Good Stuff Happens in 1:1 Meetings: Why you need them and how to do them well
Ap bio lecture ch1 a view of life
1. A View of Life
WarmUp Questions
3.What are the eleven levels of biological organization in order from largest to
smallest?
5.Name 4 characteristics of life.
7.Can you differentiate between inductive and deductive reasoning?
4. A View of Life
Biologists use various forms of inquiry to
explore life
At the heart of science is inquiry
◦ A search for information and explanation, often
focusing on specific questions
Biology blends two main processes of scientific
inquiry
◦ Discovery science
◦ Hypothesis-based science
5. A View of Life
◦ Describes natural structures and processes as
accurately as possible through careful observation
and analysis of data
6. A View of Life
Data
◦ Are recorded observations
◦ Can be quantitative or qualitative
Figure 1.24
7. A View of Life
In inductive reasoning
◦ Scientists derive generalizations based on a large
number of specific observations
8. A View of Life
In science, inquiry that asks specific questions
◦ Usually involves the proposing and testing of
hypothetical explanations, or hypotheses
9. A View of Life
In science, a hypothesis
◦ Is a tentative answer to a well-framed question, an
explanation on trial
◦ Makes predictions that can be tested
10. A View of Life
We use simple hypotheses ALL THE TIME
Observations
Questions
Hypothesis # 1: Hypothesis # 2:
Dead batteries Burnt-out bulb
Prediction: Prediction:
Replacing batteries Replacing bulb
will fix problem will fix problem
Test prediction Test prediction
Figure 1.25 Test falsifies hypothesis Test does not falsify hypothesis
11. A View of Life
In deductive reasoning
◦ The logic flows from the general to the specific
If a hypothesis is correct
◦ Then we can expect a particular outcome
12. A View of Life
A scientific hypothesis must have two
important qualities
◦ It must be testable
◦ It must be falsifiable
13. A View of Life
The scientific method
◦ Is an idealized process of inquiry
Very few scientific inquiries
◦ Adhere to the “textbook” scientific method
14. A View of Life
In mimicry
◦ A harmless species resembles a harmful species
Flower fly
(non-stinging)
Honeybee (stinging)
Figure 1.26
15. A View of Life
In this case study
◦ Mimicry in king snakes is examined
◦ The hypothesis predicts that predators in non–coral
snake areas will attack king snakes more frequently
than will predators that live where coral snakes are
present Scarlet king snake
Key
Range of scarlet king snake
Range of eastern color snake
North
Carolina
South
Carolina
Eastern coral snake
Figure 1.27 Scarlet king snake
16. A View of Life
To test this mimicry
hypothesis
◦ Researchers made hundreds
of artificial snakes, an
experimental group
resembling king snakes and
a control group of plain
(a) Artificial king snake
brown snakes
Figure 1.28 (b) Brown artificial snake that has been attacked
17. A View of Life
After a given period
of time Key
Key
% of attacks on artificial king snakes
◦ The researchers % of attacks on brown artificial snakes
collected data that fit a Field site with artificial snakes
key prediction In areas where coral snakes
17%
were absent, most attacks 83%
were on artificial king snakes
X
North XX X
XX
Carolina X
South XX
Carolina X
X X
XX 16%
84%
In areas where coral
snakes were present,
most attacks were on brown
Figure 1.29 artificial snakes
18. A View of Life
Experiments must be designed to test
◦ The effect of one variable by testing control groups
and experimental groups in a way that cancels the
effects of unwanted variables
19. A View of Life
Science cannot address supernatural
phenomena
◦ Because hypotheses must be testable and falsifiable
and experimental results must be repeatable
20. A View of Life
A scientific theory
◦ Is broad in scope
◦ Generates new hypotheses
◦ Is supported by a large body of evidence
21. A View of Life
Defining Life
◦ Emergent Properties
◦ Organized
◦ Materials and Energy
◦ Response
◦ Reproduce and Develop
◦ Adaptations and Natural Selection
Biosphere Organization
◦ Human Population
◦ Biodiversity
Classification
The Scientific Method
21
22. A View of Life
Living things vs. nonliving objects:
◦ Comprised of the same chemical elements
◦ Obey the same physical and chemical laws
The cell is the smallest, most basic unit of all
life
◦ Familiar organisms are multicellular
◦ Some cells independent – single-celled organisms
22
24. A View of Life
Emergent Properties – Biological organization
◦ Levels range from extreme micro to global
◦ Each level up:
More complex than the preceding level
Properties:
A superset of preceding level’s properties emerge from
interactions between components
24
27. A View of Life
Energy - the capacity to do work
◦ The sun:
Ultimate source of energy for nearly all life on Earth
Drives photosynthesis
◦ Metabolism - all the chemical reactions in a cell
Homeostasis - Maintenance of internal conditions
within certain boundaries
27
29. A View of Life
Living things detect changes in environment
Response often involves movement
◦ Vulture can detect and find carrion a mile away
◦ Monarch butterfly senses fall and migrates south
◦ Microroganisms follow light or chemicals
◦ Even leaves of plants follow sun
Responses collectively constitute behavior
29
30. A View of Life
Organisms live and die
Must reproduce to maintain population
Multicellular organisms:
◦ Begins with union of sperm and egg
◦ Developmental instructions encoded in genes
Composed of DNA
Long spiral molecule in chromosomes
30
32. A View of Life
Adaptation
◦ Any modification that makes an organism more
suited to its way of life
◦ Organisms, become modified over time
◦ However, organisms very similar at basic level
Suggests living things descended from same ancestor
Descent with modification - Evolution
Caused by natural selection
32
33. A View of Life
Population - Members of a species within an
area
Community - A local collection of interacting
populations
Ecosystem - The communities in an area
considered with their physical environment
How chemicals are cycled and re-used by organisms
How energy flows, from photosynthetic plants to top
predators
33
36. A View of Life
Ecosystems negatively impacted by human
populations
◦ Destroyed for agriculture, housing, industry, etc.
