2-3 nitrogen cycle. nitrogen cycle nitrogen – production of proteins and nucleic acids 79% of...
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Nitrogen Cycle Nitrogen – production of proteins and
nucleic acids 79% of atmosphere – N2 gas Most plants and animals cannot capture
nitrogen from the atmosphere Plants: Use nitrogen in the form of NO3
-
nitrates to produce amino acids then proteins Animals eat plant protein digest it into
amino acid use amino acids to build animal protein in the cells
Nitrification Animals produce waste, die and
decay Nitrogen compounds introduced to
soil Bacteria work on compounds
breaking them into ammonium compounds then nitrates
Nitrates are absorbed by plants
Nitrogen Fixation Nitrogen Fixation: process of converting
atmospheric N2 into nitrates (NO3-) and
ammonium ions (NH4+)
Nitrogen-fixing bacteria: found on nodules of roots (legumes, alfalfa) Rhizobium convert N2 to nitrates to be used by plant
plant gives bacteria sugars excess nitrates move into soil
Nitrogen Fixation Lightning - N2 reacts with O2
- Nitrates are produced
Nitrates fall to earth, enter soil, move into plants through the roots
Crop rotation - balances input and output of N2
Denitrification Denitrifying bacteria: break down nitrates
and nitrites into N2 gas gas reenters atmosphere Denitrifying bacteria carry out anaerobic
respiration found in tightly packed soil and or water logged soil
Aeration slows down denitrification Allow oxygen entry to soil inhibits
denitrifying bacterial growth Keeps grass green by keeping nitrates in the
soil Nitrates are need for chlorophyll (protein)
production
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