Ch. 1: The Nature of Science

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Ch. 1 The Nature of Science

• Honors Biology

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The World of Biology

• Biology the study of life
• Organized and scientific framework for answering
  questions about living things
• How do living things work?
• Why do they work this way? Why do they take the
  forms that they do?
• How do they interact with their environment?
• How do they interact with each other?

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Thinking about the Nature of Science

• What is science?
• What makes science powerful?
• What characteristics must something have in order
  for it to be science?
• How does one do science?

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What is Science?

• Science is an organized, evidence-based method of
  learning about the natural, material world.
• Skills Used By Scientists
• Observation scientists use their senses (sight,
  hearing, touch, smell, and sometimes taste) to
  observe nature
• Hypothesizing and Predicting scientists attempt
  to explain the observations by forming
  hypotheses, and form predictions to test these
  hypotheses
• Analyzing and Interpreting scientists analyze
  and interpret data collected during experiments
  while using prior knowledge and experience

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The Scientific Method

• Tell me about the scientific method!
• Now, is the scientific method universal to
  science? Must all scientific investigations
  follow this method?
• Can anyone name a finding in science that did NOT
  follow this method?

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• Scientific Method -
• Methodologies do all share these features
• Natural phenomena only
• Utilizes logic
• All claims can generate testable predictions
• Based on observable evidence (though not
  necessarily observable phenomena)
• Findings can be repeated
• No such thing as final proof, the explanation
  that best fits the current evidence is accepted
  for the time being

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How Scientists Work

• A generalized method we will use
• State the Problem/Ask a Question
• Form a Hypothesis Make a Prediction
• Test Prediction with a Controlled Experiment
• Record and Analyze Data or Results
• Draw a Conclusion Based on Analysis
• (Evaluate whether the hypothesis was supported by
  seeing if the prediction turned out to be
  accurate)
• Publish and Repeat Investigations

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Ask a Question

• Scientists form questions when they observe
  nature through their senses (sight, hearing,
  touch, smell)
• Examples
• Some peaches are juicy and sweet. Others are
  spongy with very little flavor.
• What makes some peaches juicier than others?
• My neighbor has thick, green grass. Mine is brown
  in spots and is thin.
• What does grass need to be healthy?

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Ask a Question Practice

• Form scientific questions about the pictures
  below.

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Writing Hypotheses Predictions

• Hypothesis a proposed explanation for a set of
  observations or possible answer to a question
• Must be testable, or its not scientific
• Write the hypothesis as a clear statement, do not
  say I think that .
• Prediction a statement of what you expect to
  observe if the hypothesis is accurate
• A description of specific data you will obtain.
• Its how you know if the hypothesis is right
• ATTENTION - It is okay for your pre-lab
  hypothesis and prediction to be wrong! Never
  change your hypothesis after an experiment to
  make it fit!

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Hypothesis Prediction Practice

• Write a possible hypothesis and prediction
  foreach of the following observations.
• The plants in Mr. Smiths living room are large,
  healthy and green but the plants in Mr. Smiths
  dining room are small and yellowish in color.
• All of the fish in the classroom fish tank are
  healthy except for the algae eaters that keep
  dying.
• There are only a few un-popped kernels in the
  popcorn that has been stored in the kitchen but a
  lot of kernels left in the popcorn that has been
  stored in the basement.

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Testing the Hypothesis Designing Controlled
Experiments

• Whenever possible, an experiment should be
  designed to have only ONE variable that is
  changed at a time. (AKA Controlled Experiment)
• Control or Controlled Variable/s the variable/s
  that you are NOT testing, so they are purposely
  kept the same at all times
• Independent (Manipulated) Variable the ONE
  variable that is deliberately changed to see what
  happens
• Dependent (Responding) Variable the variable
  that is thought to be affected by the independent
  variable
• Experimental Group the adjusted or special
  group in which the independent variable is
  tweaked
• Control Group the normal group used as a
  standard for comparison for the experimental group

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Controlled Experiment Practice

• Hypothesis Tomato plants given fertilizer will
  produce more tomatoes than plants that are not
  fertilized.
• Plant A Plant B
• Both plants are given the same soil, amount of
  water and sun, temperature, pot size, and growth
  time.
• Plant B is fertilized once a week.
• What are the controlled variables, the
  manipulated variable, and the responding
  variable?
• Which is the control and the experimental group?

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Why change only one variable?
Plant B 7 hours of sunlight per day l L of water
every 2 days gallon sized pot 35º C for 9
weeks fertilized once a week
Plant A 5 hours of sunlight per day l L of water
every 4 days quart sized pot 30º C for 6 weeks no
fertilization
Cant tell!
Why did plant B grow more tomatoes? By only
changing one variable, the experimenter can
conclude that changes in the responding variable
are due only to changes in the one manipulated
variable.
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Experimental Design Practice

• Describe why the experiment below is poorly
  designed. Write a prediction for the hypothesis
  and then re-design the experiment to make it
  better. Identify all variables and groups.
• Hypothesis Bacteria exposed to antibiotics will
  be killed.

