5.4 Nutrient cycles Flashcards
4 stages of the nitrogen cycle
1- Nitrogen fixation
2- Ammonification
3- Nitrification
4- Denitrification
Why can’t organisms use nitrogen directly from the atmosphere?
N2 is very stable due to strong covalent triple bond.
What is nitrogen fixation?
The process of converting nitrogen gas in the atmosphere to ammonia.
What is nitrification?
The process of converting ammonia to nitrites then nitrates.
What is denitrification?
The process of converting nitrites then nitrates to nitrogen gas in the atmosphere.
Nitrogen Cycle Stage: Nitrogen gas in atmosphere to ammonia
Nitrogen Fixation
Nitrogen Cycle Stage: Ammonia to nitrites then nitrates
Nitrification
Nitrogen Cycle Stage: Nitrites then nitrates to nitrogen gas in atmosphere
Denitrification
Nitrogen Cycle Stage: Dead organic matter to amino-acids
Saprobioitc Nutrition
Nitrogen Cycle Stage: Amino-acids to ammonia
ammonification
What is saprobioitic nutrition?
The process of converting dead organic matter to amino acids.
What is ammonification?
The process of converting amino acids to ammonia.
What carries out nitrogen fixation and where?
Nitrogen fixing bacteria in soil and root nodules of legumes.
What carries out nitrification and where?
Nitrifying bacteria in the soil.
What carries out denitrification?
Denitrifying bacteria.
What sort of process is denitrification?
Anaerobic.
What carries out saprobioitic nutrition?
Saprobionts.
What is and the process of ammonification?
Nitrogen compounds in waste products (e.g. urine and faeces) and dead organisms are converted into ammonia by saprobionts
This ammonia forms ammonium ions in the soil
what carrier out ammonifiacation
saprobionts
What is and the process of nitrification?
The ammonium ions in the soil are converted by nitrifying bacteria into nitrogen compounds that can be used by plants, known as nitrates
1- nitrifying bacteria convert ammonium ions into nitrites
2- nitrifying bacteria then convert these nitrites into nitrates.
What are saprobionts?
A type of decomposer including some fungi and bacteria.
what is and the process of Denitrification
Denitrifying bacteria use nitrates in the soil during respiration
This process produces nitrogen gas, which returns to the atmosphere
This process occurs in anaerobic conditions - in waterlogged soil
In what conditions does denitrification occur?
Water-logged soil.
what is and the process of nitrogen fixation
Atmospheric nitrogen gas is converted into nitrogen-containing compounds
carried out by nitrogen-fixing bacteria
- convert nitrogen into ammonia, which forms ammonium ions (in solution) that can then be used by plants