Chapter 1 Themes in the Study of Life. What is Biology?
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Transcript of Chapter 1 Themes in the Study of Life. What is Biology?
Chapter 1Themes in the Study of Life
What is Biology?
What is Biology?◦Scientific study of Life◦Filled with QUESTIONS
Good Questions Questions that can be investigated
What is Life?
What is Life?
7 Properties of Life
What is Life?
7 Properties of Life◦Order◦Evolutionary adaptation◦Responding to the environment◦Growth and development◦Reproduction◦Energy processing◦Regulation
What are the Major Themes of Biology
Major Themes of Biology◦New properties emerge at each level in the
biological hierarchy◦Organisms interact with their environments,
exchanging matter and energy◦Structure and function are correlated at all
levels of biological organization◦Cells are an organism’s basic units of
structure and functions◦The continuity of life is based on heritable
information in the form of DNA◦Feedback mechanisms regulate biological
systems
Evolution“Nothing makes sense except in the light of evolution”
- Who Said This?
Evolution“Nothing makes sense except in the light of evolution”
Dobzhansky
Evolution“Nothing makes sense except in the light of evolution”
Dobzhansky
Core Theme◦Evolution accounts for the unity and
diversity of life◦Its importance will demonstrate a large
role in this course Can always refer to Section 1.2 throughout
the semester
How do scientists pose and answer questions about the natural world?
How is Biology examined?
How is Biology examined?
Reductionist approach Holistic approach Systems biology
How is Biology examined?
Reductionist approach
How is Biology examined?
Reductionist approach Reduce complex systems to simple components
How is Biology examined?
Reductionist approach Reduce complex systems to simple components
Holistic approach
How is Biology examined?
Reductionist approach Reduce complex systems to simple components
Holistic approach Larger-scale, with the objective of understanding how the emergent properties work together
How is Biology examined?
Reductionist approach Reduce complex systems to simple components
Holistic approach Larger-scale, with the objective of understanding how the emergent properties work together
Systems biology
How is Biology examined?
Reductionist approach Reduce complex systems to simple components
Holistic approach Larger-scale, with the objective of understanding how the emergent properties work together
Systems biology Goal is to construct models for the behavior of a whole systems
What is inquiry?
What is inquiry? Inquiry is the search for information and
explanation that often focuses on specific questions
Scientists use two main forms of scientific inquiry
Discovery ScienceHypothesis-Based Science
Scientists use two main forms of scientific inquiry
Discovery Science
Scientists use two main forms of scientific inquiry
Discovery Science Describing nature More qualitative in nature Can have quantitative aspects Describes natural processes Uses observation to gather information
(directly or indirectly) with tools Recorded observations are called data
Scientists use two main forms of scientific inquiry
Hypothesis-Based Science
Scientists use two main forms of scientific inquiry
Hypothesis-Based Science Describing nature More qualitative in nature Can have quantitative aspects Describes natural processes Uses observation to gather information
(directly or indirectly) with tools Recorded observations are called data
What is a hypothesis?
What is a hypothesis?Tentative answer to a well-
framed question◦Explanation on trial
Educated Guess that is based on experience and the data available from Observation
What makes a Good Hypothesis?
What makes a Good Hypothesis?TestableFalsifiableCannot be PROVENGains credibility by surviving attempts to falsify it
What makes a Good Hypothesis?Testable
What makes a Good Hypothesis?Testable A way to check the validity
What makes a Good Hypothesis?Testable A way to check the validity
Falsifiable
What makes a Good Hypothesis?Testable A way to check the validity
Falsifiable There must be some observation or experiment that could reveal if such an idea is NOT true
Generally, scientists frame two or more alternative hypotheses and design experiments to falsify
What makes a Good Hypothesis?Testable A way to check the validity
Falsifiable There must be some observation or experiment that could reveal if such an idea is NOT true
Generally, scientists frame two or more alternative hypotheses and design experiments to falsify
Cannot be PROVEN
What makes a Good Hypothesis?Testable A way to check the validity
Falsifiable There must be some observation or experiment that could reveal if such an idea is NOT true
Generally, scientists frame two or more alternative hypotheses and design experiments to falsify
Cannot be PROVEN Testing supports a hypothesis not by Proving it, but instead by not eliminating it through the falsification
It’s impossible to test ALL alternative hypothesis
What makes a Good Hypothesis?Testable A way to check the validity
Falsifiable There must be some observation or experiment that could reveal if such an idea is NOT true
Generally, scientists frame two or more alternative hypotheses and design experiments to falsify
Cannot be PROVEN Testing supports a hypothesis not by Proving it, but instead by not eliminating it through the falsification
It’s impossible to test ALL alternative hypothesis
Gains credibility by surviving attempts to falsify it
What are the Types of Data?
