Biology

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Biology

• Ch 1 The Science of Life

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Ch 1 The Science of Life

• 1-1 The World of Biology
• 1-2 Themes in Biology
• 1-3 The Study of Biology
• 1-4 Tools and Techniques

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Section 1-1 The World of Biology

• Relate the relevance of biology to a persons
  daily life.
• Describe the importance of biology in human
  society.
• List the characteristics of living things.
• Summarize the hierarchy of organization within
  complex multicellular organisms.
• Distinguish between homeostasis and metabolism
  and between growth, development, and reproduction.

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Biology and You

• Biology the study of all living things
• Biology Involves
• Microscopic structure of single cells
• Global interactions of millions of organisms
• Life history of individuals
• Collective histories of groups of organisms

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• Biology can be used to both solve societal
  problems and explain aspects of our daily lives.
• Improving food supply
• Staying healthy
• Curing disease
• New tools and technology
• Preserving our environment

Branches of Biology Animation
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Characteristics of Life

• Organization and Cells
• Response to Stimuli
• Homeostasis
• Metabolism
• Growth and Development
• Reproduction
• Evolution

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Organization and Cells

• Organization the high degree of order within an
  organisms internal and external parts and its
  interactions with the living world
• Organisms of the same species have the same body
  parts arranged in nearly the same way and
  interact with the environment in the same way.
• All living organisms have some degree of
  organization.

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• Cell the smallest unit that can perform all
  lifes processes
• All living things are composed of cells.
• Unicellular made of one cell (ex. Bacteria)
• Multicellular made of many cells (ex. A tree)
• In multicellular organisms, some cells are
  specialized to play a specific role.

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Levels of Organization (text p6-7)

• Organism a living thing
• Organ System groups of specialized parts that
  carry out a certain function in the organism.
• Organs structures that carry out specialized
  jobs within an organ system.
• Tissues groups of cells that have similar
  abilities and that allow the organ to function

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• Cells must be covered by a membrane, contain all
  genetic information necessary for replication, be
  able to carry out all cell functions.
• Organelles tiny structures that carry out
  functions necessary for the cell to stay alive.
• Biological molecules chemical compounds that
  provide physical structure and bring about
  movement, energy use, and other cellular
  functions
• Atoms the simplest particle of an element that
  retains all the properties of a certain element.

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Response to Stimuli

• Stimulus a physical or chemical change in
  internal or external environment
• Ex a owls eye dilates/contracts to keep levels
  of light entering the eye constant

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Homeostasis

• The maintenance of a stable level of internal
  conditions even though environmental conditions
  are constantly changing.
• Regulatory systems maintain stable levels for
  temperature, water content, uptake of nutrients,
  etc.
• Ex. To maintain body temp. owls can burn fuel to
  produce body heat and fluff feathers for
  insulation

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An example of a mechanism of homeostasis.
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Metabolism

• Metabolism the sum of all the chemical reactions
  that take in and transform energy and materials
  from the environment
• Organisms need energy to maintain molecular and
  cellular organization, growth, reproduction.

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Growth and Development

• Growth
• Living things grow as a result of cell division
  and cell enlargement.(unicellularcell
  enlargement multicellularboth)
• Cell division the formation of two cells from an
  existing cell.
• Development the process by which an organism
  becomes a mature adult.
• Involves cell division, cell differentiation/
  specialization

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Reproduction

• All organisms produce new organisms like
  themselves
• Not essential to the survival of individual
  organisms, but is essential to the continuation
  of a species.
• Organisms transmit hereditary information to
  their offspring (DNA deoxyribonucleic acid)
• DNA makes up genes which contain the instructions
  for making all the structures and chemicals
  necessary for life.

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Click to animate

• Sexual Reproduction 2 parents. Offspring carry
  traits of both parents and is similar but not
  identical to parents. (ex. Frogs)
• Asexual Reproduction 1 parent. Offspring
  identical to parent. (ex. Bacteria)

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Evolution

• Populations of living organisms evolve or change
  through time.
• Important for survival in a changing world.
• Explains the diversity of life-forms we see on
  Earth today.

