Nitrogen Cycle Flashcards
1
Q
What is the importance of nitrogen? (N2)
A
- Vital constituent of protein molecules.
- If nitrogen was not available to plants- could not be synthesised and complex life forms could never have existed.
- Forms most of Earth’s atmosphere
2
Q
What two ways can nitrogen enter the soil?
A
Lightning
- Nitrogen from the air combines with other elements in the air and form simple compounds- nitrogen oxides
- Carried to the earth will rain and enter the soil
Certain bacteria in the soil
- use nitrogen gas and covert it to nitogen compounds
- Some bacteria are living freely in the soils
- Others live within the roots of leguminous plants- (peas, clover, beans). Not used within bacteria cells but released into soil
3
Q
How are nitrogen compounds used in the soil?
A
- Absorbed in the soil
- Synthesise organic nitrogen compounds- amino acids
4
Q
How do the nitrogen compounds move?
A
- Herbivores and carnivores carry the organic nitrogen compounds through their particular food chains
- Then nitrogen is incorporated into animal protein molecules
- Nitrogen occurs in waste products of animal metabolism (= products of excretion- like urea)
- Living organisms return the some nitrogen back into the environment
5
Q
How are protein molecules broken down?
A
- Animals (highest trophic level) die- decomposers break down organic compounds of their bodies
- This releases further nitrogen compounds into the environment.
6
Q
The process of protein compounds changing
A
- Ammonification bacteria covert protein molecules to ammonia (NH3)
- Nitrification bacteria convert ammonia to nitrite compounds (contain NO-2)
- Nitrification bacteria convert them to nitrate compounds (contain NO-3)- nitrates are an inorganic from which is reused by plants
7
Q
What bacteria completes the nitrogen cycle?
A
- Dentrifying bacteria in the soil- breaks down nitrogen compounds and release nitrogen gas back into the atmosphere
8
Q
Why the nitrogen cycle almost perfect?
A
- There is little net gain or loss of the nitrogen.
