Biology: The Study of Life

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Biology The Study of Life

• An overview of semester 1

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Why Study Biology?

• To learn how organisms are constructed, how they
  function, where they live, and what they do
• To help you develop, modify, and refine your
  ideas about life
• Will cover characteristics of life NEXT WEEK

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The Methods of BiologySection 1.2

• The scientific method starts with observing
  inferring
• Whats the difference?
• Lets go through the scientific method

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The Scientific Method

• Observe Infer
• Identify your problem
• Hypothesize
• Controlled Experiment
• Have all the right parts of an experiment
• Variables, control groups, safety concerns, etc
• Collect analyze data
• Publish your results
• Verify your results by repetition
• Form a theory
• Develop a new hypothesis
• Revise the theory

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Role of Controlled Experiments

• Procedures used to study a phenomenon under known
  conditions
• Allows you to predict what will happen if a
  hypothesis is not wrong
• Can never prove a hypothesis 100 correct

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Controlled Experiment - Variables

• Independent Variable
• The condition in an experiment that is changed
  What you believe will cause the desired outcome
• Dependent Variable
• A condition that the scientist observes or
  measures b/c of the change in the independent
  variable

NOTE They are sometimes called different
names Independent manipulated,
explanatory, Dependent observed, resulting,
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Experimental Design

• VERY IMPORTANT!!!
• Conditions remain constant in both the test group
  and the control group
• The control group does NOT have the independent
  variable the experimental group DOES
• Control group
• A standard for comparison
• Identical to experimental group except for
  variable being studied

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Draw samples from some aspect of nature
CONTROL GROUP The variable being tested is absent
EXPERIMENTAL GROUP The variable being tested is
present
Compile results
Compile results
Compare and analyze the test results
Report on experimental design, test results, and
conclusions drawn from results
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You Try!

• Two agar plates (A and B) with 1,000
  streptococcus bacteria are incubated in identical
  10g nutrient medium at 37 C for 24 hours. Plate A
  has 10mg antibiotic X added, Plate B has a 10mg
  placebo added. After 24 hours, the number of
  bacteria remaining are counted.
• Control Group?
• Experimental Group?
• IV?
• DV?
• How are conditions controlled between the two
  groups?
• Hypothesis Grass will grow taller if fertilizer
  is added.
• IV Fertilizer
• DV Change in length of grass (metric)

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Data Collection Representation

• Crucial to keeping the experiment legitimate
• Qualitative vs. Quantitative data/research
• Uses a variety of methods
• Data Collection
• Drawings/sketches, instrument readings, note
  taking
• Data Representation
• Graphs, conclusions, etc

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GRAPHING - An Important Skill

• The 3 well use most are
• Line, Bar, Pie
• Whats the difference?

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Scientific Theory

• A hypothesis that has been tested for its
  predictive power many times and has not yet been
  found incorrect
• Has wide-ranging explanatory power
• Darwins Theory of Evolution by Natural Selection

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Scientific Method at Work

• Aristotle (384 322 BC) Proposed the theory of
  spontaneous generation
• Idea that living things can arise from nonliving
  matter
• Idea lasted almost 2000 years

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Disproving Spontaneous Generation
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Francisco Redis Hypothesis

• Rotten meat does not turn into flies. Only flies
  can make more flies.

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Redis Findings

• Jars w/ lid no flies, no maggots developed on
  the rotting meat within.
• Jars without lid flies on meat ? maggots soon
  were seen on the meat
• Conclusion Flies laying eggs, not dead rotting
  meat produce maggots
• New - Theory of Biogenesis

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The Scientific Method

• You might see it expressed different ways, but
  it is still the same process
• "If you want to increase your success rate,
  double your failure rate." Thomas Watson, Sr

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Limits of Science

• Scientific approach cannot provide answers to
  subjective questions
• Which color is best?
• Cannot provide moral, aesthetic, or philosophical
  standards
• -Can only use human perception
• technology

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The Nature of BiologySection 1.3

• Science Society
• Ethics Example Pharmaceutical Studies, animal
  testing, stem cell, genetic engineering

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Glowing Mice ethical?
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Asking Questions

• Scientists still ask questions that challenge
  widely held beliefs
• The external world, not internal conviction, is
  the testing ground for scientific beliefs