Introduction to
biology
Biology
Bios-: greek for life
-logy: study of
A biologist uses the scientific method to study living
things
Biology is the study of life
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Zoology
Botany
Microbiology
Ecology
Marine Biology
Genetics
Cell biology
Anatomy and physiology
Paleontology
So….What makes
something “living”?
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Made up of cells
Reproduce
Genetic code
Growth and development
Obtain and use materials (resources) and energy
Respond to their environment
Maintain a stable internal environment
As a group, they change over time
Made Up of Cells
• Cell
o Collection of living matter enclosed by a barrier
o Smallest structural unit of all living things
o Prokaryotic cells
• Cell without a nucleus, DNA is in cytoplasm
o Eukaryotic Cells
• Cell with a nucleus that contains the genetic material (DNA)
o Unicellular
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“uni-” means one
Organism that is made of one cell
Example: bacteria
Prokaryotic cells
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“multi-” means many
Contain hundreds, thousands, even trillions of cells
Many cells work together to make the living organism function
Cells vary in size, shape and function
Example: plants and animals
o Multi-cellular
Ability to Reproduce
• Asexual reproduction
o Organism has single parent
o Genetically identical to parent
o Splits in half
• Sexual reproduction
o Cells from two different parents unite to form new organism
o Increases genetic variety and survival of species
Based on a Genetic Code
• DNA nucleic acid that carries all the information
about the organism
• All living organisms have DNA, the “blue prints” of
life
Growth and
Development
• Growth means increase in
size, such as certain bacteria
• Development refers to cells
dividing to
o Includes periods of rapid growth and
dramatic change
o Sometimes different stages (think
caterpillar)
o During development, cells multiply and
are assigned specific functions and
roles within the multi-cellular
organism…DIFFERENTIATION
Obtain and Use materials
and Energy
• Obtain energy by taking in
resources
o Plants-sunlight
o Lizard-insects
• Metabolism
o Combination of chemical reactions
through which an organism builds up
or breaks down materials to carry
out life processes
Respond to their
Environment
• Stimulus
o A signal to which an organism responds
• External Stimuli
o From environment outside organism
o Example- water in soil stimulates germination
• Internal Stimuli
o Comes from inside an organisms body
o Low sugar levels in blood will stimulate you to feel
hungry
Maintain a Stable internal
environment
• Homeostasis
• When organisms maintain a stable internal
environment that is different from the external
environment
• Examples: shivering and sweating
As a group, they change over time
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Evolution
o Process of change
o When a group of organisms change over time
o Could occur over hundreds or millions of years
Adaptation
o An inherited trait that’s helps an organisms ability to
survive and reproduce in a particular environment
o Over a short period of time
Natural selection
o The most beneficial traits for a specific group of
organisms is passed on
o Organisms that have that specific trait will live longer
and produce more offspring than those who do not
have it
o The mechanism by which evolution occurs
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Levels of Organization
Molecular
o DNA/RNA and other molecules
Cellular
o Different cells
Groups of Cells
o (cellstissuesorgansorgan systemsorganism)
Organism
o A single species
Population
o A group of the same species
Community
o Many different groups of species and how they interact with
each other in a specific area
Ecosystem
o All the living and nonliving interactions in an area
Biosphere
o How all the different parts (biomes) of Earth come together
o Bio- means life
o Sphere- earth
o Life is found on land, in air, and in water
o “living Earth”
Life’s Diversity of Species
• Plants and animals…is there only one type?
• Species
o A distinct life form
o Biologists have identified more than one million
species
• There are various estimates to the actual
amount
o New species are discovered daily
o 5000 sp. of bacteria, 8600 sp. of birds, 30,000 sp.
of fishes, 100,000 sp. of fungi, 280,000 sp. of plants
and 1 million different species of….
• INSECTS
Domains
• Broadest category of classification
• Three main domains
o Domain Archea:
• unicellular prokary. That live in extreme environments (very hot or
very cold, extremely acidic or basic))
o Domain Bacteria: All other unicellular prokary.
o Domain Eukarya: Organism made up of eukary. Cells
• Includes 4 kingdoms: Protists, Fungi, Plants, Animals
Classification
• How do we organize all these species?
• We categorize all the different species in to broader
categories
• From broadest to most specific:
• Domain, Kingdom, Phylum, Class, Order, Family,
Genus, Species (Linnaean System of Classification)
• Binomial nomenclature
o BREAK UP THE WORD…
• BI-TWO, NOMIAL-NAME, NOMENCLATURE-NAMING SYSTEM
o This is how we identify a species
o The African lion is called Panthera leo
• What’s the genus?
o Panthera
• What is the species?
o Panthera leo (you say both genus and species)
Tools of Biology
Technology continually changes the way biologists work.
Imaging technologies provide new
views of life.
• A microscope provides an enlarged image of an object.
