<span>Selective breeding is the process of breeding plants and animals for particular traits.</span>
Bacteria is important because this bacteria binds hydrogen molecules with the gaseous nitrogen to form ammonia in the soil. During assimilation, or when plants take up nitrates from the soil, bacteria aid in the process with the plants in making ammonia. Animal wastes is also a major place where bacteria thrives and produces ammonia. The process in which assimilation occurs in plants, and then bacteria converts the nitrates to ammonia is called ammonification. From the conversion of ammonia to nitrites, bacteria also aids in this process called nitrification. The nitrifying bacteria mostly present in soils, oxidize ammonia into nitrites, and from nitrites to nitrates.
Finally, the process of denitrification also has bacteria present to aid in converting nitrates back into a gaseous form of nitrogen in the atmosphere.
If you look at Cosmos episode 1, I'm sure you find an answer there.
The short answer is that cells respond to the chemical environment in which they find themselves. The cells around them, the specific conditions, and feedback from the environment all create specific chemical cues that inform the cells to which genes should be expressed, and in what amounts. Chemicals include hormones, cytokines, general signaling molecules, such as cAMP, etc.
i literally hopped on google for this, lol.
i hope this helps though. :)
