CHAPTER 1 – THE SCIENCE OF BIOLOGY
What Is Science?
(A) Organized way of using evidence to learn about
the natural world.
(B) Collection of knowledge that scientists have built
up after years of using this process.
Steps in the Scientific Method:
Step 1 – Observations – gathering data (information)
This can be Quantitative – expressed in #’s.
Or Qualitative – expressed other than #’s.
1. Inference – logical interpretation based on prior
knowledge or experience.
2. Inferences can lead to a hypothesis, or a scientific
explanation for a set of observations that can be tested in
ways that support or reject it.
Step 2 – Hypothesis (Prediction)
1. Proposed explanation for a set of observations.
2. Based on prior knowledge or imagination.
3. Represents a possible solution to a problem.
Step 3 – Test Hypothesis – with a controlled experiment.
1. When doing an experiment…
a. Test one variable at a time!!!!
(Variable – is something that causes the changes
observed in an experiment)
b. Have a controlled variable –the one that you don’t
change
c. Independent Variable– what you are changing
(manipulating)
d. Dependent Variable – the response to the change,
or outcome
Step 4 - Recording & Organizing Data – the more data the
better!
1. Tables; Graphs; Averages etc.
2. Can also be qualitative and/or quantitative.
Step 5 – Draw a Conclusion: use experimental data to support,
refute, or revise the hypothesis
Example of Famous Experiments: 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 Variable:
lid
Responding Variable:
Whether maggots appear
Maggots appear
Conclusion: Maggots form only when flies come in contact with meat.
Spontaneous Generation of maggots did not occur.
No maggots appear
Spallanzani’s Experiment
This experiment
showed that
microorganisms will
not grow in boiled and
sealed gravy that is
left open to the air.
Questions:
1. What variables were
controlled in this
experiment?
Flask is open
Gravy is boiled
Gravy is
teeming with
organisms
2. What variable is the
experimental (manipulated)
variable?
Flask is sealed
Gravy is free of
organisms.
Louis Pasteur’s Experiment
Broth is boiled
Broth is free of
organisms for a year.
Curved neck
is removed
Broth is
teeming with
microorganisms.
Questions: 1. Why did microorganisms not grow in the flask
before the neck was removed?
2. Why did the microorganisms grow after the neck was
removed?
Step 6 – Peer Review: Scientists share their work with
others. Scientists also try to duplicate the results to
confirm that the experiment was successful
Step 7 – Theories: well tested explanations that unifies a
broad range of observations.
1. Example: Theory of Evolution.
Law – Generalizes a body of observations. It explains
things, but does not describe them.
1. Example: Newton’s Laws,
Principle – a concept based on scientific laws (rules assumed
to be true)
1. Example: Bernoulli’s Principle (explains
aerodynamics)
What makes a good scientist?
– share scientific attitudes, or habits of mind, that
lead them to exploration and discovery.
– Are curious about what goes on around them
– are skeptics, which means that they question
existing ideas and hypotheses, and they refuse to
accept explanations without evidence.
– Are open-minded, meaning that they are willing to
accept different ideas that may not agree with their
hypothesis.
– Are creative
1-3 Studying Life
(A) Biology – Study of living organisms; study of the living
world.
(B) Biosphere – The part of the Earth that contains all
ecosystems
(C) Pg 21 record the levels of organization
Characteristics of Living Things.
1. Made of units called cells.
a. Unicellular – one-celled.
b. Multicellular – many celled.
2. Reproduction

Asexual – creates offspring by iteself, 1 parent

Sexual – creates offspring by sharing DNA, 2
parents
3. Based on a universal genetic code. (DNA)
4. Growth & development.
5. Obtain & use materials and energy.
– The combination of chemical reactions through which an
organism builds up or breaks down materials is called
metabolism.
6. Respond to their environment. (Respond to a stimuli)
7. Maintain a stable internal environment. (Homeostasis)
8. Taken as a group, living things change over time.
(Evolution)
–
Evidence of this shared history is found in all
aspects of living and fossil organisms, from physical
features to structures of proteins to sequences of
information in DNA.
Scientific Measurement:
Common Metric Units
Different Types of Microscopes
• Simple Microscopes – magnifying glass
(use 1 lens)
• Compound Microscopes – use more than 1
lens (ex. Light microscope that we use in
class)
• Electron Microscopes (SEM and TEM)
– Large, and expensive
Laboratory Techniques
• Cell Culture
• Cell Fractionation
– A single cell is grown
on a Petri dish,
reproduces, creating a
group of cells
– Can be used to test cell
responses
– Cells are put into a
blender and mixed
– Then they are placed in
a centrifuge
– The centrifuge spins
the cell parts and liquid
– The parts separate out
by their density