Evolution by Natural Selection Animation
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1-2 Themes in Biology

• Identify three important themes that help explain
  the living world.
• Explain how life can be diverse, yet unified.
• Describe how living organisms are interdependent.
• Summarize why evolution is an important theme in
  biology.

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Themes in Biology

• Diversity and Unity of Life
• Interdependence of Organisms
• Evolution of Life

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Diversity and Unity of Life

• Diversity variety
• Bacteria that live in Arctic ice
• Whales made of 1,000 trillion cells
• Plants that capture and digest insects
• Biologists have identified more than 1.5 million
  species on Earth, but many more remain to be
  identified.

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• Unity features that all living things have in
  common.
• The genetic code the rules that govern how cells
  use the heredity information in DNA
• Presence of organelles that that carry out all
  cellular activities.

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• The Tree of Life a model of the relationships by
  ancestry among organisms
• All living things share certain genes, yet no two
  types of organisms have the same full set of
  genes.
• Organisms that have more similar sets of genes
  are on closer branches or lineages. More
  distantly related organisms are farther apart.

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This Tree of Life is a model of the relationships
by ancestry among all major groups of organisms.
The model is based on comparisons of organisms
characteristics, including body structures and
genetic information.
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• Scientists think that all living things have
  descended with modification from a single common
  ancestor. All of life is connected.
• The many different lineages representing
  different species stems from the fact that
  genetic changes accumulate over the years.
  Organisms change or evolve through natural
  selection as they become better suited to their
  own special environments.

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• Three Domains of Life
• Domains major subdivisions of all organisms.
  Bacteria, Archaea, Eukarya
• The Six Kingdoms of Life
• Another system for grouping organisms
• Animalia, Plantae, Fungi, Protista, Archaea,
  Bacteria

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Interdependence of Organisms

• Ecology the branch of biology that studies
  organisms interacting with each other and with
  the environment
• Ecosystems communities of living species and
  their physical environments. Organisms depend on
  each other as well as on minerals, nutrients,
  gases, heat, and other elements of their physical
  surroundings.

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• Scientists now recognize the huge effect that
  humans have had on the worlds environment. (ex.
  Deforestation, Greenhouse Effect, Ozone
  Depletion, Soil Erosion, etc.)

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Evolution of Life

• Individual organisms change during their
  lifetime, but their basic genetic characteristics
  do not change.
• Evolution descent with modification.
• Process in which the inherited characteristics
  within populations change over generations such
  that genetically distinct populations and new
  species can develop.

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• The theory of evolution helps us understand
• How the many kinds of organisms that have lived
  on Earth came into existence.
• How organisms alive today are related to those
  that lived in the past.
• Basis for explaining the relationship among
  different groups of organisms.

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Evolution by Natural Selection

• Organisms that have certain favorable traits are
  better able to successfully reproduce than
  organisms that lack these traits.
• Adaptations are favorable traits produced through
  natural selection
• Driven in part by competition among individuals
  for resources necessary for survival, such as
  food.
• The survival of organisms with favorable traits
  causes a gradual change in populations of
  organisms over many generations. Descent with
  modification is responsible for the multitude of
  life-forms we see today.

Animation for Evolution by Natural Selection
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1-3 The Study of Biology

• Outline the main steps in the scientific method.
• Summarize how observations are used to form
  hypotheses.
• List elements of a controlled experiment.
• Describe how scientists use data to draw
  conclusions.
• Compare a scientific hypothesis and a scientific
  theory.
• State how communication in science helps prevent
  dishonesty and bias.

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Science as a Process

• Methods of science are based on two principles
• Events in the natural world have natural causes.
• Uniformity the idea that the fundamental laws of
  nature operate the same way at all places and at
  all times.

