I. Understanding Science

A. What is Science?

1. The goal of science is to investigate and understand the

natural world, to explain events in the natural world, and

to use those explanations to make useful predictions.

2. Characteristics of Science:

Relates only to observable features of the natural world.

Information is collected and organized in an orderly way

looking for patterns and connections.

Proposed explanations are able to be tested- falsifiable

3. Science is: The search for knowledge

Knowledge is the search for truth

4. Scientific Thinking Involves following a pattern:

Make an observation Gather Data Make in inference

5. Observation involves gathering information and data often

using the senses.

6. Data is the information gathered. Data may be of 2 general

types:

Qualitative: not involving numbers, described in words

Quantitative: involves numbers derived from counting or

measuring.

7. Inference is a logical interpretation based on prior knowledge

or experience.

Statement Observation Inference

Object A is round and orange.

Object A is a basketball.

Object C is round and black and white.

Object C is larger than Object B.

Object B is smooth.

Object B is a table-tennis ball.

Each object is used in a different sport.

X

X

X

X

X

X

X

X Object A is a basketball.

Object B is a table-tennis

ball.

Object C is a soccer ball.

Section 1-1

Observation and Inference

II. Designing an Experiment

A. THE SCIENTIFIC METHOD

1. Asking a Question – the question usually

follows an observation

2. Forming a Hypothesis – must be testable

3. Test your hypothesis with a controlled

experiment

4. Analyze & Record Results – scientific

studies always involve detailed

recording of the results. Results may

be recorded in journals, with drawings,

computer spreadsheets, etc.

5. Drawing a Conclusion – Data are used to

either confirm or reject a hypothesis.

Results may be published.

6. Communicate results (Publish)

A Fun Time At Duwop City

B. Hypothesis:

A hypothesis is a proposed scientific explanation

for a set of observations.

1. Characteristics of a hypothesis:

a. developed after initial observations

b. often stated in “If . . . then . . “ form

identifies independent variable and dependent

variable

c. must be able to tested. Testing may be:

1. further observation

2. A controlled experiment

C. Experimental Design for a Controlled Experiment

1. Scientists consider results to be more valid if they are verified

through controlled experiments.

In a controlled experiment, all variables are “controlled” – (kept the

same) except the one variable being tested.

2. Principles of Good Experimental Design

●Test one variable at a time

● Use multiple runs/trials for each experimental set-up

● Allow Control Group to simulate “normal” conditions

● Keep all environmental variables constant except the tested variable.

3. Components of Good Experimental Designs

Well-designed experiments will contain the following:

A. VARIABLES – components that are able to be

changed/controlled/varied in an experiment.

1. INDEPENDENT VARIABLE (aka manipulated variable)

-the item being tested in an experiment

-the item that is different between the set-ups in an experiment

-the item that is part of the experimental design in the

beginning. (The item “I” change

2. DEPENDENT VARIABLE (aka responding variable)

-the results of the experiment

-the difference in the outcome of the experimental set-ups

-what is able to be measured in the experiment.

3. ENVIRONMENTAL CONSTANTS – aka Controlled Variables

- the environmental factors affecting the potential outcome

- the “constants” which need to be kept the same for all experimental trials.

- examples:

amount of water

amount of chemicals (food, fertilizer, atmosphere)

amount of space

amount of light

species involved

specific living environment

amount of time

temperature

B. Control Groups and Experimental Groups

An experimental group or “set-up” is the part of the experiment

which has the independent variable in some modified form.

There may be multiple experimental group set-ups- each one

with a slight change to the independent variable.

A control group:

=a set-up designed to simulate the “normal” conditions or often

the natural environment.

=It is conducted to serve as a standard for comparison.

=It does not contain the independent variable in its modified

form.