◦ Degraded and destabilized by pollution
However, humans depend upon healthy ecosystems
for
◦ Food
◦ Medicines
◦ Raw materials
◦ Other ecosystem processes
36
37. A View of Life
Biodiversity:
◦ The total number of species (est. 15 million)
◦ The variability of their genes
◦ The ecosystems in which they live
Extinction:
◦ The death of the last member of a species
◦ Estimates of 400 species/day lost worldwide
37
38. A View of Life
Taxonomy:
◦ The rules for identifying and classifying organisms
◦ Hierarchical levels (taxa) based on hypothesized
evolutionary relationships
◦ Levels are, from least inclusive to most inclusive:
Species, genus, family, order, class, phylum, kingdom,
and domain
A level usually includes more species than the level
below it, and fewer species than the one above it
38
39. A View of Life 39
Taxon Human Corn
Domain Eukarya Eukarya
Kingdom Animalia Plantae
Phylum Chordata Anthophyta
Class Mammalia Liliopsida
Order Primates Commelinales
Family Hominidae Poacae
Genus Homo Zea
Species H. sapiens Z. mays
40. A View of Life
Bacteria
◦ Microscopic unicellular prokaryotes
Archaea
◦ Bacteria-like unicellular prokaryotes
◦ Extreme aquatic environments
Eukarya
◦ Eukaryotes – Familiar organisms
40
43. A View of Life
Archaea – Kingdoms still being worked out
Bacteria - Kingdoms still being worked out
Eukarya
◦ Kingdom Protista
◦ Kingdom Fungi
◦ Kingdom Plantae
◦ Kingdom Animalia
43
45. A View of Life
Binomial nomenclature (two-word namess)
Universal
Latin-based
◦ First word represents genus of organism
◦ Second word is specific epithet of a species within
the genus
◦ Always Italicized asa Genus species (Homo sapiens)
◦ Genus may occur alone (Homo), but not specific
epithet
45
46. A View of Life
Begins with observation
◦ Scientists use their five senses
◦ Instruments can extend the range of senses
Hypothesis
◦ A tentative explanation for what was observed
◦ Developed through inductively reasoning from
specific to general
46
48. A View of Life
Experimentation
◦ Purpose is to challenge the hypothesis
◦ Designed through deductively reasoning from
general to specific
◦ Often divides subjects into a control group and an
experimental group
◦ Predicts how groups should differ if hypothesis is
valid
If prediction happens, hypothesis is unchallenged
If not, hypothesis is unsupportable
48
49. A View of Life
Results
◦ Observable, objective results from an experiment
◦ Strength of the data expressed in probabilities
◦ The probability that random variation could have
caused the results
Low probability (less than 5%) is good
Higher probabilities make it difficult to dismiss
random chance as the sole cause of the results
49
50. A View of Life
The results are analyzed and interpreted
Conclusions are what the scientist thinks
caused the results
Findings must be reported in scientific
journals
Peers review the findings and the conclusions
Other scientists then attempt to duplicate or
dismiss the published findings
50
51. A View of Life
Scientific Theory:
◦ Joins together two or more related hypotheses
◦ Supported by broad range of observations,
experiments, and data
Scientific Principle / Law:
◦ Widely accepted set of theories
◦ No serious challenges to validity
51
52. A View of Life
Experimental (Independent) variable
◦ Applied one way to experimental group
◦ Applied a different way to control group
Response (dependent) variable
◦ Variable that is measured to generate data
◦ Expected to yield different results in control versus
experimental groups
52
53. A View of Life
Observations:
◦ Nitrate fertilizers boost grain crops, but may
damage soils
◦ When grain crops are rotated with pigeon pea it
adds natural nitrogen
Hypothesis:
◦ Pigeon pea rotation will boost crop production as
much as nitrates
◦ Pigeon pea rotation will NOT damage soils
53
55. A View of Life
Experimental Design
◦ Control Group
Winter wheat planted in pots without fertilizer
◦ Experimental Groups
1-Winter wheat planted in pots with 45 kg/ha nitrate
2-Winter wheat planted in pots with 90 kg/ha nitrate
3-Winter wheat planted in pots that had grown a crop
of pigeon peas
◦ All groups treated identically except for above
55
57. A View of Life
Experimental Prediction:
◦ Wheat production following pigeon pea rotation will
be equal or better than following nitrate fertilizer
Results
◦ 45 kg/ha produced slightly better than controls
◦ 90 kg/ha produced nearly twice as much as
controls
◦ Pigeon pea rotation did not produce as much as the
controls
57
58. A View of Life
Conclusion
◦ Research hypothesis was not supported by results
◦ However, research hypothesis was not proven false
by negative results
Revised experiment
◦ Grow wheat in same pots for several generations
◦ Look for soil damage in nitrate pots and improved
production in pigeon pea pots
58
59. A View of Life
Results
◦ After second year:
Production following nitrates declined
Production following pigeon pea rotation was greatest
of all
◦ After third year
Pigeon pea rotation produced 4X as much as controls
Revised conclusions
◦ Research hypothesis supported
◦ Pigeon pea rotation should be recommended over
nitrates
59
61. A View of Life
Defining Life - Emergent Properties
◦ Materials and Energy
◦ Reproduction and Development
◦ Adaptations and Natural Selection
Biosphere Organization
◦ Human Population
◦ Biodiversity
Classification
The Scientific Method
61