Like the study of all sciences, biology is an attempt to better understand the world around us. Specifically, biology deals with the living things in the world. Biology is divided into zoology –the study of animal life- and botany – the study of plants. This is a very superficial division because there are many creatures that are neither plant nor animal, and many others that scientists have not been able to classify.
Science is a body of knowledge about the living world – of insights about nature- ,the evidence for which is a vast array of facts. What is a fact ? The process of creating “fact” is a very cumbersome and time-consuming procedure. The process goes as follows: observation, question, hypothesis, experiment, theory. Notice that the process does not end in “fact”. Fact –or truth- is a philosophical concept; in science, there are few facts – most of the concepts that we will deal with are theories. Theories are always open to further questioning and refinement and , even, contradiction. This may sound like science is very inexact, but in fact, this is the reason that science has come up with so many accurate descriptions of how the world works.
The theories of science are always open to challenge. This is what makes the established theories of science – such as evolution and atomic forces – so powerful and reliable. They have been sitting like bull’s-eyes for years without anyone figuring out reasonable alternatives. Theories are a general set of principles supported by evidence, and not contradicted by any evidence, that explain some aspect of nature. For a theory to remain valid, it must explain all the evidence, and not have any thing contradict it.
The scientific process begins with the inquisitive mind. First there is a question – “what is this?”, “how does it work?”, “where did it come from?”. Then there is a guess as to the answer which is followed by further observations or experiments. If these efforts support the guess, it becomes an hypothesis. An hypothesis is a tentative, testable explanation for an observed phenomenon. Testable means further experimentation – this is called research. Good research requires several conditions : a single variable, a control, a gold standard, a blinding process and randomization.
Every hypothesis developed in this manner ( in other words, every hypothesis that aspires to be a theory) must be : 1) subject to challenge and revision in the face of new evidence, 2) reproducible and 3) falsifiable. That is the scientific process – a carefully structured, meticulously researched effort to explain some aspect of our world. An hypothesis is not a guess and a theory is not an hypothesis. A theory is as close as we will get to most of the “facts” about the world we study.
What we will study in biology are those things in the world that are alive, whether animal or plant or something else. We will find that whatever they are, they have certain basic similarities. They all use the same information system to control their life (DNA). They all use the same transcription mechanism to convert the information in DNA into products to sustain their life (RNA). They all use the same initial process to convert food into energy (glycolysis). And they all use the same molecule to store that energy (ATP).
There is a hierarchy of organization in the living world. The basic unit of all matter, whether living or non-living, is the atom. The atom is the smallest division of a particular piece of matter that still retains the characteristics of that matter. Atoms make molecules. Molecules make organelles. Organelles make cells. Cells are the smallest unit of life. Cells make tissues, tissues make organs, organs make organisms. A group of organisms is a population. Populations make communities and all the communities make the biosphere.
Could you take all the molecules necessary for life, stir them together and make life ? There is a distinct organization of the molecules and distinct characteristics of that organization that defines life. Scientists quibble over the exact characteristics but most agree on these : 1) living organisms are able to accurately reproduce themselves; 2) living organisms are able to maintain stable internal environments; 3) living organisms ( at least for the short term and in their very local environment ) are able to resist the forces of nature ( entropy and gravity ). This means, for example, that they can move about and that they can make energy and store it rather than dispersing it.
The first step toward an understanding of biology is a backward one . All biological processes depend on the interaction between atoms and molecules – the study of chemistry. Chemistry forms the underpinnings of all biology and without some knowledge of it, the concepts of biology will just be floating abstractions.