Exploring Life Chapter 1

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Exploring LifeChapter 1

• General Biology Science Majors I 1406

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What is Biology?

• Biology is the science of life and of living
  organisms, including their structure, function,
  growth, origin, evolution, and distribution.

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Unifying Themes

• Three Major Groups
• Exploring Life on Its Many Levels
• Evolution, Unity, and Diversity
• The Process of Science

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1. Exploring Life on Its Many Levels

• Hierarchy of Biological Organization

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2. Emergent Properties of Life

• Reproduction
• All organisms are capable of reproducing and
  passing their genetic material to their
  offspring.
• Organisms reproduce only their own kind.
• Life comes only from life.

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Emergent Properties of Life

• Growth and Development
• All organisms are capable of growing.
• DNA directs the pattern of growth and development
  of an organism.

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Emergent Properties of Life

• Utilization of Energy
• All organisms use energy and transform it in
  order to do work.
• Ex Plants take in energy from the sun and
  transform it into chemical energy.
• Ex Bat gets its energy from the nectar from the
  saguaro cactus, and use it to fly and carry out
  its nocturnal activities.

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Emergent Properties of Life

• Homeostasis
• Organisms maintain relatively constant internal
  conditions different to their environment through
  regulatory mechanisms
• The blood vessels of the jackrabbit regulate the
  loss of heat to its environment.

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Emergent Properties of Life

• Evolutionary Adaptation
• Organisms adapt to their environment.
• This white-tailed ptarmigan has evolved white
  plumage and it is almost invisible against the
  snow. This adaptation protects it from
  predators.

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Cells the Basic Units of Structure Function

• The Cell Theory
• Three Basic Principles
• All organisms are made up of one or more cells
• Cells are the smallest unit of life
• Cells come from preexisting cells

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Two Types of Cells

• Prokaryotic Cells
• Bacteria
• Archaea bacteria
• Eukaryotic Cells
• All other organisms are composed of eukaryotic
  cells
• protists
• fungi
• plants
• animals

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Continuity of Life DNA

• DNA
• DNA (Deoxyribunucleic Acid) is the hereditary
  blueprint in each cell of all living organisms.
• Double helix
• The two strands are held together by a base
  pairing.
• Biological instructions are encoded in the DNA
• DNA carries the units of inheritance that
  transmit information from parents to offspring.

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Structure and Function

• Structure and function are correlated at all
  levels of biological organization.
• Birds have hollow bones which provide a strong
  lightweight skeleton.

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Organisms Interact with their Environment

• Organisms are open systems that exchange
  materials and energy with its surroundings.

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Regulatory Mechanisms

• Many biological processes are self regulating.
  They operate by a mechanism called feedback.
• The product of the process regulates the process.
  
• Two kinds of feedback
• Positive feedback speeds up the process
• Negative feedback slows down or stops the process

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The Kingdoms of Life(Carl Woese, University of
Illinois)

• Common Ancestor
• Bacteria Archaea Eukarya (3
  Domains)
• Eubacteria Archaebacteria
  Protista Plantae Fungi Animalia

(Ref Life the Science of Biology, 5th Edition,
1998)
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3. How do we do Science?

• Scientific Methodology
• observations and make generalizations
• generate a question (s)
• generate a hypothesis (tentative statement about
  the natural world)
• formulate a testable prediction
• design an experiment to test the prediction
• if statistical analysis shows significant
  difference between the control group and the
  experimental group, your hypothesis is accepted,
  otherwise it is rejected
• if rejected, then modify the hypothesis and
  repeat steps 3 and 4

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What is a Hypothesis?

• Commonly
• A hypothesis is an idea of how things work.
• Formally
• A hypothesis is a tentative answer to some
  question.

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How do we test a hypothesis?

• Hypothesis testing is based on deductive
  reasoning.
• Deductive reasoning involves making a specific
  prediction about the outcome of an action and is
  based on observable facts.
• Thus, deductive reasoning takes the if/then
  statements.

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How Do We Test a Hypothesis?

• We test the hypothesis by performing the
  experiment to see whether or not the results are
  as predicted.

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Experimental Method

• Experiments are designed to test hypotheses.
• Controlled Experiments
• Control Group data from a control group are
  used as baseline values for comparison to the
  measurements of the experimental group.
• Experimental Group data from the experimental
  group are compared against the control group and
  determine whether the hypothesis being tested is
  accepted or rejected.
• Example of an unbiased experimental design
• Double-blind experiments

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Double-Blind Experiments

• Results from double-blind experiments produce
  more objective data.

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Analysis of the Data

• The data that is collected from an experiment
  must be statistically analyzed.
• Statistically significant results indicate that
  there is a 5 probability or less that the
  results may be due to chance alone.
• Types of statistical analysis include
• Correlation between two variables
• Analysis of Variance
• t-test
• Multivariate tests
• If the results of the statistical analysis do not
  support the hypothesis, then the hypothesis is
  rejected.

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Evaluating Scientific Information

• Primary Sources
• New findings are published in scientific journals
  for peer review.
• A group of scientists (peers) scrutinize the
  article before they approve it for publication
• Scientific journals contain the most recent and
  accurate scientific information.
• After a hypothesis has been tested extensively
  and the results support the hypothesis then the
  hypothesis becomes a theory.
• A theory is the highest degree that a hypothesis
  can ever achieve.
• Ex. Theory of Evolution by Charles Darwin
  provides a good example of how scientific theory
  grows and wins acceptance.

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Critical Thinking

• Skepticism questionable attitude
• what are the credentials of the individual making
  the statement?
• is there verifiable evidence to support the
  statement?
• is there a political or monetary incentive behind
  the statement?
• Most scientists are skeptical about radical
  findings
• Ex. Stomach ulcers
• The scientist who discovered that most stomach
  ulcers are caused by Heliobacter pylori bacteria
  encountered much ridicule from the scientific
  world because stomach ulcers were believed to be
  caused by stress.

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Critical Thinking

• The validity of a statement is supported by sound
  statistical analysis.
• Beware of the claims made by nonscientists and
  even by some scientists.
• If the claim states something like scientific
  research proved that be very careful because
• Scientific studies NEVER EVER prove anything.
• Scientists conduct research to test a
  hypothesis, to disprove a hypothesis.

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Are there any limitations to science?

• Is science limited? YES !!!
• Science is based on testable facts.
• Science cannot be applied to
• religious beliefs because they are based on faith
  
• faith cannot be tested
• morals, value judgments, social issues,
  attitudes, love, or supernatural forces

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Science is Self-Correcting

• Science is limited by the ability of the
  scientists to collect data and interpret data.
• New advances in technology have made it possible
  for science to correct misinterpreted data. New
  interpretation replaces the old incorrect
  information.
• Example
• belief that the earth was merely 6000 years old.
• belief that the sun revolved around the earth.