– light microscopes (LM)
stoma
Imaging technologies provide
new views of life.
• A microscope provides an enlarged image of an object.
– light microscopes (LM)
– scanning electron microscopes (SEM)
stoma
Imaging technologies provide new views of life.
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A microscope provides an enlarged image of an object.
– light microscopes (LM)
– scanning electron microscopes (SEM)
o transmission electron microscopes (TEM)
stoma
• Imaging technology is used in medicine.
– X-ray images
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Imaging technology is used in medicine.
– X-ray images
o magnetic resonance
imaging (MRI)
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Imaging technology is used in medicine.
– X-ray images
– magnetic resonance
imaging (MRI)
o functional MRI (fMRI)
Complex systems are modeled on
computers.
• Computer models are used
to study systems that
cannot be studied directly.
Normal heartbeat
o heart attacks
– effect of medicines on the human
body
– movement of water molecules into and out
of a cell
– spread of a disease through a population
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Computer models are used when experiments
are not safe, ethical, or practical.
Heart attack
The tools of molecular genetics give rise to new biological
studies.
• A gene is a segment of DNA that stores genetic
information.
• Through our understanding of DNA, we can study
genetics on a molecular level.
– molecular genetics
– genomics
SCIENTIFIC
METHOD
Review
Scientific Method
• Organized problem solving
• Not a single method
Steps of the Scientific
Method
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Define the Problem
Collect Information About the Problem
Form a Hypothesis
Experiment
Collect Results
Conclusion
Repeat
Step 1. Problem
• What are to trying to find out?
- Usually based on observations
- stated as a question
Example: I notice that on warm nights crickets seem
to chirp more often
Problem =
Does temperature affect the rate of
cricket chirps?
Step 2. Collect Information
About the Problem
• Information can be gathered from:
- your own observations
- published research
textbooks, articles, internet etc…
Step 3. Form a Hypothesis
• A possible solution to your problem
• Must make a prediction
• Must be possible to be disproved
- UFOs exist is not a scientific hypothesis because it is
impossible to disprove
Formal Hypothesis
• A formal hypothesis used in an experiment should
be stated in If…Then form.
- It relates directly to the experiment to be
conducted and explains the expected outcome
-If I do this…..then that will happen.
Example: If I raise the temperature I keep
crickets in, then they will chirp more.
Step 4. Test Your
Hypothesis-Experiment
 Experiment must be controlled
- tests only one thing at a time
• A controlled experiment compares a control group
with an experimental group
 The control group provides a normal standard against
which the biologist can compare results of the
experimental group.
 The experimental group is identical to the control
group except for the one factor being tested
- the variable being tested is the independent
variable
Experimental Design
• Needs to be repeatable
• Should test a large sample
• Should be without bias
Variables
• Variable = anything that can change in an
experiment
• Controlled variables = What do I keep the same?
• Independent variables = What do I change?
aka Manipulated variables
• Dependent variables = What do I measure?
aka Responding variables
Cricket Experiment
Control Group
Experimental Group
• 20 crickets grown in
a 10 gallon
aquarium
• 12 hours of light/day
• Fed 5 g Acme
Cricket Food
• Kept at 25°C
• 20 crickets grown in
a 10gallon
aquarium
• 12 hours of light/day
• Fed 5 g Acme
Cricket Food
• Kept at 30°C
Step 5 Data and Results
Data = observations or measurements
- Quantitative = number data
10 chirps/minute
- Qualitative = observations
color changed to orange
Results = Processed data – makes the meaning of
the data more clear.
Allows you to see trends or patterns. Calculate an
average, graph of data etc..
Graphing Your Data
• Independent Variable- the factor that is changed
before the experiment begins. It goes on the x-axis.
Sometimes called manipulated
• Dependent Variable- the factor that you ran the
experiment to measure, sometimes called results. It
goes on the y-axis. Sometimes called responding
Sample Graph
Dependent Variable: on
the Y Axis
Independent Variable on the X Axis
Conclusions
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Was your hypothesis correct?
- do the results support your hypothesis
What are possible sources of error?
What next? – What question could you study next?
Why is this important?
Repeat Your
Work/Publish
• Repeat experiment to confirm your results.
• When scientists have completed their
work, they publish their results
- this informs other scientists of their
findings
Theory
• A hypothesis that has been tested repeatedly and
shown to be correct becomes a theory
• Theories can explain current observations and
predicts new observations
• A theory is as close to certainty as you get in
science
Vocabulary to Know and Love
 HYPOTHESIS
 EXPERIMENTAL GROUP
 CONTROL GROUP
 VARIABLE
 CONTROLLED VARIABLES
 INDEPENDENT/MANIPULATED VARIABLE
 DEPENDENT/RESPONDING VARIABLE
 DATA
 QUANTITATIVE DATA
 QUALITATIVE DATA
 RESULTS
 THEORY