NOTES: Chapter 1.1

What is Science?

What is a “FACT?”

• Something that can be proved or verified by observation or measurementmeasurement

What are some other types of facts

besides the kind you just listed?

Examples: historical facts, scientific

facts, facts read in the newspaperfacts, facts read in the newspaper

Is it possible for a

fact to change?

• It depends on the type of fact.

• Historical facts: No. They already happened.

• Scientific facts: Yes. These facts are based on current knowledge & since we will never know everything, scientific facts can change when new scientific facts can change when new data is discovered.

Science is flexible!

● It is a process and a way of looking at

the world around us. Science explains the

world today, based on research and

evidence we have collected so far.

1.1: What Methods are Used in Science?

What is the Nature of Science / Biology?

Vocabulary:

�Science�Science

�Observation

�Data

�Inference

�Hypothesis

The Goal of Science…

• To investigate and understand nature

• To explain events in nature• To explain events in nature

• To use those explanations to makeuseful predictions

The scientific method makes science different from non-

science.

Science is an organized way

of using EVIDENCE to learn

about the natural world

FossilsDNA

Scientific Method1. Observation: use senses

2. Gather Data from Observations

Quantitative: numbers

(ex: plant height= 32cm)

Qualitative: characteristics

(ex: red hair)

3. Form a Hypothesis using Prior Knowledge Data

4. Test Hypothesis by Observation & Experiment

5. Record & Analyze Data (charts & graphs)

6. Form a Conclusion based on Evidence

Evidence & Observations

How do you make

observations?observations?

Observation vs. InferenceBe careful with your observations!

• Observation: use of one or more of the senses to gather information

• Ex: water tested at 1 site at a lake shows that

the bacteria count is lowthe bacteria count is low

• Inference: A conclusion or interpretation drawn from observationand prior knowledge

• Ex: the entire lake has a low bacteria count

Hypothesis

• Definition: possible explanation for a set of observations

• Useful only if it can be tested!

• Arise from prior knowledge, logical • Arise from prior knowledge, logical inferences, or imaginative guesses

• A hypothesis always has value!

So you’ve made an observation…

• The information gathered from observations is

called…?

• Data can be divided into two types

• Qualitative: descriptions (things NOT • Qualitative: descriptions (things NOT

counted/measured)

• Quantitative: using numbers

Which of the following is an

inference?

a) The plant is yellowish and wilting

b) The plant should be moved to where there is more sun

c) The plant needs waterc) The plant needs water

d) B and C only

e) None of the above

Why Do Scientists Write Lab

Reports?

• So their work can be replicated by

either themselves or other

researchers

– WHY? to assure us that the results – WHY? to assure us that the results aren’t due to chance & that they are accurate

1.2: Science in Context

Vocabulary:

�Controlled experiment

Independent variable�Independent variable

�Dependent variable

�Theory

Remember, the Scientific Method is…

an organized way of

using evidence to

learn about the learn about the

natural world

Steps of the Scientific Method

• observations which lead to a problem

• form a hypothesis (possible explanation for

observations)

• test hypothesis by setting up a CONTROLLED • test hypothesis by setting up a CONTROLLED

EXPERIMENT

• Controlled Experiment – isolate and test effects

of a single variable; everything else is constant

(remains identical between the 2 experiment set

ups)

• Control: the standard in which all the conditions

are kept the same

• Independent Variable: the condition that is • Independent Variable: the condition that is

changed because it affects the outcome of the

experiment

• Dependent Variable: the condition that results

from changes in the independent variable

Prior to the Scientific Method:• Philosophers such as Aristotle tried to explain

their observations of the world though

reasoning

• They thought that special “vital” forces

brought some living things into being from

non-living thingsnon-living things

Recipe for Bees:1. Kill a bull during the first thaw

of winter.

2. Build a shed.

3. Place the dead bull on branches

& herbs inside the shed.

4. Wait for summer. The decaying

body of the bull will

produce bees.

• This idea is called…

SPONTANEOUS GENERATION

– Life from non-life

• It was accepted for centuriescenturies

– Ex: Maggots are formed

from meat; mice from

grain; beetles from cow

dung

Redi’s Experiment on Spontaneous Generation

Independent VariableWhat did Redi change?

Dependent VariableWhat changed as a result & became his data?

What were the variables?

Controlled variables

• jars, types of meat, location, temperature

Independent variable

• gauze coverings• gauze coverings

Dependent variable:

• if maggots appeared or not

Pasteur’s Test of Spontaneous Generation

Was air needed for the spontaneous generation of life?

“ A remarkable

problem solver”

Pasteur’s Test of Spontaneous

Generation

• Pasteur’s experiment:

–Expose the flasks (with boiled broth) to airbroth) to air

–BUT: Protect one sample of broth from microorganisms by curving the neck

Pasteur’s Test of Spontaneous

Generation

• When Pasteur broke the neck of the flask, broth quickly was filled with microorganismsfilled with microorganisms

• His work convinced everyone: ALL living things come from other living things!!

When does a hypothesis become a

theory?

● when a hypothesis is tested and confirmed often enough that it is unlikely to be disproved by future tests

● In science, the word theory applies to a ● In science, the word theory applies to a well-tested explanation that unifies a broad range of observations

● a theory may be revised or replaced as new evidence is uncovered… SCIENCE IS A PROCESS

For your information…

• Theories and laws are DIFFERENT kinds of knowledge

• LAW = generalizations/description of a pattern in nature

• THEORY= explanation of those generalizations

Theories do NOT become laws

(or vice versa)

What is a controlled experiment?

a) An experiment in which the scientist controls

every aspect and records all data accurately

b) An experiment in which there is an

experimental group and a controlled groupexperimental group and a controlled group

c) An experiment in which all groups tested have

many differences between them (they are all

considered experimental groups)