Nitrogen cycle 0.0 / 5 ? BiologyEcology, ecosystems and environmental biologyA2/A-levelWJEC Created by: Autumn Rose NotherCreated on: 04-03-15 11:28 Nitrogen can exist as... A diatomic molecule, part of an organic molecule, part of an inorganic molecule 1 of 23 What organic molecules contain nitrogen? Proteins, Nucleotides, ATP 2 of 23 The four stages for nitrogen to pass from one living organism to another: Consumption, Digestion, Absorption, Assimilation 3 of 23 Type of bacteria that breaks down dead plants/animals, faeces and urine: Saprobiotic 4 of 23 What is meant by the term Saprobiotic? Extracellular digestion by releasing digestive enzymes onto the food source across their body surface. 5 of 23 Another word for decay and decomposers... Purefaction, putrefying bacteria 6 of 23 What is meant by the term ammonification? Proteins being broken down into ammonium ions by ammonifying bacteria 7 of 23 First stage of nitrification: Ammonium ions oxidised to form nitrites by nitrifying bacteria 8 of 23 Example of nitrifying bacteria that oxidise ammonium ions... Nitrosomonas 9 of 23 Second stage of nitrification: Nitrites oxidised to form nitrates by nitrifying bacteria to form nitrates 10 of 23 Example of nitrifying bacteria that oxidise nitrites... Nitrobacter 11 of 23 Why do these bacteria do it? Energy is released during the oxidation which is then used to fix carbon dioxide and then synthesise organic molecules 12 of 23 What happens to the nitrates and any extra ammonium ions? These ions are taken up by the roots of plants by active transport in the root hair cells 13 of 23 What is the free living nitrogen fixing bacteria? Azotobacter 14 of 23 What is the nitrogen fixing bacteria forming a symbiotic relationship with legumes? Rhizobium 15 of 23 How does the Rhizobium benefit from the relationship? Provided with: anaerobic conditions, carbohydrates from plants 16 of 23 How does the legume benefit? Provided with a supply of usable nitrogen containing compounds 17 of 23 What is meant by the term denitrification? Whan nitrate ions are reduced to form Nitrogen gas and oxygen for respiration 18 of 23 An example of this kind of bacteria... Pseudomonas 19 of 23 Where do these bacteria live? Anaerobic conditions such as flooded soil 20 of 23 What is the result of the presence of these bacteria? The area lacks available nitrogen sources (especially for plants) 21 of 23 How can you improve this? Ploughing and drainage of flooded soil 22 of 23 How does this help? Aerates the soil and encourages the growth of nitrifying bacteria 23 of 23
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