Scientific Method/Design
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Transcript Scientific Method/Design
Homework:Scientific Method in the
Real World
Find an article or video from
a reputable scientific source
that demonstrates the
application of the scientific
method.
Must be related to some
field of Biology
Scientific inquiry
Experimental Design
In- Scientific Method
Read the last page of the black box
packet.
Write each hypothesis and determine
which would be useful for a scientific
investigation.
Explain each answer.
Create a general statement about the
characteristics of a useful hypothesis
Thru-Scientific Inquiry
Question
Based on observations or information
gained from previous research.
If an experiment can be done or data
can be collected, then a question can be
answered scientifically
Hypothesis
Potential answer to the question
Can be in If, Then format or just a
statement
Only useful if it can be falsified through
experimentation
Variables
Independent Variable-deliberately varied
during the experiment. Affects the
dependant variable.
Can often be time.
May not be directly manipulated by the
investigator, but data can be collected to
evaluate the hypothesis.
Ex: Are more crimes committed during a
full moon?
Variables
Dependant Variable- what is measured
during the experiment
Indicates the effect of the independent
variable
Identify the Variables
The diversity of algal species is
calculated for a coastal area before and
after an oil spill
Guinea pigs are kept at different
temperatures for six weeks. Percent
weight gain is recorded.
A scientist hypothesizes that the adult
weight of a dog is higher when it has
fewer litter mates (brothers and sisters)
as a puppy.
Controlled (standardized)
Variables
Factors that are kept the same in all
treatments
Isolates the effect of the independent
variable on the dependant variable.
Controlled Variables
A scientist wants to determine the effect
of temperature on the amount of chicken
eggs hatched
What is the IV?
DV?
Controlled Variables?
Levels of Treatment
The values set for the independent
variable
Treatment levels are varied to obtain a
broad set of data
Typically based on prior knowledge of
the system.
Control Group
A treatment in which the independent
variable is either eliminated or is set at a
standard value (room temperature, etc.)
Results are compared to experimental
treatments
Identify the control group
A scientist studies the amount of alcohol
produced by yeast when it is incubated
with different types of sugars
The effect of NutraSweet on tumor
development in lab rats is investigated
The effect of light intensity on
photosynthesis is measured by collecting
oxygen produced by a plant.
Replications (trials)
Repeat the experiment several times
using the exact same conditions.
Determines consistent results
Don’t expect the exact same result in
each replication. A certain amount of
variation is expected in biological
systems.
Be sure your sample size is not too small
Out- Experimental Design
A group of students hypothesizes that
the amount of alcohol produced in
fermentation depends on the amount of
glucose supplied to the yeast. They want
to use 5%, 10%, 15%, 20%, 25%, and
30% glucose solutions.