Types of DataQualitativeQuantitative
Types of DataQualitative
Types of DataQualitative
Recorded descriptions rather than numerical General observations Colors
Types of DataQualitative
Recorded descriptions rather than numerical General observations Colors
Quantitative
Types of DataQualitative
Recorded descriptions rather than numerical General observations Colors
Quantitative Recorded measurements Numerical in nature
What are theTypes of Reasoning
Types of Reasoning
Inductive ReasoningDeductive Reasoning
Types of Reasoning
Inductive Reasoning
Types of ReasoningInductive Reasoning
From induction Derive generalizations from a large number of
specific observations Ex:
If every organisms that you have studied is made of cells, then it would be acceptable to induce that all organisms are made of cells.
Types of Reasoning
Inductive Reasoning From induction Derive generalizations from a large number of
specific observations Ex:
If every organisms that you have studied is made of cells, then it would be acceptable to induce that all organisms are made of cells.
Deductive Reasoning
Types of Reasoning
Inductive Reasoning From induction Derive generalizations from a large number of specific
observations Ex:
If every organisms that you have studied is made of cells, then it would be acceptable to induce that all organisms are made of cells.
Deductive Reasoning Logic flows from general to specific Usually take the form of prediction of experimental or
observational results Ex:
If all organisms are made of cells, and humans are organisms, then humans are composed of cells
Scientific Method◦Ask a Question◦Do Background Research◦Construct a Hypothesis◦Test Your Hypothesis by Doing an
Experiment◦Analyze Your Data and Draw a
Conclusion◦Communicate Your Results
What is Experimental Design?
INTEGRATING EXPERIMENTAL DESIGN INTO
SCIENCE
Experimental Design: The ProcessPaper airplane - everybody builds
oneObserve the plane’s flight
◦Ready, set, hold it …◦How do we determine which is best?
5 minutes to modify, make one change
Write your hypothesis on your plane
Leading QuestionsHow did you act on your plane?What did you purposefully
change about your plane?How did you determine your
plane’s response?What remained the same
about about your plane?
Action PurposefulChange
ResponseTo Change
RemainedThe Same
Experimental Design DiagramTitle: The effect of ...IV... on ...DV...
Hypothesis: If the ...IV... is modified in this way,then this will happen to the ...DV...
Independent variable:
these boxesshow how theIV is modified
_____trials _____trials _____trials _____trials _____trials
Dependent Variable:
Constants:
Control:
Experimental Design Problems Compost & Bean Plants
After studying about recycling, members of John's biology class investigated the effect of various recycled products on plant growth. John's lab group compared the effect of different aged grass compost on bean plants. Because decomposition is necessary for release of nutrients, the group hypothesized that older grass compost would produce taller bean plants Three flats of bean plants (25 plantslflat) were grown for 5 days. The plants were then fertilized as follows: (a) Flat A: 450 g of three-month-old compost, (b) Flat B: 450 g of six-month-old compost, and (c) Flat C: 0 g compost. The plants received the same amount of sunlight and water each day At the end of 30 days the group recorded the height of the plants (cm).
Experimental Design Diagram
Title: The effect of different aged compost on beanplant growth.
Hypothesis: If older compost is applied, then plantgrowth will be increased.