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Steps of the Scientific Method
Animation

• Observation the act of perceiving a natural
  occurrence that causes someone to pose a
  question.
• Hypothesis a proposed explanation for the way a
  particular aspect of the natural world functions.
  
• Good hypotheses answer a question and are
  testable.
• Prediction a statement that forecasts what would
  happen in a test situation if the hypothesis were
  true.

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• Experiment used to test a hypothesis and its
  predictions.
• Data is analyzed and are used to draw conclusion.
• Communication of data and conclusion to
  scientific peers and the public. Others can
  verify, reject, or modify the researchers
  conclusions.

See text p14-15
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Designing an Experiment

• Controlled Experiment compares an experimental
  group and a control group while testing only one
  variable.
• Control Group provides a normal standard against
  which biologists can compare the results of the
  experimental group.
• Experimental Group differs from the control
  group by only one factor (independent variable)

Controlled Experiment Animation
Another Controlled Experiment Animation
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• Independent variable / manipulated variable
  variable that differs between the control group
  and the experimental group. The factor that is
  being tested and is manipulated by the
  experimenter.
• Dependent variable /responding variable the
  factor that is driven by or results from the
  independent variable. The changes you observe
  during the experiment.

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• Blind Experiments the biologist who scores the
  results is unaware of whether a given subject is
  part of the experimental or control group. Helps
  eliminate experimental bias.
• Experiments should be repeated because living
  systems are variable.
• Scientists must collect enough data to find
  meaningful results.

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Data Collection

• Data is collected through observation and
  measurement.
• Scientists use tools to extend their senses (ex.
  Microscope, microphone, infrared camera)
• Most experiments measure the dependent variable.

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Types of Data

• Quantitative data data that can be measured in
  numbers. Can be compared by scientists repeating
  others experiments.
• Qualitative data data that includes observations
  and descriptions that do not involve numbers.

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• Sampling the technique of using a sample or
  small part to represent a whole or entire
  population. To be useful, samples must be large
  and random.

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• Organizing Data involves placing observations
  and measurements in some kind of logical order
  graph, chart, table, map

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Analyzing Data

• To determine whether data are reliable and
  whether they support or fail to support the
  predictions of the hypothesis.
• Use statistics to help determine the relationship
  between the variables involved.
• Compare data with other data that were obtained
  in other similar studies.
• Determine possible sources of error.

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Drawing Conclusions

• An experiment can only disprove, not prove, a
  hypothesis.
• Acceptance of a hypothesis is always tentative in
  science. Can revise understanding based on new
  data.

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• Inference a conclusion made on the basis of
  facts and previous knowledge rather than on
  direct observation. Not directly testable.
• May apply findings to solve practical problems or
  build models to represent or describe things
  (physical model, mathematical equation.)

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Theory

• When a set of related hypotheses is confirmed to
  be true many times and can explain a great amount
  of data. (ex. Cell theory, theory of evolution by
  natural selection)
• Non-scientific theory an untested idea, guess.

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Communicating Ideas

• Scientists often work together in research teams.
• Share research results with other scientists
  through scientific journals or presenting at
  scientific meetings.
• Allows others working independently to verify
  findings or to continue work on established
  results.

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Publishing a Paper in a Scientific Journal

• 4 sections
• Introduction (problem and hypothesis)
• Materials and Methods
• Results
• Discussion (gives significance of experiment and
  future direction the scientist will take)

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• Peer Review Scientists who are experts in the
  field anonymously read and critique the research
  paper.
• Checks for enough info so experiment can be
  duplicated, good experimental design, accurate
  conclusion, and clearly written.
• Prevents dishonesty.

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Honesty and Bias

• Must be careful to prevent previous ideas and
  biases from tainting both experimental process
  and the conclusion
• Scientist may wish for their hypothesis to be
  supported
• Experiments are repeated to verify previous
  findings.
• Avoid conflict of interest. (ex. Owning a
  biotechnology company and being in charge of
  testing drug safety and effectiveness.)
• The threat of a potential scandal based on
  misleading data or conclusions is a powerful
  force in science that helps keep scientists
  honest and fair.

