Traditionally biology has been organised along natures organisation level; from the scale of cells and molecules to the global scale of the biosphere.
As the wikipedia describes:
Biology is a vast subject containing many subdivisions, topics, and disciplines.
Among the most important topics are five unifying principles that can be said to be the fundamental axioms of modern biology.
Subdisciplines of biology are recognized on the basis of the scale at which organisms are studied and the methods used to study them:biochemistry examines the rudimentary chemistry of life; molecular biology studies the complex interactions of systems of biological molecules;cellular biology examines the basic building block of all life, the cell; physiology examines the physical and chemical functions of the tissues,organs, and organ systems of an organism; and ecology examines how various organisms interrelate with their environment.
Biology evolved over the years. The Human Genome Project and the resulting vast dat stream is at the basis of a shift in the speed of the develoment of biology. Due to the enormous increase in data and the acquired ability to process these data biology has now reached the poiunt where it no longer is limited to describe parts of living systems. This opens entire new fields of research and is one of the promises of this century of Biology.
This devlopment inspired several institutes to produce exciting documents. This trend can be summarized as "new biology" Which is in general a combination of traditional biology, chemistry, physiscs and most importantly the use of mathematics.
One publication from the American Academy of sciences on New Biology is particulary interesting.
And in the UK there is another interesting vision document on the same subject.