Independent variable: Age of Compost
these boxesshow how theIV is modified
3 month oldcompost
6 month oldcompost No compost
# trials 25 trials 25 trials 25 trials
Dependent Variable: Height of plants (cm)
Constants: amount of light, water, compost
Control: no compost
Scenario 2 Metals & Rusting Iron
In chemistry class, Allen determined the effectiveness of various metals in releasing hydrogen gas from hydrochloric acid. Several weeks later, Allen read that a utilities company was burying lead next to iron pipes to prevent rusting Allen hypothesized that less rusting would occur with the more active metals. He placed the following into separate beakers of water: (a) 1 iron nail, (b) 1 iron nail wrapped with an aluminum strip, (c) 1 iron nail wrapped with a magnesium strip, (d) 1 iron nail wrapped with a lead strip. He used the same amount of water, equal amounts (mass) of the metals and the same type of iron nails. At the end of 5 days, he rated the amount of rusting as small, moderate, or large. He also recorded the color of the water.
Experimental Design Diagram
Title: The effectiveness of various metals in preventing the rusting of iron.
Hypothesis: I f the chemical activity of the metallic wrapper is increased, then less rusting of iron will occur.
Independent variable: Type of metal wrapping strip these boxes show how the IV is modified
Iron nail with no metal
Iron nail with magnesium
Iron nail with aluminum
Iron nail with lead
# trials 1 trial 1 trial 1 trial 1 trial
Dependent Variable: amount of rusting , color of water
Constants: amount of water, mass of metal, type of nail
Control: nail with no metal
Perfumes & Bee's Behavior JoAnna read that certain perfume esters would agitate bees.
Because perfume formulas are secret, she decided to determine if the unknown Ester X was present in four different perfumes by observing the bees' behavior. She placed a saucer containing 10 ml of the first perfume 3 m from the hive. She recorded the time required for the bees to emerge and made observations on their behavior. After a 30-minute recovery period, she tested the second, third, and fourth perfumes. All experiments were conducted on the same day when the weather conditions were similar, e.g., air, temperature and wind.
Experimental Design DiagramTitle: The effect of various perfumes on the behavior of bees.
Hypothesis: I f the perfume contains Ester X, then the bees will display agitated behavior.
Independent variable: Type of perfume these boxes show how the IV is modified
Perfume 1 Perfume 2 Perfume 3 Perfume 4
# trials 1 trial 1 trial 1 trial 1 trial
Dependent Variable: time to emerge , behavior of bees
Constants: amount of perfume, weather, distance from hive
Control:
Fossils and Cliff DepthSusan observed that different kinds and
amounts of fossils were preset in a cliff behind her house. She wondered why changes in fossils content occurred from the top to the bank. She marked the bank at five positions: 5,10,15, 20, and 25m from the surface. She removed 1 bucket of soil from each of the positions and determined the kind and number of fossils in each sample.
Experimental Design DiagramTitle: The effect of depth on the different
types and amounts of fossils.Hypothesis: If depth increases in a fossil bank,
then different fossils will occur.Independent Variable: Depth of soil
Modifications 5 10 15 20 25
# of Trials 1 1 1 1 1
Dependent Variable: Amount and type of fossils.
Constant: 1 bucketControl ?
Aloe vera and Planaria Jackie read that Aloe vera promoted healing of burned
tissue. She decided to investigate the effect of varying amounts of aloe vera and regeneration of planaria. She bisected the planaria to obtain 10 parts (5 heads and 5 tails) for each experimental group. She applied concentrations of 0%, 10%, 20%, and 30% Aloe vera to the groups. Fifteen ml of Aloe vera solutions were applied. All planaria were maintained in a growth chamber with identical food, temperature, and humidity. On day 15, Jackie observed the regeneration of the planaria parts and categorized deeloped as full, partial, or none.
Experimental Design Diagram
Title: The effect of aloe vera on regeneration of planaria.
Hypothesis: If more aloe vera is used then there will be an increased amount of aloe vera.
Independent Variable: Percentage of Aloe VeraModifications 10% 20% 30%
# of Trials 10 10 10
Dependent Variable: amount of regeneration
Constant: food, temperature, humidity
Control : 0% aloe vera