5.4 Nutrient Cycles Flashcards
What is extracellular digestion?
Secretion of enzymes outside of an organism and external digestion and only necessary nutrients absorbed
What is sabrobiotic nutrition
Obtaining nutrients from dead organic matter using extracellular digestion
What are mycorrhizae?
Fungi with symbiotic relationships with roots of plants
Why are mycorrhizae so efficient?
- Act like extensions of root system
- Increase S.A for water and ion absorption
- Sponge (store water and soluble minerals and ions)
What is nitrogen fixation?
Atmospheric nitrogen is converted into nitrogen containing compounds
What carries out nitrogen fixation?
- Free floating nitrogen fixing bacteria
- Mutualistic nitrogen fixing bacteria (root nodules of legumes)
What is ammonification?
Production of ammonia from nitrogen containing organic compounds
- Ammonium ions in soil
Usually by saprobionts
What carries out ammonification?
Saprobionts
What is nitrification?
Ammonium ions are oxidised into other nitrogen compounds that a plant can use
What are the intermediates in nitrification?
Ammonium - Nitrite - Nitrate
What carries out nitrification?
Nitrifying bacteria which require aerobic conditions
What is denitrification?
Nitrates in soil converted to atmospheric nitrogen
What carries out denitrification?
Denitrifying bacteria which require anerobic conditions
How can atmospheric nitrogen be introduced into an ecosystem?
Lightning, artificial fertilisers (Haber process), nitrogen fixation
What is the main phosphorous store?
Sedimentary rock
How is phosphorous introduced into an ecosystem?
Weathering of rocks into soil or water bodies
Why are nutrients lost when crops are harvested?
- Removed from ecosystem instead of left to die and decompose
- No return of ions by saprobionts to the soil
- No replace from remains or waste products
What are the types of fertilisers?
Artificial - Inorganic and contain pure chemicals
Natural - Organic matter such as manure, compost, sewage sludge, guano
What are some environmental issues related to fertiliser usage?
- Excess used = leaching and eutrophication
- Changes balance of nutrients
Why are natural fertilisers less likely to leech?
N and P contained in organic molecules that need to be decomposed by microorganisms before plant uptake
- Release into soil more controlled
