Classification systems function in order to organize a group of organisms into smaller groups according to some kind of logic. For example, the most used classifications system in biology is the phyllogenetic, which classifies living beings according to their evolutive affinity.
In the other hand, a dichotomous key is a "guide" used by biologists when they need to indentify an individual. It is organized in several steps regarding some key characteristics in order to guide you to which species/genus/family your individual belongs to. A dichotomous key never provides any kind of trustworthy phyllogenetic information, and should be understood only as a tool.
Darwin’s theory and the flow of genetic information and how we evolves for example the primates this is an example of evolution. It is the progress of mankind and for creatures
We need to know the dominant and recessive traits of the noombats in order to answer this question. If both of them has yellow as the dominant trait, then green may be recessive. In that case there is a chance for them to have a green bellied child. Its impossible to tell the percentage though because we don't know enough about the animals.
