Biology is the study of living things, which are also known as organisms. To determine what makes something alive, we must consider the characteristics that are common to organisms.
Though there are many different kinds of organisms, all organisms share these characteristics:
Some nonliving things have some of these characteristics, but to be alive, something must have all of the characteristics. A crystal, for example, has a high degree of order and can grow, but it does not maintain homeostasis.
It's important to understand the basic characteristics of life, so please be sure to review them here.
The levels of organization in biology are characterized by increasing complexity and order, and structured in a hierarchical (or nested) arrangement. For example, atoms of different types form more complex structures called molecules. Molecules, in turn, can form more complex structures called organelles, and so on. You should be able to list the levels of organization, from atoms all the way up to the biosphere. What makes each level different from the level below it (or the level above it)?
To help you make sense of the levels of biological organization, review this lecture, which addresses the biological hierarchy starting at 15:10.
Science is a logical system of inquiry. As such, science allows us to learn about ourselves and the universe in which we live. A critically important aspect of science is that it is based on evidence, and is observational. Beyond mere observation, though, science involves systematic testing of hypotheses. A hypothesis is an explanation of an observation. A hypothesis (which might be correct or incorrect) attempts to explain why something is the way it is.
The active part of science is the devising of experiments to test hypotheses. A hypothesis is supported (though not proven) if an appropriate experiment yields results that are predicted by the hypothesis. Otherwise, the hypothesis must be modified or rejected. This basic process is how we have come to learn about the universe. Biology is the corner of science that deals with living things in the universe, but biology is otherwise no different from science in general.
As you review the nature of science, pay particular attention to the steps in this flowchart, which demonstrates how science is a process. You should also understand the distinction between basic and applied science.
Be sure you understand these terms as you study for the final exam. Try to think of the reason why each term is included.