Transcript Biology
Welcome to General
Cell Biology
Study Habits
• Find out what works best for YOU
• Try different methods
– Combine methods
• Use shorthand
• Read the chapter BEFORE lecture and be
prepared with any questions
• Study EVERY day
What is science?
To Know
• The Goal of Science
1) deals only with the natural world
2) to collect and organize information
3) propose explanations that can be tested
• Seeks natural causes to phenomenon
– Therefore limited to things that we can OBSERVE
and MEASURE
What is science?
To Know
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Explanatory
Testable
Reproducible
Predictive
Tentative
What is Biology
• Study of life
– Encompasses
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Ethology
Evolutionary Biology
Physiology
Genetics
Molecular Biology
Morphology
Systematics
Ecology
And more…..
Approaches
• Discovery- observational
– Uses inductive reasoning
• Hypothesis-basedexperimental
– Uses deductive reasoning
Hypothesis based science
Hypothesis- a tentative statement that
proposes a possible explanation to some
phenomenon or event
– Testable
– Tentative relationship is stated
– Simple and concise
– Falsifiable
• Accept or reject
Inferences, Predictions &
Hypotheses
• Inferences are a logical interpretation
based on prior knowledge or experience
• Predictions “guess” what will happen
• Hypothesis presents a relationship, which
attempts to explains what will happen
– Specific, testable prediction about what will
happen
Language of a hypothesis
• Contain the dependent and independent
variables
– If leaf color change is affected by (related to)
temperature , then exposing plants to low
temperatures will result in changes in leaf
color.
Language of a hypothesis
Most commonly, hypotheses take three formats:
• a question, "Does temperature affect
fermentation?"
• a conditional statement, "Temperature may
affect fermentation."
• an If, then statement, "If fermentation rate is
related to temperature, then increasing the
temperature will increase gas production.
Examples
• If the diffusion rate (dependent variable) through
a membrane is related to molecular size,
(independent variable)
then the smaller the molecule the faster it will
pass through a membrane.
• If the rate of photosynthesisis related to wave
lengths of light, then exposing a plant to different
colors of light will produce different amounts of
oxygen.
Scientific method
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Observation
Question
Hypothesis
Experimentation
– Controlled
– Replication
• Analysis of results
• Evaluate hypothesis
Why do I care about Hypothesis
testing and scientific method?
• Used in every day life and decision making
– Ex: Medical- use scientific method to
determine cause of patients ailment
• Understand the world around us
Scientific Theory
Explanation of something that has
been substantiated by a large amount
of data collected over multiple
experiments
Best possible explanation at the time
based on experiments and available
data
Can be altered, revised, adapted or
simply abandoned as new data
becomes available
Reasoning
• Inductive- Extrapolate general principles
from specific examples
– A conclusion is arrived at based on a set of
observations
• Deductive- Extrapolate specific
conclusions from general principles
– If A then B
Reasoning
Inductive
All observed crows are black.
Therefore:
All crows are black.
Deductive
All men are mortal
Socrates is a man
Therefore, Socrates is mortal
Experiments & Theories
• Experiments & hypotheses only test
NEVER prove theories
– The very next experiment may falsify theory
– Always falsify a hypothesis, not prove it
Controls & Variables
• Independent- single manipulated variable
• Dependent- thing that is measured,
counted or observed. Changes in
response to independent
• Controlled variables- things that are kept
constant
Groups
• Experimental- group that is exposed to the
independent variable
• Control group- group that is exposed to
everything BUT the independent variable
Spontaneous Generation
Redi’s blowfly experiment
• Living things arrive from lifeless matter
– Air had a “life force”
• Rotting meat, when left, produced flies
– Therefore, flies come from rotten meat
Spontaneous Generation
• Observation- Flies spontaneously appear on rotting
meat
• Question- Does rotting meat produce flies?
• Hypothesis- If rotting meat is related to the creation of
flies then any flask with rotten meat will produce flies
• Prediction- A flask of rotting meat will produce flies in
21 days
• Experimentation- 3 jars of meat were subjected to
being open, semi-sealed with parchment paper or sealed
while other variables remained identical
• Analysis of results- No flies were present in closed
jars, semi-closed jars had fly eggs on the parchment,
open jars contained flies
• Evaluate hypothesis against results- Reject
hypothesis as sealed jars did not produce flies and semisealed jars had fly eggs on the parchment paper
©Barrons 2009
• What would happen if no control group
was included?
In-class Exercise
• Get into groups
• Each group identify a scientific question,
hypothesis and experimental outcome for each
scenario
– Don’t worry about figuring out an experiment, just
make up the results of one
• Decide if your outcome supports or refutes your
hypothesis
• Scenario 1-While hiking in the forest one day, you
notice that while on the left side of the trail, the frogs
are bright green, but on the right, they are a mottled
green-brown color.
• Scenario 2- As a nurse, one of your patients
presents with an unusually low temperature, but no
other symptoms
• Scenario 3-You are fishing out in Puget Sound and
find that all the other fishermen are pulling up
salmon, but you are catching flounder.
Data Interpretation
• Data analysis is a body of methods that
help to describe facts, detect patterns,
develop explanations, and test
hypotheses.
Data Interpretation
• Look At the Data / Think About the Data /
Think About the Problem / Ask what it is
you Want to Know
• Estimate the Central Tendency of the Data
• Look at the Exceptions to the Central
Tendency (variation)
Data Interpretation
• Average
– Sum of numbers / number of numbers
• Standard Deviation- measure of how
variable the data is
• Sampling error- difference between results
from subset of data and the whole
• Statistically Significant- unlikely to occur
by chance
Data Interpretation
Standing HR
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Organization of Life
Life’s levels of
organization
define the
scope of
biology
Hierarchical organization
• Organized according to complexity
• Emergent properties
– Properties that were not present at the
previous lower level and result from the
specific arrangement and interactions between
components
• “The whole is greater than the sum of its parts”
Environmental interactions
Living organisms
and their
environments form
interconnecting
webs
Environmental Interactions
• Autotrophs
– Organisms that produce organic compounds from
inorganic compounds
• “Producers”
• Heterotrophs
– Organisms that obtain nutrients from other organisms
• “Consumers”
• Decomposers
– Decay organic matter, releasing energy back into the
ecosystem
• Saprobes
Common features of all living
forms
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Order/organization
Regulation
Growth & Development
Energy utilization/processing
Response to the environment
Reproduction
Evolution