scientific method how scientists work. how scientists work: solving the problems mmuch of biology...
TRANSCRIPT
Scientific Method
How Scientists Work
How Scientists Work: Solving the Problems
Much of biology deals with solving problems
These problems can be environmental, ecological, health related, etc.
No matter what types of problemsare being studied, scientists use the same problem-solving steps called…
The Scientific Method
Scientific Method Definition
The scientific method is- A logical and systematic approach or
process to problem solving. An organized way of using evidence
to learn about the natural world.
Scientific Method Listing the Steps
Make an Observation Define the Problem Research the Problem State the Hypothesis Experiment to test Hypothesis Collect and Record Data Analyze Data Draw Conclusions Determine Limitations Report Results
Then
And
QuestionQuestion
ResearchResearch
HypothesisHypothesis
Procedure/Method
Procedure/Method
DataData
ObservationsObservations
ConclusionConclusion
What does the scientist wantto learn more about?
What does the scientist wantto learn more about?
Gathering of informationGathering of information
An “Educated” guess of ananswer to the question
An “Educated” guess of ananswer to the question
Written and carefullyfollowed step-by-step
experiment designed to testthe hypothesis
Written and carefullyfollowed step-by-step
experiment designed to testthe hypothesis
Information collected duringthe experiment
Information collected duringthe experiment
Written description of whatwas noticed during the
experiment
Written description of whatwas noticed during the
experiment
Was the hypothesis correct or incorrect?
Was the hypothesis correct or incorrect?
Next
Then
Next
And
Finally
First
Scientific MethodAn Overview
Scientific Method
Let’s break each of these steps down into their individual components:
Ask Question
Do BackgroundResearch
ConstructHypothesis
Test with anExperiment
Analyze ResultsDraw Conclusion
Think!Try Again
Report Results
Hypothesis is True Hypothesis is Falseor Partially True
Experimenting
Let’s look at the text book example of the Scientific Method using Redi’s Experiment on Spontaneous Generation
He was trying to disprove the idea of SpontaneousGeneration (or actually that flies came frommaggots, which camefrom flies)
Francesco Redi Francesco Redi (1668)(1668)
Stating the Problem
Example: How do new living things come into being?
Spontaneous generation once commonly accepted
Redi wanted to show what caused the appearance of maggots (and then flies) on meat
Belief based on prior observations
If leaf lands on water it becomes a fish If bale of hay left in barn it produces mice Muddy soil gives rise to frogs Meat hung out in the market is the source
of flies
Belief based on prior observations
Redi observed that maggots appeared on meat a few days after flies were on meat
No microscope = no way to see eggs
But Redi believed that maggots came from eggs that were laid by flies
Forming a Hypothesis
Redi’s Hypothesis: Flies produce maggots.
How could he test this? Through a controlled experiment
Redi’s Controlled
Experiment
Redi used two groups of jars Jars that contained meat and no cover Jars that contained meat and gauze cover
Jars with meat
Uncovered jars
Covered jars
Control and Experimental Groups
used as a standard of comparison
the group containing the factor (variable) that has been changed
Uncovered jars
Covered jars
Two groups of jars
Control group::
Experimental group::
((manipulated or independent variable))
Variables in an Experiment
Variables - Factors that can be changed Controlled Variables - all the variables that remain
constant Independent Variable - (also called the Manipulated
Variable) - factor in an experiment that a scientist purposely changes
Dependent Variable- (also called the Responding Variable) - the outcome or results, factor in an experiment that may change because of the manipulated variable….what a scientist wants to measure or observe
Variables in Redi’s Experiment
Controlled Variables: jars, type of meat, location, temperature, time
Manipulated Variables: gauze covering that keeps flies away from meat
Let’s think about this.…
1. Which is the control group?
2. Which is the experimental group?
Two groups of Jars with meat
Uncovered jars
Covered jars
Covered jars
Uncovered jars
OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat.
HYPOTHESIS: Flies produce maggots.
PROCEDURE
Manipulated Variables:gauze covering thatkeeps flies away from meat
Uncovered jars Covered jars
Several days pass
Maggots appear No maggots appear
Responding Variable: whether maggots appear
CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur.
Controlled Variables:jars, type of meat,location, temperature,time
Redi’s Experiment on Spontaneous GenerationRedi’s Experiment on Spontaneous Generation
6. Collect and Record Data
Types of Recorded Data Quantitative - observations that involve
measurements/numbers; i.e. 3 days, 12 maggots, 4 g, 13 sec, 8 liters
Qualitative - observations thatdo not involve numbers, are of a descriptive naturei.e. white maggots covered the meat, leaves were all wilting
observations and measurementsmade in an experiment
Data:
Recording the dataRecording the data
Setting up a data tableSetting up a data table
Graphing dataGraphing data
Make a column for each trial, person, or day that you are measuring. You are measuring your DEPENDENT VARIABLE.
