The Scientific Method

BIOLOGY is the study of living things

AN ORGANISM is a living thing

The scientific method is a special sequence of investigative steps used to obtain unbiased new knowledge about the natural world

Observation Hypothesis Experimentation Data Conclusion Theory Principle

An experiment is a practical test carried out under carefully regulated conditions

A hypothesis is an educated guess based on observations made

Data consists of the measurements, observations and information gathered from experiments.

Resuts are pubished in a scientific journal so that the experiment can be replicated, examined, and analysed by others

Edward Jenner discovered that if someone was infected by cowpox, they became immune to smallpox. He proved this by injecting a young boy with pus from a cowpox victim and then from a smallpox victim when he had recovered. The boy did not contract smallpox. The word vaccination now comes from the word vacca or cow in Latin. Unsafe, bad experimental design

A theory has been supported by many different experiments and has not yet proved itself to be untrue.

A principle/law  arises from a theory that has shown itself to be valid when fully tested over a long period of time.

A VARIABLE is a factor that may change in an experiment.

A CONTROL is used to provide a standard against which the test/actual experiment can be judged. There should be only one variable between the test experiment and the control.

PRINCIPLES OF EXPERIMENTATION Careful planning and design - variables Safety Control Fair - sample size, random selection, double blind testing, replicates

A replicate is a repeat of an experiment

LIMITATIONS The extent of our knowledge Ethical issues Changes in the natural world Basis of investigation - bad design etc Accidental discoveries Interpreting results

ALEXANDER FLEMING accidentally discovered penicillin by leaving a petri dishof bacteria uncovered. It became contaminated with a fungus that released a chemical called penicillin and kiled the bacteria - antibiotics. Good interpretation of results and careful observation.

Thalidomide was used in the 1950s to combat morning sickness in pregnant women. It had only been tested on animals and had not been proven to be safe for humans and it resulted in deformities in many babies. Results wrongly interpreted. Withdrawn in 1961.

Scientific Method Notes

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