Question

Give an example to show how an undesirable change can be prevented?

Answer 1

1,rhizobia sp. bacteria can be found in the root nodules of legumes. these are swellings (clusters of cells) that can be found along the roots. the rhizobia carry out the process known as nitrogen fixation. plants need nitrogen to produce protein but they can’t take it directly from the air where it is abundant in the form of diatomic nitrogen gas (n2). in order for plants to get nitrogen it must first be incorporated into organic compounds such as amino acids in a process known as nitrogen fixation. the rhizobia absorb nitrogen and use it to make proteins and as a by-product it produces nitrogen-containing ammonium which, unlike the n2 in the air, the plant can take up and use for growth (protein production).
as such we call rhizobia nitrogen-fixing bacteria - they are part of a group of organisms that are vital to the survival of life on the planet. the relationship between legumes and rhizobia sp. is a form of symbiosis called mutualism, where both organisms benefit from each-other - the plant gets usable nitrogen from the ammonium and the bacteria receive organic acids from the plant to use as a food source. this kind of relationship is sometimes written as +/+ (each + sign represents that each organism benefits).
2,many legumes have root nodules that provide a home for symbiotic nitrogen-fixing bacteria called rhizobia. the rhizobia convert nitrogen gas from the atmosphere into ammonia, which is used in the formation of amino acids and nucleotides. the association is symbiotic in that both the plant and rhizobia benefit.
hope this helps you dear