.com/biology/human-biology/human-body-the-excretory-system/.
• Animal Systems: Excretory System, 2010, Andrew Rader Studios, Unknown, 18/8/10, http://www.biology4kids.com/files/systems_excretory.html.
• Main function of the excretory system, 2010, ehow Inc., Unknown, 18/8/10, http://www.ehow.com/about_5158376_main-function-excretory-system.html.
• Excretory System, 2010, ScienceDaily LLC, Unknown, 18/8/10, http://www.sciencedaily.com/articles/e/excretory_system.htm.
• Excretory System, Unknown, Library Thinkquest, Unknown, 18/8/10, http://library.thinkquest.org/2824/Excretory.html.
• Excretory System, 2010, Unknown, Unknown, 18/8/10, http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookexcret.html.
• The Excretory System, 2009, Unknown, Unknown, 19/8/10, http://www.blogger.com/post-create.g?blogID=5996839253778279211.
• Diagram of The Excretory System, 2010, Docstoc, Unknown, 19/8/10, http://www.docstoc.com/docs/951733/diagram-of-excretory-system.
• Body System, 2010, The Franklin Institute, Unknown, 19/8/10, http://www.fi.edu/learn/heart/systems/excretion.html.
• Tobacco's Effect on the Excretory System of the Human Body, 2010, Jim Franklin, Unknown, 20/8/10, http://www.ehow.com/about_6460541_tobacco_s-excretory-system-human-body.html.
• Overview Of Human Excretory System and Common Disorders , 2010, Unknown, Unknown, 14/8/10, http://www.ayushveda.com/yoga/yoga-title5/yoga-for-excretory-system/overview-excretory%20-system.htm.
• Ways to Keep the Excretory System Healthy, 2010, Demand Media, Inc., Unknown, 20/8/10, http://www.livestrong.com/article/110605-keep-excretory-system/.
• Your Urinary System and How it Works, Unknown, Unknown, Unknown, 20/8/10, http://kidney.niddk.nih.gov/kudiseases/pubs/yoururinary/.
• What are the Functions of the Skin in the Excretory System, 2010, ehow Inc., Unknown, 23/8/10, http://www.ehow.com/about_5188832_functions-skin-excretory-system_.html.