Answer:
Like everything in life, organisation is important. One major reason is the systematic and structural building of the subject into different levels so it becomes easier to study each separately as opposed to the whole in one go.
Also, it shows how each level integrates into the next in a clear and simpler way.
when we study about cells, as the basic building block of living things, we can focus on the cell as a unit and its structures and the multitude of processes that take place within its membrane and without, we learn how living organisms whether unicellular or multicellular survive. The field of microbiology is well suited to that level.
The next level of tissues, illustrates how similar cells interact and form a group.
Going into organs, different tissues have to be compatible so they can perform specific function(s). This surely is important to illustrate the performance of organs as part of systems.
A whole living organism is a collection of all those systems working together and coordinating on a constant and continuous basis to make sure that the biological machinery is fully functional, free of ailments and diseases.
A healthy organism needs to make sure that all levels are in synchrony to be able to survive and pass on its genetic information to the next offspring to ensure the survival of the species