Complete the following concept map
Useful bacteria= nodules of the lequrinous plant = nitrogen fiocation
Answers
Nitrogen fixation is the process in which atmospheric nitrogen is made easily available to the living organisms for various purposes.
In plants, it is needed to make chlorophyll which is used in photosynthesis to make their food. Nitrogen in its gaseous form (N2) can’t be used by most living things. It has to be converted or ‘fixed’ to a more usable form through a process called fixation. Nitrogen gas (N2) diffuses into the soil from the atmosphere and different species of bacteria convert this nitrogen to ammonium ions (NH4+) that can be easily used by plants. Legumes like clover and lupins are often grown by farmers because they have nodules on their roots that contain nitrogen-fixing bacteria.
Symbiotic nitrogen fixation usually occurs in plants that carry nitrogen-fixing bacteria within their tissues. The best example is Rhizobium bacteria and leguminous plants. They both can survive independently, but it is beneficial to both if they are together as they nitrogen fixation takes place.
Relationships that are loose in between the nitrogen-fixing bacteria and the plants are called as associative relationships and the nitrogen-fixing is called as non-symbiotic nitrogen fixation. It occurs in rice roots. In non-symbiotic nitrogen fixation, the bacteria do not require a host plant. The free-living aerobic and anaerobic bacteria in the soil fix the atmospheric nitrogen and increase the nitrogen content of the soil.