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Form 3 Biology
NITROGEN CYCLE
NITROGEN IN AIR
NITROGEN
ONLAND & LIVING
ORGANISMS
By Mukilya David
WELCOME
Introduction
•
% Composition of Air
video clip-0.2
Intro. Cont.
What is the use of Nitrogen?
• An essential part of Amino acid – structural &
functional.
• An essential component of all living cells
Have you ever thought of how
nitrogen moves from air?
Think of it now.
Video clip 1.0
State what is happening at the
following stage of nitrogen conversion
and discuss
•
•
•
•
Stage 1
Stage 2
Stage 3
Stage 4
Main activity
Removal of nitrogen from air
• Nitrogen fixation
• Decay
• Denitrification
• Nitrification
reinforcement
Biological fixation
• Biological nitrogen fixation
is done by nitrogen fixing
microbes.
• These include rhizobium
bacteria in leguminous
plants the convert nitrogen
gas into nitrates.
• Free living bacteria eg
Azotobacter & clostridium
algae e g Anabena,
Chlorella, nostoc
Non-biological fixation
• Lightening
• Nitrogen is combined with
oxygen to form nitrous acid
and nitric v acid which are
converted into nitrates
• Plants obtain nitrates from
soil and convert them into
plant proteins
• Animals obtain proteins
direct from plants
Returning of nitrogen into air
Dead organisms , wastes saprophytic bacteria and fungi
break down proteins into ammonia
Which is converted into nitrates by nitrifying bacteria eg
nitrosomonas and nitrobacter in a process known as
nitrification.
Soil microbe reduce nitrates to nitrites, ammonia and
even free nitrogen gas through denitrification .these
include
Eg pseudomonas, denitrificans, thiobacillus .
They utilise the oxygen released in the prcess for their
respiration as the nitrogen is released into the
atmosphere.
conclusion
• Methods of removing nitrogen from air
• Methods of returning nitrogen in air
assignment
• Link the different ways of adding nitrogen in
air and the different methods of removing
nitrogen from air using a chart and see what
you will get.
End
•
Thanks
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