Lesson 1

March 6, 2012

Biology

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What is Biology?

OrganismA living thing.

ObservationGathering information in a careful, orderly way.

DataInformation gathered from observations.

InferenceA conclusion based on experience or evidence.

HypothesisA proposed explanation for observations.

Vocabulary

DESIGNING AN EXPERIMENTAsking a questionForming a hypothesisDoing a controlled experimentRecording and analyzing resultsDrawing a conclusion

Review of Scientific Method

An EXPERIMENT…Can make a discovery.Can test a hypothesis.Can prove a known fact.

Designing an Experiment

Example: how do organisms come into being?In the past, observations showed that some

living things just appeared.Mice appeared in grain.Maggots appeared on meat.

Asking a Question

People thought that the mice came from the grain, and the maggots came from the meat.This idea was called spontaneous generation.

Do you think spontaneous generation is correct?

Asking a Question cont.

A doctor named Redi had a different idea. He observed that maggots appeared on meat a few days after flies were around it.

His hypothesis was that flies made the maggots.

Forming a Hypothesis

A hypothesis is a possible explanation based on observations and evidence.

All experiments begin with a hypothesis.

Forming a Hypothesis cont.

Remember: an experiment tests a hypothesis.Redi wanted to test his hypothesis. He had to

figure out which variable to change.A variable is any part of the experiment that can

change. For example: equipment, material, temperature, light, time.

An experiment should only change 1 variable at a time.

The variable that the scientist changes is called the manipulated variable.

The variables that change as a result of the manipulated are called the responding variables.

Doing a Controlled Experiment

Here is Redi’s controlled experiment. What are the controlled variables? What are the manipulated variables? What are the responding variables?

Doing a Controlled Experiment cont.

Controlled variables: jars, type of meat, location, temperature, time.

Manipulated variables: closing the jarsResponding variable: maggots

Doing a Controlled Experiment cont.

Redi observed that maggots appeared on the meat in the open jars.

No maggots appeared on the meat in the closed jars.

He recorded his findings by writing them down for future scientists.

Recording and Analyzing Results

The conclusion uses evidence from the experiment to state if the hypothesis was supported or refuted.Supported = hypothesis was correct.Refuted = hypothesis was incorrect.

Was Redi’s hypothesis supported or refuted?

What was his conclusion?

Drawing a Conclusion

Redi’s hypothesis was SUPPORTED.His conclusion: flies produce maggots.

Spontaneous generation is incorrect.New organisms come from existing organisms.

This is called biogenesis.

Drawing a Conclusion cont.

What is a theory?

Developing a theory

If a hypothesis is supported by many different experiments, it can become a theory.

A theory is a well-tested explanation that brings many observations together. Theories let scientists make better predictions

about new situations.Sometimes more than one theory is needed to

explain something. For example…

Theories

…kangaroos and koalas!

Why are they only in Australia?

Theories cont.

Oy mate.G’day

The answer can be explained by 2 theories:Evolution (more later in this class)Plate tectonics (more later in Physics)

Theories cont.

Plate TectonicsMillions of years ago, Australia, Antarctica and

South America were all joined in one continent.

This continent broke apart, and Australia became a continent by itself.

EvolutionOrganisms change over time to survive.Since Australia was so far away from other

continents, the animals in Australia changed in unique ways

Theories cont.