1 the science of life. 2 biology – the study of life life arose more than 3.5 billion years ago...
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The Science of LifeThe Science of Life
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Biology – The Study of LifeBiology – The Study of Life
Life arose more than 3.5 billion years ago
First organisms (living things) were single celled
Only life on Earth for millions of years
Organisms changed over time (evolved)
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New organisms arose from older kinds ( millions of species)
Inhabit almost every region of Earth today
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Themes of BiologyThemes of Biology Cell structure and
function Stability and
homeostasis Reproduction and
inheritance Evolution Interdependence of
organisms Matter, energy, and
organization
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Cell Structure and Cell Structure and FunctionFunction
Cell basic unit of life All organisms are
made of and develop from cells
Some composed of only a single cell (unicellular) Virtually identical
to parent
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CellsCells Most composed of
many cells (multicellular) Cells are different
(undergo differentiation)
Cells are small Cells are highly
organized
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Cells contain specialized structures (organelles) that carry out the cell’s life processes
Many different kinds of cells
All cells surrounded by a membrane
Contain a set of instructions (genetic information)
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Stability and Stability and HomeostasisHomeostasis
Maintain very stable internal conditions
Temperature, water content, chemical content, etc.
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Reproduction and Reproduction and InheritanceInheritance
All organisms produce new organisms like themselves
Organisms transmit hereditary information to their offspring (reproduction)
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DNADNA Information in the form
of DNA (Deoxyribonucleic Acid)
DNA contains instructions for traits (genes)
Make the structures and complex chemicals necessary for life
DNA in every body cell (somatic) is exactly alike
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Sexual ReproductionSexual Reproduction
Hereditary information from two parts of same organism or two different organisms of the same species are combined
Egg and sperm zygote (fertilized egg)
Zygote contains hereditary information from both parents
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Asexual ReproductionAsexual Reproduction
Hereditary Hereditary information from information from different organisms different organisms is NOT combinedis NOT combined
Resulting cells Resulting cells contain contain identicalidentical hereditary hereditary informationinformation
Genetic information Genetic information from from single parentsingle parent
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EvolutionEvolution
Populations of organisms change (evolve) over generations (time)
Explains how many different kinds of organisms came into existence
Explains how modern organisms are related to past organisms
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Explains why organisms look and behave the way they do
Provides a basis for exploring the relationships among different groups of organisms
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Natural SelectionNatural Selection
Natural selection is the driving force in evolution
Organisms that have certain favorable traits are better able to successfully reproduce than organisms that lack these traits
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Natural SelectionNatural Selection
Survival of organisms with favorable traits cause a gradual change in populations over many generations
Known as “descent with modification”
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Interdependence of Interdependence of OrganismsOrganisms
Interaction of organisms with one another and with their environment (Ecology)
Single species – observing individuals of the species and their interactions with each other and their environment
Multiple species – large ecological studies of environments and communities (ecosystems)
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All organisms need substances such as nutrients, water, and gases from the environment
The stability of the environment depends on the healthy functioning of organisms in that environment
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Matter, Energy and Matter, Energy and OrganizationOrganization
Living things are highly organized Requires a constant supply of
energy to maintain their orderly state
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EnergyEnergy Almost all energy comes from the
sun (directly or indirectly) Photosynthesis is the process by
which some organisms capture the energy from the sun (solar) and transform it into energy (chemical) that can be used by living things
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AutotrophsAutotrophs Organisms that make
their own food are called autotrophsPhototrophs – use solar energy (photosynthesis) to get energy Convert H2O and CO2 into sugar and O2
Chemotrophs – use different chemical processes to get energy
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HeterotrophsHeterotrophs Organisms that must take in
food to meet their energy needs are called heterotrophs
Consume autotrophs (herbivores), other heterotrophs (carnivores) or both (omnivores) for their energy needs
Complex chemicals are broken down and reassembled into chemicals and structures needed by organisms
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The World of BiologyThe World of Biology
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Characteristics of LifeCharacteristics of Life
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Cells All living things are
composed of cells In multicellular
organisms many are specialized to perform specific functions
Cells are always very small
The size of multicelled organisms depends on the number of cells NOT their size
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Organization Organized at both the
molecular and cellular levels
Take in substances from the environment and organize them in complex ways
Specific cell structures (organelles) carry out particular functions
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In multicellular organisms, cells and groups of cells (tissues) are organized by their function Cells
tissues Tissues
organs Organs
systems
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Energy UseEnergy Use Use energy in a process called
metabolism Sum of all chemical processes
Require energy to maintain their molecular and cellular organization, grow and reproduce
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HomeostasisHomeostasis Maintain stable internal conditions
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GrowthGrowth Grow as the result of cell division
and cell enlargement Cell division is the formation of
two cells from a preexisting cell New cells enlarge as they mature