Trial or Day 1 Trial or Day 2 Trial or Day 3 AVERAGE OF TRIALS
Vertically list as many groups as you have in this first column. Each group is a different variation of your INDEPENDENT VARIABLE.
Group 1
Group2
Group 3
7. Analyze the Data
Examine data tables, charts, and graphs
Examine experimental notes Look for trends, patterns, and
averages What does the data show Put your data into words
8. Draw Conclusions
Restate the hypothesis:Example: Flies produce maggots.
Accept or reject the hypothesis. Support your conclusion with specific, numerical data. What was Redi’s conclusion?
Flies lay eggs too small to be seen. Maggots found on rotting meat are produced
from the eggs laid by flies. Maggots are not appearing due to
spontaneous generation!
9. Determine Limitations
Scientists look for possible flaws in their research
They look for faulty (inaccurate) data They look for experimental error or bias's They decide on the validity of their results They make suggestions for improvement or
raise new questions
10. Publish Results
Communication is an essential part of science Scientists report their
results in journals, on the internet, or at conferences
This allows their experiments to be evaluated and repeated
Scientists can build on previous work of other scientists
Redi’s experimenton insects generation
What is the differencebetween•Hypothesis•Theory•Law
Introduction to Biology
• Biology is the scientific study of life
• Interactions between different kinds of organisms affect the lives of all
THE SCOPE OF BIOLOGY
• A structural hierarchy of life, from molecules to ecosystems, defines the scope of biology
• An ecosystem consists of:
– Biotic factors
• all organisms living in a particular area
– Abiotic factors
• all nonliving physical components of the environment that affect the organisms (soil, water)
Life’s levels of organization define the scope of biology
• At the top of life’s hierarchy is the ecosystem
• Ecosystems include:
– all the organisms in an area, which make up a community
– interbreeding organisms of the same species, a population
• Organisms are made up of:
– organ systems
– organs
– tissues
– cells
– molecules
• In discovery science, scientists describe some aspect of the world and use inductive reasoning to draw general conclusions
– Example: birds migrate
South each year during
colder months
because it is warmer.
Scientists use two main approaches to learn about nature
THE PROCESS OF SCIENCE
• In hypothesis-driven science, scientists use the “scientific method”
– They propose a hypothesis
– They make deductions leading to predictions
– They then test the hypothesis by seeing if the predictions come true
• The main steps of the scientific method
With the scientific method, we pose and test hypotheses
Experimental Design
• Experiments designed to test hypotheses must be controlled experiments
• Control groups must be tested along with experimental groups for the meaning of the results to be clear
• Independent variable
• Dependent variable
• Grouping organisms by fundamental features helps make the vast diversity of life manageable for study
• Scientists classify organisms into a hierarchy of broader and broader groups
The diversity of life can be arranged into three domains
EVOLUTION, UNITY, AND DIVERSITY
• Most classification schemes group organisms into three domains:
– Domain Bacteria - Domain Eukarya
– Domain Archaea
• All organisms share a set of common features, signs of unity in life’s vast diversity
– All are made of cells
– All have DNA as their genetic blueprint
• These orchids show the variety possible within one species
Unity in diversity: All forms of life have common features
• DNA is made of chemical units called nucleotides
• Each species has its own nucleotide sequence
Characteristics of Living Things:
• The genetic information in DNA underlies all of the features that distinguish life from non-life– Order and regulation
(homeostasis)
– Growth and development
– Use of energy from the environment
– Response to environmental stimuli
– Ability to reproduce
– Evolutionary change
• Charles Darwin is a central figure in biology
• He synthesized the theory of evolution by natural selection
– A theory in science is a comprehensive idea with broad explanatory power
• Evolution is the core theme of biology
Evolution explains the unity and diversity of life
• The theory of natural selection explains the main mechanism whereby all species of organisms change, or evolve
• Evolution happens when populations of organisms with inherited variations are exposed to environmental factors that favor the success of some individuals over others– Natural selection is the editing
mechanism
– Evolution is based on adaptations
• Biology is connected to a great number of important issues
– Environmental problems and solutions
– Genetic engineering
– Medicine
Connection: Biology is connected to our lives in many ways
BIOLOGY AND EVERYDAY LIFE
• Many technological advances stem from the scientific study of life
• Evaluating everyday reports in the press about a large range of subjects requires critical thinking and some familiarity with many areas of biology
Your turn….
1. WAIT for Ms. Allard tell you to turn on your clicker and log in.
2. NO talking. You can use your notes but do not use each other!
3. You will NOT be able to change your answer so be sure you have read and understand the question(s) before you hit SEND!
4. Do NOT log off until Ms. Allard tells you to do so!
The ability to move and use oxygen are 2 characteristics of all living things.
A.) true
B.) false
Biology can be related to our every day lives.
A.) true
B.) false
The core theme of biology is
A.) a hierarchy
B.) the scientific method
C.) DNA
D.) evolution
The prefix "a" means
A.) with
B.) without
C.) single or solitary
D.) one
The prefix "bio" means
A.) self
B.) story
C.) life
D.) study of