=in human studies, the group which is the control group is

referred to as the “placebo”. The group does not receive the

experimental treatment and is not aware if they are or are not

receiving it. (Double Blind Study)

“Sugar Pill”

Go to Section:

Designing an Experiment

Section 1-2

Flowchart

State the Problem

Form a Hypothesis

Set Up a Controlled Experiment

Record Results

Analyze Results

Draw a Conclusion

Publish Results

III. Repeating Investigations:

If scientific studies are to be considered valid, the work must be able to be

repeated or replicated by other scientists and produce the same results. Also,

as other scientists address the concept, a greater understanding will occur as

they add insight to develop a theory.

A scientific example:

In the dark ages, most people believed life could emerge from non-living

material or could readily change forms. Meat gave rise to maggots, mice

came from dirty rags, etc. This was the theory of spontaneous generation.

In 1668, Francesco Redi tested his hypothesis that flies produced maggots in a

controlled experiment. Only one group of meat had the opportunity to be

exposed to flies. Redi believed he had disproved 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 that keeps 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.

Figure 1-8 Redi’s Experiment on Spontaneous Generation

1. Needhams Test of Redi’s Findings – tried to disprove Redi and

again reinforce the idea of Spontaneous generation. Needham

heated gravy and believed that should have killed all

microorganisms. Days later he found many microorganisms and

believed they had spontaneously emerged from the gravy.

2. Spallanzani’s Test of Redi’s Findings – tried to disprove

Needhams work. Repeated and improved the experiment with

longer heating, presence of a control group, and sealing one set

of jars. Conclusion- gravy only produces microbes when

exposed.

Gravy is boiled. Flask is

open.

Gravy is teeming

with microorganisms.

Gravy is boiled. Flask is

sealed. Gravy is free of

microorganisms.

Section 1-2

Figure 1-10 Spallanzani’s Experiment

3. Pastuers Test of Spontaneous Generation –

attempted to disprove spontaneous generation and refute the argument air alone could allow microbes to grow. Pastuer did a similar experiment to Spallanzani but this time improved the shape of the neck of the flasks. Both sets were exposed to air. The control group was open to the air and any falling microbes. The experimental group had bent necks- air in but no microbes. Strong support for refuting spontaneous generation.

Broth is boiled. Broth is free of

microorganisms

for a year.

Curved neck

is removed.

Broth is

teeming with

microorganisms.

Section 1-2

Figure 1-11 Pasteur’s Experiment

Broth is boiled. Broth is free of

microorganisms

for a year.

Curved neck

is removed.

Broth is

teeming with

microorganisms.

Section 1-2

Figure 1-11 Pasteur’s Experiment

Broth is boiled. Broth is free of

microorganisms

for a year.

Curved neck

is removed.

Broth is

teeming with

microorganisms.

Section 1-2

Figure 1-11 Pasteur’s Experiment

Broth is boiled. Broth is free of

microorganisms

for a year.

Curved neck

is removed.

Broth is

teeming with

microorganisms.

Section 1-2

Figure 1-11 Pasteur’s Experiment

4. How a Theory Develops

A Theory is a set of related

hypothesis from scientists in

several different areas which

have withstood repeated

testing.

Theories are widely accepted and

most scientists consider them

to be true. The work of Pastuer

and others gave rise to the

theory of biogenesis- life comes

from life.

IV. General Concepts of Scientific Work

a. Scientists make mistakes and may be influenced by

their own biases when they interpret results:

1. Gender Bias

2. Racial Bias

3. Preconceived ideas about what the results should

be

4. Limited knowledge of the scientist

b. Scientific Work must be published so that:

1. Other scientists can review the work and check it

for accuracy

2. Further investigation can occur

3. Results can influence future decisions- used by

others for the greater good of humanity.

c. If a scientists work is going to be accepted:

1. The experiment must be able to be repeated with the same

results.

