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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