Themes of Biology

Biology is known as the study of lives. It is also a field of science that can be unified by some fundamental themes. These themes are:  evolution, levels of organization, structure and function, regulation, unity and diversity and continuity and change. Certainly, all of them have significant meanings in which biology no longer makes sense without any of them.

First I'm going to talk about evlution, which is considered as the "core theme of biology". Evolution can be simply said as change of species over time. The central ideas is that all living organisms on earth share a common ancestor, and as time passes, huge diversity of lives are created through the process of mutation and modification. Mutation is just the permanent change of DNA sequence in a gene. It happens when organisms are producing offsprings, their genes that're inheritted have been altered due to various reasons, such as: enviromental agents, duplication error. A small change of DNA sequences can causes significant changes in organism's looking, behavior and physiology. Therefore, diversity of lives are formed in populations over generations.In addition, organisms' appearence is affect not only by the genetic makeup, but also by its living enviroment.

An exmaple of mutation in DNA

However, evolution is'nt just about mutation and diversity. Another important idea  about evolution is natural selection and adaptation. The enviroment on earth changes over a certain period of time, and only those organisms with certain characteristics that help them to adapt the new enviroment the best are likely to live the longest and produce the most offspring and therefore passing on their certain characteristics. This is called natural selection, the key mechanism of evolution proposed by Charles Darwin. There are many evidences for this theory, the most famous ones are the fossil records, DNA studies and artifical election.


Charles Darwin

In biology, the unity of life refers to all the varitation and forms that characterize various organisms. However, all living things came from one organism, relate to ecolution. These two ideas make up the theme of "unity and diversity". Although lives have huge variations, ranging from bacteria to fungi to animalia, all of them are united by some properties: replication, heritability, catalysis and energy utilization. These four common basic  properties chracterize all living organisms on earth.

Unity and diversity of all living organisms

Another important idea about biology I've learnt is the close correlation between structure and its function. Structure and function are correlated at all levels of biological organization, in which structure determines function. For example: protein (amino acids) structure directly effects its function. It is a lock and key method that cannot work unless the structure fit together. When they fit they can carry out the function of speeding up a chemical process. The components and physical properties (structures) of a certain cell have huge influence on its function.


Structure and function of protein

I've only talked a small section of biology, and there are much much more for us to learn. Biology has a wide range and some we still don't understand so far, which is waiting for us discover and explore.