2. The scientist must have kept records of their data

(Larger #’s of data = More reliable results)

3. The scientist must be credible.

i. Ethical

ii. First-hand “eye-witness” account

iii. Experiment within his/her own area of expertise.

d. Scientists can be extremely diverse in their backgrounds:

1. Scientists can be male or female

2. Scientists can be of any nationality or ethnicity:

Louis Pastuer – French

Gregor Mendel – Austrian

Charles Darwin – Englishman

George Washington Carver—Black American

e. The Scientific Method Is Limited

1. Some scientific theories can not be completely tested

due to the constraints of time and space. (ie-Big Bang

Theory, Model of the Universe)

2. Some scientific theories are not tested with a

controlled experiment but are represented by models.

3. There is no “fixed procedure” called the Scientific

Method. Instead it represents a general approach used by

many scientists but may be modified by the order of the

steps, kinds of observations, etc.

f. Scientific Theories Change

1. Science as a “body of knowledge” is constantly changing

over time as new discoveries are made.

2. Scientific Theories are “evolving” as new evidence is

discovered.

For example:

Flat Earth Round Earth

Earth Center of Solar System Sun Center of Solar System

Spontaneous Generation Biogenesis

Reclassification of species based on new DNA evidence.

g. Scientific Understanding Changes Society

a. Improvements in Agriculture

b. Improvements in Health & Medicine

c. Improvements in Lifestyle

d. Scientific understanding creates improved technology.

Improved technology creates a deeper scientific understanding.

V. Studying Life A. Characteristics Of Living Things-

1. Cells- All living things are made up of one or more cells.

2. DNA- All living things contain their own genetic code. This provides the instructions they need to live, grow, and reproduce.

3. Reproduction- All living things are able to make more of their own kind

Sexual Reproduction- male & female cells unite to make a new cell with new DNA.

Advantage: Diverse DNA- new combinations of traits- species more likely to survive threats.

Disadvantage: Energy must be spent in securing a mate

& Some inferior offspring produced

Asexual Reproduction- one cell/tissue from a parent develops to produce a new organism with DNA identical to the parent.

Advantage: Less energy needed for reproduction

Disadvantage: Populations DNA is not very diverse- vulnerable to threats

4. Growth & Development-

Growth- increasing in size by making more cells

Development- maturing and going thru change

5. Metabolism- Living things have the ability to bring in food which contains energy storing molecules, break it down and use that energy to power their own tissues.

6. Responsiveness- living things are able to respond to stimuli in their environment such as changes in heat, light, predators, etc.

7. Homeostasis – living things are able to adjust and maintain stable internal conditions despite changes in their external environment.

8. Evolution- taken as a group, species are able to change over time.

Characteristic Examples Living 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.

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.

Flies begin life as eggs, then become maggots, and

then become adult flies.

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.

Section 1-3

Characteristics of Living Things

C. Branches of Biology

Living things can be studied at many different levels:

1. Biosphere – All of the earths areas where living things

exist in ecosystems.

2. Ecosystem – Community and its nonliving environment.

3. Community – Populations living together in a defined area.

4. Population – Groups of one type of organisms living in the

same area.

5. Organism – Individual living things

6. Groups of Cells – Tissues, organs, and organ systems

7. Cells –Smallest functional unit of life

8. Molecules –Groups of atoms linked together to form

chemical compounds.

Go to Section:

Biosphere

Ecosystem

Community

Population

The part of Earth

that contains all

ecosystems

Community and

its nonliving

surroundings

Populations that

live together in a

defined area

Group of

organisms of one

type that live in

the same area

Biosphere

Hawk, snake, bison, prairie dog, grass, stream, rocks, air

Hawk, snake, bison, prairie dog, grass

Bison herd

Section 1-3

Figure 1-21 Levels of Organization

Go to Section:

Organism

Groups of

Cells

Cells

Molecules

Individual living

thing

Tissues, organs,

and organ systems

Smallest functional

unit of life

Groups of atoms;

smallest unit of

most chemical

compounds

Bison

Nervous tissue Nervous system Brain

Nerve cell

Water DNA

Section 1-3

Figure 1-21 Levels of Organization continued