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Nature of Science
Unit 1•Characteristics of Life
•Scientific Method•History of the Scientific Method
•Organization of Living Things
What is Science
Observing
Interpret
Explain
CharacteristicsOf Life
Scientific ToolsAnd Procedures
Metric System
Microscopes
What is the Nature of Science?
Knowledge attained through study or
practice
Set of methods or processes
Using observation and experimentation to
describe and explain the natural world
Organized way of using evidence to learn about the natural world.
Do you agree or disagree?
• Science demands evidence• Science is a social activity• Science is a blend of logic and imagination• Scientific ideas are subject to change• Scientific ideas are durable• Science avoids bias• The natural world is understandable
Designing an Experiment
Section 1-2
State the Problem
Form a Hypothesis
Set Up a Controlled Experiment
Record Results
Analyze Results
Draw a Conclusion
Publish Results
Scientific MethodWhat is the scientific method? It is a _______________ that is used to find _______________ to questions about the world around us.
Is there only one “scientific method”? No, there are several versions of the scientific method. Some versions have more ___________, while others may have only a few. However, they all begin with the identification of a ______________ or a ____________________ to be answered based on observations of the world around us and provide an ________________ method for conducting and analyzing an experiment.
What is a hypothesis? It is an ________________ ___________ based on observations and your knowledge of the topic.
What is data? It is __________________ gathered during an experiment.
Defining the Variables• Independent Variable: what you change, this is what
you control
• Dependent variable: the factor in an experiment that you want to observe, the data or what you measure
• Experimental Group: How will each group be different? (the group exposed to the independent variable)
• Constants: the things that stay the same for all the experimental groups
• Control Group: the group that you compare to– No treatment– Experimenter Selected group
Scientific Method
________________
How will you test your hypothesis? Develop a procedure for a reliable experiment and address safety rules.
_____________________What do you think will happen? Predict the answer to your question or the
outcome of the experiment.
__________What do you want to know or explain? Use observations you have made to
write a question that addresses the problem or topic you want to investigate.
______________________________Write a conclusion that summarizes the important parts of your
experiment and the results.
______________________________________________________
Is the data reliable? Does your data and observations from the experiment support your hypothesis?
____________________________________Follow the steps in your procedure to perform your experiment.
Record data and observations!
Communicate the Results
Write a conclusion that summarizes the important parts of your experiment and the results.
_______________________________________
Is your data inaccurate or the experiment flawed?
Analyze the Data Is the data reliable? Does your data and observations from the experiment
support your hypothesis?
Perform an ExperimentFollow the steps in your procedure to perform your experiment. Record data
and observations
____________________Rewrite your procedure to address the flaws in the original experiment.
Experimental Design Template
Problem Statement: (Stated as a testable question)
Hypothesis: (If....Then statement describing the effect that changing the independent variable has on the dependent variable)
Independent Variable (IV):
Dependent Variable (DV):
Constants:
Controls:
Experimenter selected control:
Prior to the 1600's many people believed that nonliving things could spontaneously turn into living things. For example, it was believed that piles of straw could turn into
mice. That is obviously not the case.
Living vs. Non-Living
Redi’s Experiment on Spontaneous Generation
OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat.
HYPOTHESIS: Flies produce maggots.PROCEDURE
Controlled Variables:jars, type of meat,location, temperature,time
Manipulated Variables:gauze covering thatkeeps flies away from meat
Uncovered jars Covered jars
Several days pass
Maggots appear No maggots appearResponding Variable: whether maggots appear
CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur.
Needham
• Looked at growth in broth.• Did not believe Redi’s experiment.• Tried to prove that spontaneous generation
could occur under the right conditions.
• Assumption: heating the gravy killed all the microorganisms
Spallanzani’s Experiment
Gravy is boiled. Flask isopen.
Gravy is teeming with microorganisms.
Gravy is boiled. Flask issealed.
Gravy is free of microorganisms.
Hypothesis? Independent Variable? Dependent Variable? Controls?
Pasteur’s Experiment of Spontaneous Generation
Broth is boiled. Broth is free ofmicroorganismsfor a year.
Curved neckis removed.
Broth is teeming with microorganisms.
Pasteur
Biogenesis (generating from life)All Living things come from other living things!
Why did microorganisms grow after Pasteur broke the neck of the flask?
Theory: a well tested explanation that unifies
a broad range of observations
• Can a Theory change over time?Yes, as new evidence is uncovered, a
theory may be revised or replaced
Scientific Theory vs. Scientific Hypothesis
Scientific Laws-generalizations derived from facts
• Scientific knowledge is based on observation and inference.
• Scientific laws describe what happens, but not how.
• Scientific laws are not meant to be absolutely true for every circumstance.
• Scientific laws may change with new evidence.
Characteristics of Living Things
Characteristic ExamplesLiving things are made up of units called CELLS.Living things reproduce.
Living things are based on a universal genetic code.
Living things grow and develop.
Living things obtain and use materials and energy.
Living things respond to their environment.Living things maintain a stable internal environment.
Taken as a group, living things change over time.
Many microorganisms consist of only a single cell (unicellular). Animals and trees are multicellular.Maple trees reproduce sexually. A hydra can reproduce asexually by budding.Flies produce flies. Dogs produce dogs. Seeds from maple trees produce maple trees.Butterflies begin life as eggs, then become caterpillars, and then become adult butterflies.Plants obtain their energy from sunlight. Animals obtain their energy from the food they eat.
Leaves and stems of plants grow toward light.
Despite changes in the temperature of the environment, a robin maintains a constant body temperature.
Plants that live in the desert survive because they have become adapted to the conditions of the desert.
Levels of OrganizationBiosphere
Ecosystem
Community
Population
The part of Earththat contains allecosystems
Community and its nonliving surroundings
Populations thatlive together in a defined area
Group of organisms of onetype that live in the same area
Biosphere
Hawk, snake, bison, prairie dog, grass, stream, rocks, air
Hawk, snake, bison, prairie dog, grass
Bison herd
Organism
Groups ofCells
Cells
Molecules
Individual livingthing
Tissues, organs,and organ systems
Smallest functionalunit of life
Groups of atoms;smallest unit of most chemicalcompounds
Bison
Nervous tissue Nervous systemBrain
Nerve cell
Water DNA