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The process by which an adult organism arise is called development Repeated cell divisions and cell
differentiation
DevelopmentDevelopment
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ReproductionReproduction All species have the ability to
reproduce and produce viable offspring. Not essential to survival of
individual but is essential for continuation of a species
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ResponsivenessResponsiveness Respond to stimuli in
the external environment
Detect and respond to changes in light, heat, sound and chemical and mechanical contact
Coordinates it’s responses
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EvolveEvolve Ability to adapt to their
environment through the process of evolution
Favorable characteristics are selected for and passed on to offspring
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Scientific MethodScientific Method
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ObservationObservation Employing your five senses to
perceive objects or events
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Asking a Question Based on observations; one or
more questions are generated
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HypothesizingHypothesizing Explanation for what you have
seen and recorded An educated guess Can be tested
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Forming a HypothesisForming a Hypothesis Statement is testable if evidence
can be collected that either does or doesn’t support it
Often must be revised if it is NOT supported by the testing data
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PredictingPredicting To test hypothesis it is necessary
to make predictions that logically follows from the hypothesis
A statement made in advance that states the results that will be obtained from testing the hypothesis
Often in the form of an “if-then” statement
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ExperimentingExperimenting
Testing a hypothesis or prediction by gathering data under controlled conditions – conducting a controlled experiment
Based on a comparison of a control group with an experimental group
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Both groups are identical except for one factor (independent variable)
Observations and measurements are taken for a particular factor (dependent variable) in both groupsDriven by or results from independent variable
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Collecting DataCollecting Data Includes any and
all information that scientist gather in trying to answer their questions
Includes all measurements & observations made during the experiment
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MeasuringInvolves quantitative data that can be measured in numbers
SamplingTechnique of using a sample – a small part – to represent the entire population
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Organizing DataOrganizing Data Involves placing observations and
measurement (data) in order Graphs, charts, tables, or maps
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Analyzing DataAnalyzing Data
Collected and organized data must be analyzed Process of determining whether
data are reliable or whether they support or do not support a hypothesis or prediction
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InferringInferring Conclusions made on the basis of
facts or premises rather than on direct observations Often drawn from data gathered
from a study or experiment and previous knowledge
Not directly testable
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Forming a TheoryForming a Theory A theory may be formed
after many related hypotheses have been tested and supported with experimental evidence
A broad and comprehensive statement of what is thought to be true
Supported by considerable evidence
Ties together related hypotheses
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CommunicationCommunication Share the results of
their studies with other scientists
Publish findings in journals or at scientific meetings
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CommunicationCommunication Sharing of information is
essential to scientific process Subject to examination and
verification by other scientists
Allows scientists to build on the work of others
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Microscopy and Microscopy and MeasurementMeasurement Microscopes – produce an enlarged
image of an object Used to study organisms, cells,
and cell parts Increase in apparent size is
called magnification The ability to show details
clearly is called resolution Microscopes vary in both
magnification and resolution
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Microscopes
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Light Microscopes Light Microscopes (compound)(compound) Specimen
mounted on a glass slide on stage
Must be thinly sliced or very small
Pair of lenses Ocular lens (eye
piece) – 10X Objective lens
(nose piece)
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Focusing a MicroscopeFocusing a Microscope On low power,
use the Coarse adjustment knob to focus
On high power, use the fine adjustment knob to focus
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Carrying and StorageCarrying and Storage Carry a microscope with one
hand on the arm & the other hand under the base
Store microscopes on low power, light off, slide removed, and covered
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Magnification determined by multiplying power of the ocular lens with the objective lens.
Low 4 x10=40Medium 10 x10=100High 40 x10=400
Maximum magnification is around 2000X for the best microscopes
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Electron MicroscopeElectron Microscope Transmission EM
Uses a beam of electrons to produce an enlarged image of very thinly sliced specimen on screen or photographic plate
Image focused by magnetic lenses
200,000X magnification Cannot be used to view
living specimens
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Scanning EMScanning EM 3D image Specimens not sliced
for viewing Surface sprayed with
fine metal coating Also uses electron
beam and fluorescent screen or photographic plates
100,000X magnification Cannot be used to view
living specimens
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Scientific Scientific MeasurementsMeasurements
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MeasurementsMeasurements Scientists use SI units or metric
system Based on units of ten
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Base Units of Measurement Length – Meter Volume – Liter Mass – Gram Time – Second Temperature - oC
Always read the Meniscus (bottom of the curve)
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Common Metric Prefixes Common Metric Prefixes used in Biologyused in Biology
Kilo- means 1000 Centi- means 1/100th
Milli- means 1/1000th
Micro – means 1/100,000th
Nano- means 1/100000000th
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Other Metric PrefixesOther Metric Prefixes
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