The Science of Biology

Biology The study of Life Key aspect of biology: The study of one living thing always involves studying other living things.

Characteristics of a Living Thing Organisms Things that have all the characteristics of life. Characteristics of a Living Thing Organization (cells) Obtain/Use Energy Reproduce Respond to Stimuli Growth Homeostasis Development Adapt to Environment

Life can be studied at the following levels: Description Biosphere Part of earth that contains all ecosystems. Ecosystem Community and its nonliving environment. Community Populations that live in defined areas. Population Group of organisms of one type that live in same area. Organism Individual living thing. Group of Cells Tissues, Organs, and Organ System Cells Smallest functional unit of life. Molecules Groups of Atoms

Human existence depends on the existence of all living things on Earth.

Scientific Method The Scientific Method involves a series of steps that are used to investigate a natural occurrence.

The Scientific Method Observe and form a question. Develop a hypothesis which makes a prediction. Test the prediction. Analyze the data. Form a conclusion. Repeat as needed. Hypothesis Test

Scientific Observation It is acquisition of information from a primary source using the five senses or through collection of data such as with measurements. It is fact-based, specific, measurable, and quantitative. It is NOT an opinion, subjective, or emotional reaction

Testable Questions A question that can be answered by an experiment or investigation It is scientific, specific, focused, and about changing one thing. Non-examples are questions that lead to a research project NOT an investigation.

Hypothesis A hypothesis is an educated prediction based on what is already known. Use if and then statements.

Inference A prediction based on observation. This differs from a hypothesis that is based on what is already known and an inference is based on an observation.

Scientific Theory A successful hypothesis becomes a Scientific Theory. A scientifically accepted general principle supported by a substantial body of evidence offered to provide an explanation of observed facts and as a basis for future discussion or investigation (Lincoln et al., 1990). A theory explains how nature works

Theories So… a theory is a highly successful hypothesis. All hypotheses make predictions. All theories make predictions. All theories can be tested. Result: Any scientific theory is subject to change as our ability to make tests, or make observations of a test’s results, improves with time.

Scientific Law An empirical generalization; a statement of a biological principle that appears to be without exception at the time it is made, and has become consolidated by repeated successful testing; rule (Lincoln et al., 1990) A set of observed regularities expressed in a concise verbal or mathematical statement. (Krimsley, 1995). A law describes what nature does under certain conditions, and will predict what will happen as long as those conditions are met.

Independent Variable The independent, or manipulated variable, is a factor that’s intentionally varied by the experimenter

Dependent Variable The dependent, or responding variable, is the factor that may change as a result of changes made in the independent variable.

Control In a scientific experiment, the control is the group that serves as the standard of comparison

Constants Constants, or controlled variables, are the parts of an experiment that do not change. They are kept the same in every test.