Unit 1 The Science of Biology Part 1- What is Science?

Definition of science:  An organized way of using evidence to learn about the natural world  Also refers to the body of knowledge that scientists have built up after years of using this process

Goals of Science 1. Investigate and understand nature 2. Explain events in nature 3. Use those explanations to make useful predictions

3 major principles upon which science is based 1. Deals only with the natural world 2. Collects and organizes info. in a careful, orderly way, looking for patterns and connections 3. Proposes explanations that can be tested by examining evidence

 The process of science always begins with an observation. What is this? Using one or more of the senses to gather info.

 Often, after making an observation, scientists form a hypothesis before beginning an experiment. (Plural form: hypotheses)

Hypotheses may be based on: 1. Prior knowledge 2. Logical inferences 3. Careful questioning

 In science, a hypothesis is ONLY useful if it can be tested.

 Okay, so what are some ways that a hypothesis can be tested? 1. Making further observations 2. Careful questioning (This is the biggie!) 3. A controlled experiment

Now, let’s talk EXPERIMENTATION! Experiments are always done after an observation has led to a question, and a testable hypothesis has been developed as a possible answer to that question. The experiment is designed to test this hypothesis!

 In an experiment, the factors that can change are called variables. Examples of variables: 1. Equipment used 2. Type of material 3. Amount of material 4. Temperature 5. Light 6. Time

 Whenever possible, during an experiment, only 1 variable should be changed at a time! All other variables should be kept unchanged, or controlled. This type of experiment is called a controlled experiment.

Control Group : Provides a normal standard to compare to results of experimental group Experimental Group : Identical to control group except for 1 factor- the Independent Variable!

Independent Variable : Variable that is deliberately changed (difference between control group and experimental group) Dependent Variable : Variable that is observed and is affected by the independent variable (changing I.V. changes D.V)

 During the experiment, scientists must collect and record data. After completing the experiment, it is time to analyze the data! Goals of “Data Analysis:” 1. Determine whether data are reliable 2. Determine whether data support or reject hypothesis

 Scientists can then compare their data with other data that were obtained in similar studies. It is also important to determine possible sources of error in the experiment that was performed (scientists DO make errors, believe it or not!). Data is then often displayed in chart or graph form!

 Scientists then use the data from the experiment to evaluate the hypothesis and form a conclusion. Data from an experiment may disprove a hypothesis, but it cannot definitively prove the hypothesis, in can only support it. Therefore, acceptance of a hypothesis is always tentative, and can be revised based on new data.

As evidence from numerous investigations builds up, a particular hypothesis may become so well supported that scientists consider it a theory. *** The definition of “THEORY” in science is different than the way it is often used in everyday language!***

Scientific definition of theory : a well-tested explanation that unifies a broad range of observations In other words, a theory is not the same as a hypothesis! A theory has supporting evidence, and is accepted by scientists as the probable explanation for the phenomena that has been observed!

Examples of some scientific theories: 1. Plate tectonics 3. Cell Theory 2. Evolution 4. Big Bang

 Why is it so important for scientists to share the results of their experiments? So scientists can evaluate/test each other’s work and build on findings to continue the work

How do scientists typically share their results? Publishing a description of their investigation in a scientific journal

Definition of peer review : scientists who are experts in a field anonymously read and critique an investigation - enough info. provided to duplicate exp.? - good controls? - accurate conclusion? - clearly written paper?