Plate A Stored on counter (22º C) Given
penicillin Stored in light Not given nutrients
Plate B Stored in incubator (35º C) Given
ampicillin Stored in dark Given nutrients
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Recording and Analyzing Data and Results

• Data - observations and measurements that are
  made in an experiment
• All experimental data must include units. (9 cm,
  20 sec, 98º C, etc.)
• Data is often represented using tables and graphs
  which must be thoroughly labeled.
• Two major types of measurements/observations
• Quantitative data that can be measured in
  numbers. (Ex. number of objects, dimensions,
  duration, mass, etc.)
• Qualitative data that is based on non-numerical
  descriptions. (Ex. color, health, etc.)

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Proper Tables and Graphs
Lets list what this table does correctly! This
list the list of what YOUR tables must do!
Effect of Temperature on Seed Germination
Storage Location Temperature Storage Location Temperature Storage Location Temperature
Inside Room Temp Inside Freezing Temp Outside Winter Temp
Percent of germinated seeds 0 80 85
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Representing Data in Graphs
Effect of Temperature on Seed Germination





100 80 60 40 20 0
Percent of Germinated Seeds ()
- Inside Room
- Inside Freezing
- Outside Winter
Storage Location Temperature
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Choosing Bar vs Line Graphs

• Bar graph Used when there is at least one
  qualitative variable
• Line graph Used for when both variable are
  quantitative
• Manipulated/independent variable always placed on
  X-axis
• Responding/dependent variable on Y-axis

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Graph Examples
Town of Students
Canton 9
Stoughton 2
Norwood 1
Westwood 4
Dedham 3
Milton 2
Randolph 1
Sharon 1
Hyde Park 1

• Number of students per town what kind of graph,
  bar or line? Which data goes on which axis?

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Graph Examples
Height (cm) of Students
150 2
151 2
152 3
153 6
154 5
155 3
156 1
157 1

• Number of students at different heights what
  kind of graph, bar or line? Which data goes on
  which axis?

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Bar or Line Graph?

• Number of American Thrushes living in each of
  five forests
• 100 students choices for their favorite lunch
• Comparing the number of chromosomes to the number
  of genes
• The number of mates attracted by red vs yellow vs
  blue-beaked parrots
• The growth of a seedling (days old vs height)

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Representing Data Practice

• Using the data below, redo the data table and
  graph to improve them.
• Results Frogs given caffeine jumped 27cm and
  frogs not given caffeine jumped 20 cm.

Frog not given caffeine Frog given caffeine
Distance of jump 20 27
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Drawing Conclusions

• Conclusion a final summation of experimental
  results
• A conclusions main purpose is to evaluate your
  initial ideas (hypothesis prediction) using
  your data
• Sometimes a hypothesis must be rejected, leading
  to a new experiment or even a new hypothesis.

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Draw Conclusions ExampleBased on the previous
frog experiment.

• This investigation aimed to determine whether
  caffeine affects the distances frogs jump. Based
  upon the fact that caffeine is a stimulant,
  highly caffeinated frogs were predicted to jump
  further. The results supported this, showing
  that frogs given caffeine jumped an average of
  7cm farther than frogs that were not given
  caffeine. All other variables having been
  controlled, it can be safely concluded that
  caffeine increases jump distance in frogs.

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Draw Conclusions Practice

• Examine the hypothesis and experimental results
  below, and write an appropriate conclusion.
• Hypothesis Carrots require high nitrogen levels
  for best growth.
• Results Carrots that were not given nitrogen
  grew to an average of 6 inches. Carrots given low
  levels of nitrogen grew to an average of 10
  inches. Carrots given high levels of nitrogen
  grew to an average of 4 inches.

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Making Observations vs. Making Inferences
Why is this an important distinction in science?

• Observation Statement of information gathered
  from one of the five senses.
• Inference - Logical interpretation based on prior
  knowledge and experience
• Example
• You offer me a chocolate cookie. I say no thank
  you.
• OBSERVATION I did not eat the cookie
• INFERENCE I am on a diet, I do not like
  chocolate, I am not hungry, I am allergic to
  cookies

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Communicate Results

• Scientists always report their results through
  journals and scientific papers.
• This allows others to skeptically evaluate their
  results, repeat their investigation, integrate
  their findings into other studies, and can lead
  to further questions and investigations.

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Scientific Language

• The scientific process has a language of its own.
• Sometimes, this language diverges from colloquial
  English.
• Science words can be different from English
  words even when they look exactly the same.
• For example, the words for different kinds of
  scientific outcomes and models

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Scientific Language

• Fact (Colloquial English) ?
• Fact (Scientific) An observation that has been
  made repeatedly.
• Example Two negative poles move away from each
  other.

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Scientific Language

• Law (Colloquial English) ?
• Law (Scientific) A description of patterns in a
  relationship between quantities.
• Example p q 1, (p q)2 (Hardy-Weinbergs
  Law)

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Scientific Language

• Theory (Colloquial English) ?
• Theory (Scientific) A powerful explanation of
  related natural phenomena.
• Example Matter is made up of atoms, properties
  of matter come from atomic behavior (Atomic
  theory)