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