Classification and evolution GapFill

Organisms can be grouped into  ecosystemscellsgenestaxa based on their evolutionary relationships using  mitoticanatomicalbiodiversityphylogenetic classification. Organisms are sorted into increasingly small groups based on a hierarchy, starting with  phylum and domainfamily and orderorder and classdomain and kingdom, and finishing with a binomial name consisting of  family and genusgenus and speciesspecies and breedphylum and species, which uniquely identifies a species. These relationships are based on a range of characteristics, but rely mainly on the similarities and differences in widespread biological molecules such as DNA and  hCGcytochrome cchlorophyll aADH.

There are five main kingdoms into which species can be grouped, members of which share different characteristics. For example,  prokaryotaeplantaeprotoctistaarchaea consists of organisms which do not possess nuclei or any other membrane-bound organelles, and  prokaryotaeplantaeprotoctistaanimalia consists of multicellular, autotrophic organisms with a cellulose cell wall.

Natural selection relies on the generation of new alleles. If an allele provides a selective  pressuregenerationsymbiosisadvantage in a certain environment, it is more likely to be passed on to the next generation and increase in frequency within a population. Through this process, species become more adapted to their environments. This may be through:

In some cases, the development of a new adaptation in one species can be problematic for another species. For example, as  antitoxinsallergic reactionsresistanceimmunity to pesticides arises in insects, these chemicals can accumulate in the food chain, causing predators to consume a much larger dose.

Differences in alleles can create variation between individuals, which can be classified in a few different ways. Variation in a characteristic where many intermediates are possible between two extremes is called  discontinuousfrequencycategoricalcontinuous variation, and variation between species is known as  geneticinterspecificspecificintraspecific variation. This variation can be investigated using statistical tests, such as  cladistic testsphylogenetic testsstudent's t-testsstandard deviation tests, which compare two means and provide information about how significant a difference is.