Nature of Science

Unit 1•Characteristics of Life

•Scientific Method•History of the Scientific Method

•Organization of Living Things

Warm Up:

What is the Nature of Science?

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:

Graphing

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

Designing an Experiment

State the Problem

Form a Hypothesis

Set Up a Controlled Experiment

Record Results

Analyze Results

Draw a Conclusion

Publish Results