The document summarizes key concepts in science including the scientific method, characteristics of living things, and levels of biological organization. It discusses how early scientists like Redi, Needham, Spallanzani, and Pasteur designed and repeated experiments to disprove spontaneous generation and develop the theory of biogenesis through controlled experiments. Their work established principles of experimental design still used today.

1. 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

2. 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.

3. Observation and Inference
Section 1-1
Statement Observation Inference
Object A is round and orange. X
Object A is a basketball. X
Object A is a basketball.
Object C is round and black and white. X Object B is a table-tennis
ball.
Object C is larger than Object B. X
Object C is a soccer ball.
Object B is smooth. X
Object B is a table-tennis ball. X
Each object is used in a different sport. X X

4. II. Designing an Experiment A Fun Time At Duwop City
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)

5. 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

6. 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.

7. 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.

8. 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

9. 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”

10. Flowchart
Section 1-2
Designing an Experiment
State the Problem
Analyze Results
Form a Hypothesis
Draw a Conclusion
Set Up a Controlled Experiment
Publish Results
Record Results
Go to
Section:

11. 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.

12. Figure 1-8 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
Uncovered jars Covered jars
Controlled Variables:
jars, type of meat,
location, temperature,
time Several
days pass
Manipulated Variables:
gauze covering that
keeps flies away from
meat
Responding Variable:
whether maggots
appear Maggots appear No maggots appear
CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous
generation of maggots did not occur.

13. 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.

14. Figure 1-10 Spallanzani’s Experiment
Section 1-2
Gravy is boiled. Flask is Gravy is teeming
open. with microorganisms.
Gravy is boiled. Flask is Gravy is free of
sealed. microorganisms.

15. 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.

16. Figure 1-11 Pasteur’s Experiment
Section 1-2
Broth is boiled. Broth is free of Curved neck Broth is
microorganisms is removed. teeming with
for a year. microorganisms.

17. Figure 1-11 Pasteur’s Experiment
Section 1-2
Broth is boiled. Broth is free of Curved neck Broth is
microorganisms is removed. teeming with
for a year. microorganisms.

18. Figure 1-11 Pasteur’s Experiment
Section 1-2
Broth is boiled. Broth is free of Curved neck Broth is
microorganisms is removed. teeming with
for a year. microorganisms.

19. Figure 1-11 Pasteur’s Experiment
Section 1-2
Broth is boiled. Broth is free of Curved neck Broth is
microorganisms is removed. teeming with
for a year. microorganisms.

20. 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.

21. 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.

22. 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

23. 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.

24. 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.

25. 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.

26. 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

27. 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.

28. Characteristics of Living Things
Section 1-3
Characteristic Examples
Living things are made up of units called Many microorganisms consist of only a single cell.
cells. Animals and trees are multicellular.
Living things reproduce. Maple trees reproduce sexually. A hydra can
reproduce asexually by budding.
Living things are based on a universal Flies produce flies. Dogs produce dogs. Seeds from
genetic code. maple trees produce maple trees.
Living things grow and develop. Flies begin life as eggs, then become maggots, and
then become adult flies.
Living things obtain and use materials and Plants obtain their energy from sunlight. Animals
energy. obtain their energy from the food they eat.
Living things respond to their environment. Leaves and stems of plants grow toward light.
Living things maintain a stable internal Despite changes in the temperature of the
environment. environment, a robin maintains a constant body
temperature.
Taken as a group, living things change Plants that live in the desert survive because they have
over time. become adapted to the conditions of the desert.

29. 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.

30. Figure 1-21 Levels of Organization
Section 1-3
Biosphere The part of Earth
that contains all
ecosystems
Biosphere
Ecosystem Community and
its nonliving
surroundings
Hawk, snake, bison, prairie dog, grass, stream, rocks, air
Community Populations that
live together in a
defined area
Hawk, snake, bison, prairie dog, grass
Population Group of
organisms of one
type that live in
the same area
Bison herd
Go to
Section:

31. Figure 1-21 Levels of Organization continued
Section 1-3
Organism Individual living
thing
Bison
Tissues, organs,
Groups of and organ systems
Cells
Nervous tissue Brain Nervous system
Smallest functional
Cells unit of life
Nerve cell
Groups of atoms;
smallest unit of
Molecules most chemical
compounds Water DNA
Go to
Section: