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Chapter 1 The Science of Biology


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How do scientists test a hyptheses?
By an experiment, a controlled experiement when possible.
How does a scientific theory develop?
When the evidence from many experiments is well supported.
The idea or explanation that life could come from nonliving things.
Spontaneous generation. (just a hyptheses).
Maggots from meat, mice from grain, beetles from poop.
Who proposed that maggots don't just come from meat or from non-living things and what did this scientist do?
Francesco Redi, he said that maggots appear on meat because flies lay eggs on it.
What was Redi's hypthesis?
Flies produce maggots.
How did Redi test his hypothesis that flies produce maggots?
By a controlled experiment. all variables were controleed except the gauze covering the jars to keep the flies off.
In a controlled experiment how many variables are tested at a time?
one at a time,
What was the manipulated variable in Redi's experiment?
The presence or absence of gauze.
What did Redi's experiment do?
Helped dis-prove the hypothesis of spontaneous generation.
What is a controlled experiment?
An experiment where only one variable is changed at a time while all other variables are controlled, or unchanged.
In a controlled experiment, what variable is deliberately changed?
The manipulated variable, like the gauze covering in Redi's experiment.
What is the responding variable in an experiment?
The variable that is observed, and changes in response to the manipulated variable.
What was the responding variable in Redi's experiment?
Whether or not maggots would appear.
Scientific experiments have ________________ of _______________.
standards of documentation.
What do scientists do so that other scientists can repeat and test the same experiment?
Record & analyze their results.
Scientists use the _____ from an _____________ to evaluate the _____________ and draw a _________________.
By drawing a conclusion, scientists do what?
They use the evidence from an experiment to determine whether the hypothesis was supported or refuted.
In Redi's experiment, did his results support or refute his hypthesis.
Supported his hypthesis that maggots come from flies.
What is a Null Hypthesis
In invalid hypothesis
What was one of the first scientific experiments of proper scientific inquire?
Does a single occurrence of an experiment establish it as a fact?
No,scientists repeat and test other scientists experiments
What scientist tested Redi's findings and what was his findings?
Needham tried to prove sponteous generation could occur under the right conditions, gravy boiled but he left the flask open then lots of microorganisms were in the gravy after a few days.
Was Needham's test with the gravy accurate?
Who tested and improved upon Redi's and Neeham's findings?
What did Spallanzani's investigation show?
That microorganisms will not grow in boiled and sealed gravy but only in boiled gravy that is open to the air.
What variable was controlled in Spallanzani's experiment?
Gravy was boiled, flasks used.
What variable was manipulated in Spallanzani's experiment?
One flask left open and the other one was sealed.
Who created a microsope in 1673 that identified micro-organisms, and what did he call these microorganisms?
Anton van Leeuwenhoek, he called them animalcules.
Did the existance of newly found microorganisms make it easier for scientists to come to an agreement of the truth about spontaneous generation>
No, for the next 200 years scientists could not agree if the microorganisms were alive or how they even came in existance.
Who tried to re-prove spontanous generation and was he correct?
Needham reproved it but then Spallanzani's tests proved he was wrong. No living things come from non living things.
What is a key assumption is science?
That experimental results can be reproduced because NATURE behaves in a consistent manner.
When one particulare variable is manipulated in a given set of variable, will the results always be different or the same?
The same.
What did Spallanzani conclude by his experiment?
That nonliving gravy did not produce living things. The living microorganisms came from other ones that entered the open jar.
Who used a long curved flask to improve upon the boiled gravy type of test?
Louis Pasteur, he proved that all living things come from other living things, not just from air.
Which scientists finally settled the argument that living things don't come from non-living things?
Louis Pasteur
It is always possible to test a hypOhesis by an experiment, TRUE OF FALSE.
How do animal field studies differ from controlled experiments?
Animals are observed by watching them, etc.
What is a theory?
A well-tested explanation that unifies a broad range of observations.
What theory is considered absolute truth?
No theory is, but a usefule theory rules over other ones.
How did the design of Pasteur's flask help him successfuly refute the hypthesis of spontaneous generation?
The curved flask didn't allow microorgamisms to enter until he broke the flasks neck, then it started growing microorganisms.
Name an example of a field study of cancer-causing chemicals?
Scientist would not include volunteers with other serious health problems, but only
Name some field studies:
studying animals how they interact with eath other, studying humans that have been exposed to cancer causing chemicals and compare to people not exposed.
A _________ enables scientists to make accurate _____________ about new situation.

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