Introduction to biology - Winston Knoll Collegiate
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Transcript Introduction to biology - Winston Knoll Collegiate
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
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 (cellstissuesorgansorgan systemsorganism)
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