What is Science?
Advanced Plant and Soil Science
B2
Objectives
• Today you will be able to:
– Summarize the definition and importance of
science
– Describe a hypothesis
– Describe a scientific theory
– Compare hypotheses and theories
– Synthesize a hypothesis for given situations
How do we define science?
• Science, as defined by the National Academy of
Sciences, is the "use of evidence to construct
testable explanations and predictions of natural
phenomena, as well as the knowledge generated
through this process."
What does it really mean?
• Science is a tool to understand how the universe
works around us.
• Science is a system of acquiring knowledge.
– A system of observation and experimentation used to
describe and explain phenomena.
• Scientific discovery takes a long time, and is the
interconnection of many different studies and
existing knowledge
Why? Why is it important?
• Through explanations and knowledge gained through science,
we are able to improve our lives.
• What has science done for you?
University of California, Berkeley
Products of Modern Science
• Electricity
– Observations and experimentation by Ben Franklin
and Alessandro Volta in the 1700s pioneered the
way for harnessing the power of electricity.
Products of Modern Science
• Modern Medicine
– Through science, we enjoy the benefits of:
• Vaccines
• Eradication of diseases such as smallpox
• Extended lives through the treatment of once deadly
diseases
– Many people alive today are here because of the
benefits that modern medicine provided them.
Products of Modern Science
• Modern Agriculture
– Science has played a key role in
developing a safe and abundant food
supply in developed countries.
– Specialized biologists (plant breeders)
started developing high-yielding varieties
of crops through new techniques in
breeding.
– Today biotechnology plays an essential
role in further transforming our food
system, ensuring we have a plentiful and
safe food supply for future generations.
Impact of Science on Society
• Those were some examples of products of
modern science. Almost everything we enjoy
today is the result of science.
• Science also enables us to make informed
personal and policy decisions concerning
health, agriculture, economics, etc.
• As a result, it is extremely important to
understand science and distinguish between
“bad science” and “good science”.
• Groups can take advantage of ignorance to
push their agenda.
What is Science?
THE SCIENTIFIC METHOD
The Scientific Method
• As we discussed, science is a system of observation and
experimentation.
• This system of observation and experimentation is the scientific
method. The scientific method is the engine behind science.
• List out what you feel are the steps of the scientific process.
The Scientific Method
General Principles
Define a Question
“How do I synthesize a pesticide to attack a specific pest?”
Observe
Information gathering (literature review)
Forming of a Hypothesis
“Getting pimples is unaffected by eating greasy food”
Test the Hypothesis
Perform an experiment and collect data. The experiment must be reproducible.
Data Analysis
Perform statistical analysis.
Interpret the Data and its Implications
This will provide a starting point for further hypotheses.
Publish Results
This allows others to learn about your discovery and develop further advanced research.
Retest
An important part of the scientific process is testing the work of others to ensure you get the same results.
What is Science?
HYPOTHESIS
Hypotheses
• After your observations/researching existing
information about issue, you will form an
educated guess to answer your question.
• Hypothesis is defined as: “a supposition or
proposed explanation made on the basis of
limited evidence as a starting point for further
investigation”.
Hypotheses
• Basically, it is a suggested solution for an
unexplained occurrence that does not fit into
current accepted scientific theory.
• It must be worded so that it can be tested,
and subsequently answered.
• This is called falsifiability and testability.
Hypotheses
• In order to make it testable, you express your
hypothesis using an independent variable and
dependent variable.
• Independent Variable (IV): variable you
change
• Dependent Variable (DV): you observe
changes of this variable with the changes of
the IV.
EXAMPLE SCIENTIFIC EXPERIMENT
Example Experiment
• Define a Question: “What happens if I water a
plant with different liquids?”
• Information gathering: research on the
methods water is absorbed through the plant
• Hypothesis: “Normal water with little to no
additives is the most effective liquid to water”.
Types of Variables
Independent
Dependent
Control
This is the variable you
change.
You collect data on this
variable based off of
the changes you make
to the independent
variable.
