3.5.4 Nutrient cycles Flashcards
What is the role of saprobionts in ecosystems
Saprobionts secrete enzymes onto dead organic matter to hydrolyse it into soluble molecules which are absorbed and used in respiration releasing inorganic ions into the soil
What is saprobiotic nutrition
Saprobiotic nutrition is the process by which saprobionts obtain energy by digesting dead organic matter externally and absorbing the products
What is the role of mycorrhizae in plant nutrition
Mycorrhizae form a mutualistic association with plant roots increasing the surface area for absorption of water and inorganic ions such as phosphate ions
What is ammonification
Ammonification is the conversion of nitrogen containing organic compounds into ammonia by saprobionts
What is nitrification
Nitrification is the conversion of ammonia to nitrite and then nitrate by nitrifying bacteria in an oxidation reaction
What is nitrogen fixation
Nitrogen fixation is the conversion of nitrogen gas into ammonia by nitrogen fixing bacteria which can be free living or mutualistic in plant root nodules
What is denitrification
Denitrification is the conversion of nitrate to nitrogen gas by denitrifying bacteria under anaerobic conditions reducing the availability of nitrogen compounds in the soil
Why are natural and artificial fertilisers used in agriculture
They replace nitrates and phosphates lost when crops are harvested or livestock are removed preventing nutrient depletion in the soil
What is leaching
Leaching is the process where water soluble nutrients such as nitrates are washed out of the soil into waterways
What is eutrophication
Eutrophication is the enrichment of water with nutrients causing excessive growth of algae which blocks light killing aquatic plants and leading to oxygen depletion from bacterial decomposition killing aquatic animals
