Chapter 2: Chapter 2:

The Science of BiologyThe Science of Biology

Scientific inquiry:Scientific inquiry:• Making observations in nature, asking

questions about these observations, and actively seeking answers to those questions

• Data: recorded observations• Quantitative data: observations

recorded as measurements—always involve a number

• Qualitative data: descriptive data (color, sound, shape, texture etc.) – used when numerical data is impossible or difficult to obtain

• Inference: logical conclusion based on an observation; ex. if doorbell rings, then someone is at the door

VariablesVariables

• Variable: condition that can vary in an experiment

• Independent variable:

the factor that is changed or controlled by the experimenter when testing a hypothesis

• Dependent variable:

the factor that is changed as a result of the changes made in the independent variable

Scientific MethodScientific Method• Procedures used by biologists and other

scientists to gather information used in problem solving and experimentation

Scientific MethodScientific Method

ObservationObservation

• Use of the senses to gather and record information about structures or processes

Asking a QuestionAsking a Question

• Based on observations; one or more questions are generated

HypothesizingHypothesizing• Hypothesis: a suggested answer to a well-

defined scientific question; an educated guess• Always written as an

“if…then…” statement

PredictingPredicting

• To test hypothesis it is necessary to make predictions that logically follows from the hypothesis

• A statement made in advance that states the results that will be obtained from testing the hypothesis

TestTest• Testing a hypothesis or prediction by gathering

data under controlled conditions • Controlled experiment: experiment that tests

the effect of a single variable– it will not be influenced by the variable the other

groups are testing

Organizing DataOrganizing Data

• Involves placing observations and measurement (data) in order– charts, tables, or maps

Analyzing DataAnalyzing Data

• Collected and organized data must be analyzed• Graphs are frequently used to display data • Three types of graphs may be used:

– Line graphs– Bar graphs– Pie graphs

Bar GraphsBar Graphs• X-axis: independent

variable• Y-axis: dependent

variable• Used to display

numerical data that is obtained by counting

Line GraphsLine Graphs• X-axis: independent

variable• Y-axis: dependent

variable • Most useful for

showing trends or continuous change

PIE GRAPHSPIE GRAPHS• Uses circle divided

into sections to display data

• Each section represents a part of the whole

• All sections placed together equal 100% of the whole

Forming a TheoryForming a Theory

• A broad and comprehensive statement of what is thought to be true

• Supported by considerable evidence

• Ties together related hypotheses

TermsTerms

• Evidence: collected body of data from observations and experiments

• Model: physical, mathematical, or mental representations of how people understand a process or idea

• Technology: application of scientific understanding for some specific purpose

1. What should you do if your test does not support your hypothesis?

Revise the hypothesis or pose and test a new one.

2. How is a prediction different from a hypothesis?A hypothesis is a possible

answer to a scientific question, while a prediction is a statement about what will happen under a specific set of conditions. Multiple predictions can be based on a single hypothesis.

• Independent variables answer the question "What do I change?".

• Dependent variables answer the question "What do I observe?".

• Controlled variables answer the question "What do I keep the same?".