Unchanged, constant.
9
8
7
6
1
5
9
9
8
8
7
7
6
6
1
1
3
5
5
2
4
4
3
3
4
1
Example
Using various liquids to
“water” a plant versus
your control: water.
2
2
1
1
Example
Plant height
Example
Type of plant, soil.
Plant water
Example Scientific Experiment
Raw Data
Water Treatment (IV)
Height
(in)
Soda
Orange Juice
Vinegar
Water
Plant #1
10.2
12.4
4.5
19.8
Plant #2
12.6
11.9
6.7
21.5
Plant #3
11.7
10.5
5.9
21.9
Plant #4
9.8
11.3
6.4
22.3
Example Scientific Experiment
Water Treatment (IV)
Height
(in)
Soda
Orange Juice
Vinegar
Water
Plant #1
10.2
12.4
4.5
19.8
Plant #2
12.6
11.9
6.7
21.5
Plant #3
11.7
10.5
5.9
21.9
Plant #4
9.8
11.3
6.4
22.3
Data Analysis
Soda
Orange Juice
Vinegar
Water
Mean
11.075
11.525
5.875
21.375
Standard Deviation (σ)
1.305
0.818
0.974
1.100
Implications/Conclusion
• What would your conclusion be given this
data?
Soda
Orange Juice
Vinegar
Water
Mean
11.075
11.525
5.875
21.375
Standard Deviation (σ)
1.305
0.818
0.974
1.100
• Recommendations?
We have tested hypotheses – now what?
THE NEXT STAGE: THEORIES
Theories
• A scientific theory is a well-substantiated
explanation for natural phenomena.
– Theory is the result of repeatedly testing and
confirming hypotheses with the use of the
scientific method.
Hypothesis
Hypothesis
Hypothesis
Scientific
Theory
Hypothesis
Theories
• The US National Academy of Sciences defines
theories as:
– The formal scientific definition of theory is quite
different from the everyday meaning of the word.
It refers to a comprehensive explanation of some
aspect of nature that is supported by a vast body
of evidence. Many scientific theories are so well
established that no new evidence is likely to alter
them substantially.
Theories
• The common usage of the term theory does
not reflect scientific theory.
Examples of Theories
• What are some examples of theories?
Examples of Theories
• Heliocentric theory
– The model in which the Earth and planets revolve
around the Sun at the center of the Solar system.
– Is this a fact?
– It serves as an example of how many theories are
well established and no new evidence can
substantially alter them.
Examples of Theories
• Germ theory of disease:
– States that some diseases are caused by
microorganism
• Cell theory:
– Cells are the basic unit of structure in all
organisms and also the basic unit of reproduction.
Distinguishing: Hypotheses and Theories
Hypotheses
• Suggested explanation for
an observable phenomenon
• Prediction of a possible
relationship between two
events
• Very specific – focused on
certain events
Theories
• Well-established, unified
explanation
• Developed after a set of
proven hypotheses
• Based on a wide set of data
• It is a general principle
Identifying
• Hypothesis or Theory?
“If I add a certain amount of growth regulator to
this plant, it will cease growing taller.”
Identifying
• Hypothesis
• Why?
• Specific
• Suggestion, prediction
• Predicting a correlation among events
Identifying
• Hypothesis or Theory?
• “Based on the studying of fossils and the
modern distribution and reproduction of
organisms, natural selection is how life has
developed through the ages.”
Identifying
• Theory
• Why?
• General
• Well-substantiated, unified explanation
• Repeated testing, evidence
ACTIVITY
Activity
• In groups, develop a plan for a scientific
experiment.
• Draw out and explain all the steps for the
scientific theory for your experiment.
• Remember: the scientific process is
methodical and intricate. It’s important to
make sure the experiment is accurate.
ASSESSMENT
Assessment
• What is a scientific hypothesis?
• What are the steps of the scientific theory?
• Describe each step of the scientific theory
– Provide examples
• Compare and contrast hypotheses and
theories