The Science of Biology

Chapter 1

Biology

Ms. Haut

What is Science?

Science aims to understand the natural world through observation and reasoning.

Science begins with observations, therefore, much of science is purely descriptive.

Science uses both deductive and inductive reasoning.

What is Science?

Deductive reasoning uses general principles to make specific predictions.– Example: All turtles have shells. The animal I

have captured is a turtle. I conclude that the animal in my bag has a shell.

Inductive reasoning uses specific observations to develop general conclusions.– Example: All sheep that I've seen are white

Therefore, all sheep must be white

Thinking like a Scientist

• Scientists use a systematic approach to gain understanding of the natural world.– Observation– Question– Hypothesis formation– Prediction– Experimentation– Data Collection– Conclusion

The Scientific Method

• Observations are gathered through your senses

• A scientist notices something in their natural world

• Questions are asked

The Scientific Method

• A hypothesis is a proposed explanation for an observation.– Uses prior knowledge– Must be testable– Allows for predictions

to be made– Typically written in the

“if…, then…” format

The Scientific Method

• The controlled experiment– tests the hypothesis– must be carefully designed to test only one

variable at a time– consists of a test experiment (experimental

group) and a control experiment (control group)

The Scientific Method

• The controlled experiment– An experimenter changes one factor and

observes or measures what happens.– The experimenter makes a special effort to

keep other factors constant so that they will not effect the outcome.

– Those factors are called control variables (constants).

What is the Purpose of a Control?

• Controls are NOT being tested

• Controls are used for COMPARISON, so you can see the effect of the variable

Other Variables

• The factor that is changed is known as the independent variable (manipulated variable)

• The factor that is measured or observed is called the dependent variable (responding variable)

The Scientific Method

• Data Collection

– Results of the experiment• Quantitative data are expressed as numbers,

obtained by counting or measuring.• Qualitative data are descriptive and involve

characteristics that can’t easily be measured.

The Scientific Method

Must Retest

The Scientific Method

• A scientific theory– is a body of interconnected concepts– is supported by much experimental evidence

and scientific reasoning– expresses ideas of which we are most certain