ExcretionExcretion

Osmoregulation – Controlling Osmoregulation – Controlling Solutes and WaterSolutes and Water

Nitrogenous WasteNitrogenous Waste

AmmoniaAmmoniaHIGHLY ToxicHIGHLY ToxicCan’t be stored in BodyCan’t be stored in BodyDoesn’t take much energy to produce (good)Doesn’t take much energy to produce (good)Highly Soluble in WaterHighly Soluble in Water

Therefore, used by organisms with a lot of Therefore, used by organisms with a lot of access to water.access to water.

Nitrogenous WastesNitrogenous Wastes

UreaUreaMedium ToxicityMedium Toxicity

Can be carried in body for short period of timeCan be carried in body for short period of time

Medium Solubility – Little water neededMedium Solubility – Little water neededMedium Amount of Energy used to produce Medium Amount of Energy used to produce

this in the Liverthis in the LiverUsed by animals with medium access to water Used by animals with medium access to water

(short period of storage in body)(short period of storage in body)

Nitrogenous WastesNitrogenous Wastes

Uric AcidUric AcidLeast ToxicLeast Toxic

Carried in Body for long periods of timeCarried in Body for long periods of time

Least Soluble in WaterLeast Soluble in WaterWill precipitate out of waterWill precipitate out of water

Most energy used to produceMost energy used to produceUsed by animals where water conservation is Used by animals where water conservation is

premium (land animals with shells)premium (land animals with shells)Lots of Uric Acid produced in shell – white powderLots of Uric Acid produced in shell – white powder

Comparative ExcretionComparative Excretion

If Cells are in contact with environment, If Cells are in contact with environment, NO need for Excretory StructuresNO need for Excretory Structures

Protozoa – No Protozoa – No (Diffusion – OK)(Diffusion – OK)Hydra – NO Hydra – NO (Diffusion – OK)(Diffusion – OK)Planaria – 3 cell layers Planaria – 3 cell layers … See next slide… See next slide