Topic 5B: Nutrient Cycle Flashcards
What are saprobiants?
Microorganisms that secrete enzymes and absorb desired nutrients from digested dead organisms (extracellular digestion)
What is ploughing?
- This is provides oxygen to the soil
- saprobiants use the oxygen to respire
- so more nitrates/mineral ions given to soil
What is called when organic molecules turn into inorganic molecules?
Saprobiotic nutrition
How does saprobiants respire?
aerobically
How much of nitrogen in the air?
78%
What is nitrogen needed for in plants?
Biological molecules
- DNA
- RNA
- Proteins/AA
What are the stages for nitrogen cycle?
1) Nitrogen Fixation
2) Ammonification
3) Nitrification
5) Denitrification
What is Nitrogen Fixation?
- Nitrogen gas are converted to ammonia then to ammonium ion
- by nitrogen fixing bacteria (Rhizobidium)
What is Rhizobidium?
Root Noodle which has mutuallistic relationship
What is Ammonification?
- dead organisms are decomposed by saprobiants
- converts to ammonium ion to soil
What is Nitrification?
- ammonium ion converts to nitrite by nitrosomas
- Nitrite ions converts to nitrate ions by nitrobacteria
- by nitrifying bacteria
What is Denitrification?
- Nitrate ions in the soil are returned back into the atmosphere as nitrogen gas
- by denitrifying bacteria anaerobically
- respiring out N2 gas
What is mycorrhaze?
-fungi having symbiotic relationship with plant roots
Fungi have long thin strands called?
Hyphae that attaches to roots
Features of hyphae?
- increases SA
- so that more water and scarce ions like phosphate can be absorbed into the plant
How is phosphorus used in organisms?
For biological molecules:
- ATP
- DNA
- phospholipid bilayer
Outline the stages in the Phosphorus Cycle?
- Phosphorus found in rocks
- due to weathering it gets dissolved in soil/ocean
- plant can use there roots which are mycorrhaze so assimilate
- animals eat plants
- animals/plants die and decompose
- by saprobiotic bacteria back into the soil
What is sea bird waste callled?
Guano
What does guano contain?
- high proportion of phosphate ions
- many use it as a natural fertiliser
Why are fertilisers used by farmers?
- Crops get harvested
- animals move around
- so don’t go back to soil
- Farmers need to replace them through fertilising
What is a natural fertiliser?
organic matter like manure/sewage/guano
What is artificial fertiliser?
inorganic matter like ammonium nitrates (pure chemicals)
What does too much fertiliser result in?
- damage to crops and die
- leaching
What is Leaching?
it is caused by when fertilisers used an excess amount.
What is leaching cause?
Eutraphication
What is eutraphication?
- mineral ions/water soluble wash away to lakes/rivers due to heavy rainfall
- mineral ions stimulate rapid growth of algae
- algae blocks light
- so plants under algae receive less light
- less photosynthesis
- plants under algae die and decompose by saprobiants
- saprobiants respire aerobically and uses up oxygen in the water
- less conc of oxygen for fish to respire so they die
What is leaching not common in?
Natural Fertilisers because they already contain organic compounds
