The Nitrogen Cycle Flashcards
state two things that plants need nitrogen for
To build amino acids, which are then synthesized into proteins during protein synthesis.
to build organic bases(nitrogenous bases) which are used in building nucleotides and nucleic acids
In what forms do plants absorb nitrogen
Do plants absorb nitrogen gas?
As nitrates and ammonium ions through their roots
No, they don’t
what percentage of the carbon dioxide taken in during photosynthesis is converted into proteins by plants
approximately 30%
state the processes involved in the nitrogen cycle
nitrogen fixation
nitrification
de-nitrification
ammonification
the four bacteria that are essential in the nitrogen cycle (and their functions)
putrefying bacteria and fungi( they decompose the in dead animals and plants )
nitrifying bacteria, i.e Nitrosomonas and Nitrobacter.( they convert ammonium ions nitrites and then nitrates)
de-nitrifying bacteria (they convert nitrates back into nitrogen gas )
nitrogen-fixing bacteria (to supply plants with the vital nitrogen that they cannot obtain from the air themselves)
what happens after dead plants and animals are decomposed
their proteins are digested into amino acids, which are then deaminated to form NH2. The NH2 is reduced to produce ammonium ions.
what is required for nitrifying bacteria to function and why
where are these bacteria found then
oxygen.
because they are aerobic.
they are found in aerated soils
the two types of nitrogen-fixing bacteria
azotobacter
rhizobium
azotobacter and it’s function
nitrogen-fixing bacteria that live freely in the soil. they can absorb nitrogen gas from the air and reduce it to ammonium
rhizobium
nitrogen-fixing bacteria found in root nodules. the bacteria and the plant have a symbiotic relationship where the bacteria benefit by having food (sucrose) and shelter and the plants benefit by having amino acids produced by the bacteria.
the enzyme contained by nitrogen-fixing bacteria and the function
nitrogenase
it catalyzes the reduction of nitrogen gas into ammonium ions
by which process does the nitrogen get transported into the root nodules
diffusion
de-nitrifying bacteria found in the soil
pseudomonas
in what conditions do de-nitrifying bacteria thrive and where do they live as a result
anaerobic conditions
in water logged soils
why do de-nitrifying bacteria live in waterlogged soils
because in these soils, there are few air spaces available, as there is a lot of water filling the air spaces. therefore, there are very few oxygens present in the soil, if any…..thereby providing the anaerobic conditions required by the bacteria
by which process does man produce inorganic fertilizers
the Haber process
how are organic fertilizers(slurry) produced
through intensive animal production
Eutrophication
Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus
algal bloom
where high levels of nutrients particularly nitrogen cause rapid growth of algae
effects of eutrophication
the rapid growth of algae blocks light from reaching photosynthesizing plants in the waters. these plants die as a result
of saprophytic bacteria decomposing the dead plants and respiring aerobically, using up dissolved oxygen in the waters. this leads to high biological oxygen demand.
this decreases biodiversity in the habitat (waters).
nitrite and nitrate can also have a direct toxic effect on humans if found in the water supply
4 measures to put in place to reduce eutrophication
restrict the amount of fertilizers applied to the soil
only apply the fertilizer when the plants are actively growing
crop rotation
try to avoid leaving the land bare as this encourages the leaching of nutrients from the soil
TWO WAYS IN WHICH WE CAN INCREASE THE AMOUNT OF OXYGEN IN THE SOIL
through ploughing
by installing drainage systems to reduce waterlogging, thereby enabling natural aeration of the soil
ploughing
the process of turning the soil over to increase the oxygen content of the soil
in which conditions do nitrifying bacteria thrive
aerobic conditions