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Section 1-4 Tools and Techniques

• List the function of each of the major parts of a
  compound light microscope.
• Compare two kinds of electron microscopes.
• Describe the importance of having the SI system
  of measurement.
• State some examples of good laboratory practice.

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Microscopes

• An instrument that produces an enlarged image of
  an object. Shows details
• Used to study organisms, cells, and cell parts
  that are too small to otherwise be seen.
• Magnification increase of an objects apparent
  size.
• Resolution the power to show details clearly.

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Types of Microscopes

• Compound Light Microscope
• Electron Microscope

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Compound Light Microscope(LM)

• The image of a transparent specimen is enlarged
  as it passes through the objective and ocular
  lenses.
• Specimen is mounted on a glass slide
• Specimen must be sliced thin enough to be
  transparent or must be very small.

Also see p.1070-1071
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Compound Light Microscope(LM)
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Compound Light Microscope (LM) - continued

• The set of objective lenses have different powers
  of magnification.
• Power of magnification
• Factor of enlargement. Objective x ocular total
  power of magnification.
• Resolution of LM is limited by the physical
  characteristics of light. Blurry beyond about
  2000x.
• As power of magnification increases, resolution
  drops.

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Light Microscope Images

• Elodea

• Amoeba eating algal cells

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Light Microscope Images

• Human Lice
• Euglena

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Electron Microscope

• View specimens smaller than cells cell parts,
  viruses, bacteria
• A beam of electrons rather than a beam of light
  produces an enlarged image of the specimen
• Types of Electron Microscopes
• Transmission Electron Microscope (TEM)
• Scanning Electron Microscope (SEM)

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Transmission Electron Microscope (TEM)

• Transmits beam through a very thinly sliced
  specimen.
• Magnetic lenses enlarge the image and focus it on
  a screen or photographic plate.
• Up to 200,000x.
• Cannot be used to view living specimens.

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Transmission Electron Microscope (TEM)
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TEM images

• Salmonella bacteria

• Corona virus particles

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TEM images

• HIV infection in lymph tissue 27,630X

• Red blood cell in a capillary 5,370X

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Scanning Electron Microscope (SEM)

• 3-D images
• Up to 100,000x.
• No live specimens. Specimen sprayed with fine
  metal coating
• Beam of electrons passed over surface causing
  metal to emit a shower of electrons projected
  onto a fluorescent screen or photographic plate
  producing image of object.

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Scanning Electron Microscope (SEM)
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SEM images

• Black Widow Spider Claw 500X

• Radiolarian 750X

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SEM images

• Mosquito head 200X

• Mosquito head 1000X

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SEM images Dennis Kunkel Microscopy, Inc.

• Deer Tick

• Surface of blade of grass

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Object Size and Magnifying Power of Microscopes
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Measurement

• International System of measurements (SI)
• System International dUnites
• Single standard of measurement used by all
  scientists
• Seven Base Units Table 1-1 p23 

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SI Base Units
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Multiples of base units

• Multiples of a base unit (in powers of 10) are
  designated by prefixes.
• Table 1-2 p23.
• They are used to find appropriately sized unit
  for a particular measurement.

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Some SI Prefixes
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Derived Units

• Produced by the mathematical relationship between
  two base units or between two derived units.
  Table 1-3 p23

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SI Derived Units Used in Biology
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Other units

• Some units of measurement are not part of SI but
  are commonly used with SI. Table 1-4 p23

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Other Units Acceptable for Use with SI
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Safety

• Hazards can be chemical, physical, radiological,
  or biological.
• Good Laboratory Practice establishing safe,
  common-sense habits
• Never work alone in the lab or without proper
  supervision by the teacher.
• Always ask your teacher before using any
  equipment.
• Protect yourself and review safety alerts.
  (Figure 1-15 p24, p1066-1069)

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• Holt Resources Practice Quiz

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