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The Science of Biology
Biology 392
Observing the WorldObserving the World
If you are a thinker, you question things you observe and may not understand and you
try to find an answer. There are many ways to find these answers. If you are a scientific thinker you find your answer
using the scientific method.Example:
Why is the sky blue?
1-1 What is science?
an organized way of using evidence to learn about the natural world
It also refers to the body of knowledge that scientists have accumulated over time. It is not based on belief or faith, magic, or
legend but on actual evidence. It is concerned with the natural world, not the supernatural world.
What is Biology?
Biology is a specific field of science that studies
life
Important Skills used When Doing Science:
Observing- process of gathering information using your senses in a careful,
orderly way
Inferencing- making a logical interpretation based on prior knowledge or experience
Good Scientists... are skeptics: They question existing ideas and new hypotheses. are open-minded: They are always willing to consider new ideas
when evidence demands it rely on basic natural laws: They understand that the universe
functions as a system of interacting processes. repeat experiments: through an immense amount of research a
certain hypothesis might become so well-supported that scientists consider it a theory (example: biogenesis).
keep up with new knowledge gained through research: They continually revise and re-evaluate their ideas. NOTHING IS “FACT”.
*Many questions you have now or will have in the future involve science. You must understand science to make intelligent decisions about such issues.
How is Science Done? Scientists use the scientific method. When
scientists have a question about something in the world they use this method to find an answer:
State the Problem or Question Research State a hypothesis Design an experiment with a
control group, constants and variables Analyze data/ results Conclusion or Summary
1. State the Problem or Question
What have I observed?
What do I want to know?
2. Research
Has anyone asked this before?
Did they discover an answer?
How did they go about looking for an answer?
What other things do I need to understand to answer my question?
3. Form a Hypothesis
Based on the research you have done, write a possible answer or solution – your best
educated guess – to your question.
4. Design an Experiment Control Group: Part of your experiment that is
not varied in anyway. You can compare your test groups to this set standard group.
Independent variable- The change/difference you make in the experiment (the thing you are testing). Also called manipulated variable
Dependent variable- The differences that result from the experiment, the resulting effect. Also called responding variable.
Constants- Things in the experiment that do not change, kept exactly the same for each test group so they do not affect the results.
5. Data/Results
It is easier to understand the data if it is put into a table and/or graphed.
Make sure all data is clearly labeled. Charts and graph should always include units and titles.
When graphing the independent variable should be on the x axis and the dependent variable should be on the y axis.
6. Analysis
What happened?
What was expected? What was unexpected?
What trends did you notice in the data?
7. Conclusion or Summary
Indicate whether or not the data supports the hypothesis and explain why or why not.
Suggest possible improvements to the experiment.
Suggest further avenues of research or uses for the information discovered.
Learning Checkpoint What is inferencing? What are the steps of the scientific method? In which step would you find charts and graphs? What is the difference between an independent
variable and a dependent variable? What is the purpose of a control group? What does it mean to have a controlled experiment?
1-2 An Example of Science at Work
Observed: sometimes organisms just “arose” from nonliving things: eg. maggots came from meat.
The Question: How do new living things come into being? Hypothesis: In some cases, nonliving objects can spontaneously
generate living organisms.
1st Experiment- 1668, Francesco Redi: Meat in covered and uncovered jars proposed a new hypothesis: The maggots came from eggs left by flies
on the meat that were too small to see. Concluded: Maggots came from flies.
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 appear
Responding Variable: whether maggots appear
CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur.
Redi’s ExperimentRedi’s Experiment
Science continues...New Ideas with new discoveries
New discovery!- tiny microorganisms (discovered by Anton van Leeuwenhoek)
2nd Experiment- Mid 1700s, John Needham: Repeats Redi’s experiment. His hypothesis: Spontaneous generation can
occur under the right conditions. Result: microorganisms appear in sealed flask
of boiled gravy.
Science Experiments are always repeated:
3rd Experiment- Lazzaro Spallanzani: Thinks Needham did not boil gravy long enough to
kill existing microorganisms. Results: When left exposed to air, microorganisms
will appear in boiled gravy. He concluded that microorganisms could not come
from gravy but appeared instead from microorganisms existing in the air.
Spallanzani’s TestsSpallanzani’s Tests
Gravy is boiled. Flask isopen.
Gravy is teeming with microorganisms.
Gravy is boiled. Flask issealed.
Gravy is free of microorganisms.
Needham tried first but didn’t bring
gravy to hot enough temperature.
New Question: Is air the “life force”?
4th Experiment- 1864, Louis Pasteur: Set out to dismiss the notion that the “life
force”, air was needed to generate life. Used curved neck on flask so air could get
in but organisms would not. Concluded that all living things can only come from living things. This has been tested over and over and is now considered a theory called biogenesis.
Learning Checkpoint
Did all 4 scientists use good scientific thinking and a controlled experiment?
What is spontaneous generation? What was the point of the “swan neck”
Pasteur added to his flask? What is biogenesis?
1-3 Studying Life (Biology)
What is considered alive?
living things... are made of cells reproduce are based on a universal genetic code grow and develop obtain and use materials and energy respond to their environment Maintain a stable internal environment
(homeostasis) Change over time
Studying Life in Various Ways Branches of Biology
Divided into fields based on the type of life or particular perspective
Examples of type of life: Zoologist study animals, Botanist study plants, Microbiologists study bacteria and other small organisms
Examples of perspective: Paleontologists study ancient life, Embryologists study newly forming life
Studying Life at Various Levels
Bioethics
What is bioethics?Can you think of any ethical
issues that science must face?
1-4 Tools and Procedures used in Biology
Science ALWAYS uses the METRIC SYSTEM to make measurements
Why? Base units: Length- meter, Mass- gram, Volume-
liter, Temp. Celsius Conversions: 1 mile = _________m
1 pound= ________ kg
1 cup = ________ mL
Microscopes
Compound light microscope Series of lens that use light to magnify image (usually 1000x) can study dead or alive organisms, no smaller than .2 microns Have been used in conjunction with chemical stains (to identify
parts) and fluorescent dyes (to create 3-D images)
Electron microscope Use beams of electrons to produce images, up to 1000x more
detailed than light microscope images Cannot observe living specimens (slides must be in a vacuum) Two main types: SEM- scanning electron microscope and
TEM- transmission electron microscope
Learning Checkpoint What are the 8 characteristics of life? What is the difference between a community
and a population? What metric units would you use to measure
the amount of water in a pool?
Your height? Your weight? The weight of a paper clip?
The Microscope