Download Scientific Method

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Introduction to Biology
What is Science?
Goal of science is to
understand the world around us.
What is Biology?
Study of life. There are MAY branches!
Biology is related to other sciences …
Chemistry, physics, math ...
Eric Steven Lander, a mathematician, worked with
the Human Genome Project. He could more easily
analyze statistically whether a disease may be caused by
1 or many genes!
Why Study Biology?
Scientific Method
• We need to understand in order to make
healthy decisions in life.
Step 1: Observe and State the Problem.
• Knowledge is power.
Step 3: Test the hypothesis by Investigation or
Experimentation.
• We are all connected!
Example: Rainforest.
• Science and Human Values
Example: Cloning, Stem cell research
Step 2: Form a Hypothesis.
Step 4: Record and Analyze Data.
Step 5: Form a Conclusion.
Step 6: Replicate the Work (Verification).
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What does
A hypothesis is a probable solution or
an educated (scientific) guess based on
what you have read and observed.
“OBSERVE”
mean?
Experiment
Control Group – used to show that the result of an
experiment is really due to the condition you are testing.
Experimental Group –
identical to the control
except for the independent variable.
Constant – a factor that does
not change throughout an
experiment (ex) amount of light,
water, and heat
Experiment
Independent Variable
factor adjusted by the
experimenter.
(ex) amount of fertilizer
Dependent Variable
results from the action of the
independent variable.
(ex) amount of plant growth
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Record and analyze Data = information gathered by
observation or investigation.
Data can be collected by weighing, measuring, cutting
apart, looking at etc.
Form a Conclusion – statement about
the original hypothesis based on all the
information that has been gathered.
Replicate the Work …
Verification use of many experiments
to test a single hypothesis
- - - to become more
sure about the conclusion.
REMEMBER
The sharing of information
among scientists is critical!
Once scientists have collected data from many
experiments and find that the data consistently
supports their hypothesis, the hypothesis may then
become a scientific law or theory.
Scientific Law – a “rule of nature”
that describes the behavior of
something in nature.
Theory – explains why things
happen the way they do.
ALWAYS KEEP AN OPEN MIND. Theories and
laws can be changed!!!
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Tools/Technique
s
of a Biologist
Cell apoptosis
Compound light microscope
Transmission Electron Microscope (TEM)
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Surface of eyeglasses
Ant holding a microchip
Scanning Electron Microscope (SEM)
Scanning Probe Microscope
Centrifugation
Micromanipulation
and Microinjection
used to separate a sample into its component parts.
Centrifugation is also used to separate cell parts Cell Fractionation
Special tools
(so small/looking
through a
microscope) are
used to insert,
remove, dissect or
otherwise
manipulate certain
parts of cell.
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Sperm cell
Ovum
Intracytoplasmic sperm injection (ICSI )
Enucleation (Cloning)
Cell Cultures
Characteristics of Living Things
1. All living things are made up of CELLS.
Whitefish blastula cells
Onion cells
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There are unicellular organisms
… and there are multicellular organisms.
TREE
AMOEBA
2. All living things are highly organized at
both the molecular and cellular levels.
Giraffe
CELL SPECIALIZATIO
Blood cells
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Nerve Cells
A human egg surrounded by sperm - one of which will fertilize it!
3. All living things obtain and use energy.
Chloroplast
Mitochondria
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4. All living things respond to their environment.
H
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M
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O
S
T
A
S
I
S
5. All living things grow and develop.
I’m
Irritable!
Adult
organism
What is
the
stimulus
in this
case?
6. All species of organisms reproduce.
early all plants are able to reproduce asexually.
Strawberries and spider plants send out
“runners” which
root (and form a
new plant) when
they touch ground.
Asexual
reproduction
Yeast cell - budding
Willow branches
are notorious for
rooting when they
fall on very wet
soil.
Spider plant
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Fragmentation - separation of the original
body into segments, sometimes specialized, which
grow into new individuals.
Parthenogenesis - egg develops without
fertilization.
A familiar example is the
Aphids
aphid, which may reproduce
by parthenogenesis for much
of the year, producing only
females.
Common in plants and flatworms.
Planaria
Moss
Sexual
reproduction
Males are produced before
winter, and the sexually
produced eggs have hard shells that can
withstand the rigors of winter weather.
Fungus
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Paramecia
reproducing
sexually
Prokaryotic cells (bacteria) reproduce by binary fission;
a process in which the genetic material of the cell is copied
and then the parent cell divides.
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