Theres this thing called a Gene pool which basically means that any animal that has the same variation of genes, so a zebra and a horse or donkey, would come form the same gene pool. But a monkey and an alegator would certainly not be form the same gene pool. This is also refered to by the phase ecological niche which means that thay have similar physical charactoristic, functions and immunology. So a fish and whale would be in the same ecological neiche but a polar bare and a tookan would not be.
When naming new species there is a binomial sytem. This consits of a generic name and a specific name. The generic name is like our surnames this is normally the greek or latin dirivitive. The specific name is like our first name. This name is not shared between the same genus. So Felil mouse. The mouse is the Generic name and the feild is the specific name. As there are cane mice, white mice, door mice ect.
There are two different types of clasification. Artificial and natural classification. Artificial classification is catorgorising the organisms into groups that are useful at the time. Where as natural classification is based on the species ansesterage. The physical components as well as the genetic components that are passed down during evolution. There is not overlaping.
Each group within a natural biological classification is called a taxon. Taxonomy is the study of these taxons and the hierachy order, known as taxonomy rankings.
When ranking organisms they are first put into a kingdom, then a plyla, which contains organisns that will have a completely different body plan from organisms in the other plylas. The organisms are then put into classes,which is the amound of diversity in each plylas. Next is the order, which are organisms that have additional features in common. These are then separated into families and then into genera, and each genus is separated into species.
Plylogeny is the relationship between the raking of oragnisms and their lines of decent. This can be shown in a family tree which is specifically called a phylogenectic tree. The older members are further up the tree and the newer ones are on the branches below.
How old these records muct be!
Species may be define in terms of their physical charactorisitic and it ability to produce fertile offspring.
If fertile offspring are not prodeced then that line will end very quickly. Such as a mule when donkeys and horse mate. This seams like Mother natures was of saying "Thats not what I want!"
You need to know all the key words that have been highlighted, these will come up. You also need to know the order of all the taxonomy stuff. It will come up!