3. Introduction
•A biology investigation usually starts with an
observation—that is, something that catches
the biologist’s attention.
•For instance, a cancer biologist might notice
that a certain kind of cancer can't be treated
with chemotherapy and wonder why this is
the case.
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10. Most everyone who thinks about how to solve
problems in a formal way has run across the
concepts of deductive and inductive reasoning.
19. A hypothesis is an educated guess,
or an untested explanation, that is
based upon observations or know
facts. For example, if an
entomologist guesses that gray
moths survive better on gray tree
trunks, he or she has constructed a
hypothesis. This hypothesis can be
tested in one or more experiments
or tests.
If a hypothesis has been repeatedly
tested and has not been disproved,
it may become accepted as a theory.
Examples include cell theory and
atomic theory.
A law describes what happens, but
does not explain how it happens.
One example is the law of gravity.
