What is excretion Excretion is the removal of

What is excretion?

Excretion is the removal of metabolic wastes from the body, including substances in the excess of the body’s needs. E. g. Sweat, Urine. Bird droppings

• Carbon Dioxide from R _ _ _ _ _ N is removed by gas exchange organs. Lungs and gills. • Excess water and mineral ions removed by k _ _ _ ‘ s and s _ _ n.

How

• Proteins are broken down into amino acids. • Amino acids in excess may be converted into fatty acid/carbohydrates. • In these conversions the NPart is not used and need to be disposed. Why ? Differences in poop

Something to ponder about…. . Why is there different forms of Excretion in different animals ?

Ammonia – Ammonotelic – Ammontelism It is the type of excretion in which ammonia is the main nitrogenous waste material. Such animals are called ammonotelic.

Seen in fish and other aquatic groups because: • Ammonia is formed when protein s are broken down. • Highly toxic and needs to be excreted quickly. • Highly soluble in water • Needs a large amount of water to dissolve ammonia (Roughly 300 to 500 ml for every gram !) • Not a problem for animals living in water throughout.

Work out which animals would give out urea and uric acid and why. Note: Urea – less toxic than ammonia – less water required to dilute. Uric acid – virtually non toxic – excreted as solid/semi solid(as almost insoluble in water)

Excretion and Egestion – What’s the difference ?

References • • • www. tutorvista. com www. cartoonstock. com NCEA year 12 biology study guide