1. Topic 12.1 Excretion Mrs.. Jackie

2. Outline the need for excretion in all living organism Define as Removal of metabolic waste from the body. Defined as the removal of toxic substances and substances in excess

3. State that the excretory products in plants include oxygen, and in animals they include carbon dioxide and nitrogenous waste Main excretory substance in plants is oxygen which is released from photosynthesis. Main metabolic waste in animals is nitrogenous waste which results from protein metabolism The main factor that decides what form of nitrogenous waste is removed is the availability of water which varies in different organisms.

4. Discuss the relationship between the different nitrogenous waste products and habitat in mammals, birds and freshwater fish AnimalHabitatNitrogenous waste Adaptation Fresh water fish Fresh waterAmmoniaNo problem with water availability. They can form ammonia which needs to dissolve in water for its removal BirdsLandUric acidNeed to conserve water. Excrete uric acid in the form of a paste that mixes with egested material and comes out from an opening called cloaca. Uric acid is insoluble in water so there is no need of water to excrete it. Help in flying (low weight)

5. Discuss the relationship between the different nitrogenous waste products and habitat in mammals, birds and freshwater fish AnimalHabitatNitrogenous waste Adaptation Humans and other mammals LandUreaHighly soluble in water so there is no need of much water to remove it. Excreted by animals that need to conserve water. Some dessert mammals has efficiency in water reabsorption and hence urine comes out highly concentrated.