ohhs ap bio chapter 1 (class presentation)
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Chapter 1Introduction: Themes in the Study of Life
Big Picture
•Evolution: the process of change that has transformed life on Earth.•Biology: the scientific study of life.• It is about asking questions:•HOW?•WHY?
Themes in Biology
Order
Evolutionary adaptation
Responseto theenvironment
Reproduction
Growth anddevelopment
Energyprocessing
Regulation
8 Themes of AP Biology
1. Science as a Process2. Evolution3. Energy Transfer4. Continuity and Change5. Relationship of Structure to Function6. Regulation7. Interdependence in Nature8. Science, Technology, and Society
Concept 1.1Themes connect the concepts of biology.
Evolution
•Overarching theme of biology.•Makes sense of everything we know about living organisms.•All organisms living on Earth are modified descendants of common ancestors.
Biological Hierarchy•Life at different levels.
The biosphere
Communities
Populations
Organisms
Ecosystems
Organs and organ systems
Cells
Cell
Organelles
Atoms
MoleculesTissues
10 µm
1 µm
50 µm
Emergent Properties:• Result from the arrangement and interactions of
parts within a system.
Reductionism:• The reduction of complex systems to simpler
components that are more manageable to study.
Systems Biology:• Constructs models for the dynamic behavior of
the whole biological system – function together.
Organisms Interact with their Environments•Every organism interacts with its environment, including nonliving factors and other organisms.
Ecos
yste
m D
ynam
ics
Sunlight
Ecosystem
Heat
Heat
Cyclingof
chemicalnutrients
Producers(plants and other
photosyntheticorganisms)
Chemical energy
Consumers(such as animals)
Ener
gy C
onve
rsio
n
Structure and Function
(a) Wings
(c) Neurons
(b) Bones
Infoldings ofmembrane
Mitochondrion
(d) Mitochondria0.5 µm100 µm
Cells are the basic unit of structure and function.
•Lowest level of organization that can perform all activities required for life.
1 µmOrganelles
Nucleus (contains DNA)
Cytoplasm
Membrane
DNA(no nucleus)
Membrane
Eukaryotic cellProkaryotic cell
Continuity of life is based on heritable information in the form of DNA
• DNA is the substance of genes.• Genes are the units of inheritance that transmits
information from parents to offspring.
NucleicontainingDNA
Sperm cell
Egg cell
Fertilized eggwith DNA fromboth parents
Embryo’s cells withcopies of inherited DNA
Offspring with traitsinherited fromboth parents
Feedback mechanisms regulate biological systems•Negative Feedback: as more of a
product accumulates, the process that creates is slows and less of the product is produced.•Positive Feedback means that as
more of a product accumulates, the process that creates it speeds up and more of the product is produced.
Excess Dblocks a step
(a) Negative feedback
Negativefeedback
D
D D
D
C
B
A
Enzyme 1
Enzyme 2
Enzyme 3
–
Excess Zstimulates a step
(b) Positive feedback
Z
Positivefeedback
Enzyme 4
Enzyme 5
Enzyme 6Z
Z
Z
Y
X
W
+
Concept 1.2The Core Theme: Evolution accounts for the unity and diversity of life.
“Nothing in biology makes sense except in the light of evolution”—Theodosius Dobzhansky
Organizing the Diversity of Life
•Approximate 1.8 million species have been identified.• Estimates of species that actually exist
from 10 to over 100 million.•Organized in groups: Taxonomy
Species Genus Family Order Class Phylum Kingdom Domain
Ursus americanus(American black bear)
Ursus
Ursidae
Carnivora
Mammalia
Chordata
Animalia
Eukarya
(a) DOMAIN BACTERIA
(b) DOMAIN ARCHAEA
(c) DOMAIN EUKARYA
Protists
Kingdom Fungi
KingdomPlantae
Kingdom Animalia
Thre
e D
omai
n Sy
stem
Unity in the Diversity of Life
•A striking unit underlies the diversity of life:•DNA is the universal genetic
language common to all organisms.•Unity is evident in many features of
cell structure.
Cilia ofParamecium
Cross section of a cilium, as viewedwith an electron microscope
Cilia ofwindpipecells
15 µm 5 µm
0.1 µm
Evolution, Darwin and Natural Selection• Charles Darwin published On
the Origin of Species by Means of Natural Selection in 1859• Darwin made two main points: • Species showed evidence of
“descent with modification” from common ancestors• Natural selection is the
mechanism behind “descent with modification”
Darwin observed that:
• Individuals in a population have traits that vary•Many of these traits are heritable
(passed from parents to offspring)•More offspring are produced than
survive• Competition is inevitable• Species generally suit their environment
Darwin inferred that:
• Individuals that are best suited to their environment are more likely to survive and reproduce• Over time, more individuals in a
population will have the advantageous traits
• In other words, the natural environment “selects” for beneficial traits
Populationwith variedinherited traits.
Eliminationof individualswith certaintraits.
Reproductionof survivors.
Increasingfrequencyof traits that enhance survival and reproductive success.
4321
Darwin proposed that natural selection could cause an ancestral species to give rise to two or more descendent species
COMMONANCESTOR
Warbler finches
Insect-eaters
Seed-eater Bud-eater
Insect-eaters
Tree finches
Green warbler finch Certhidea olivacea
Gray warbler finch Certhidea fusca
Sharp-beakedground finch Geospiza difficilisVegetarian finch Platyspiza crassirostris
Mangrove finch Cactospiza heliobates
Woodpecker finch Cactospiza pallida
Medium tree finch Camarhynchus pauper
Large tree finch Camarhynchus psittacula
Small tree finch Camarhynchus parvulus
Large cactusground finchGeospiza conirostrisCactus ground finchGeospiza scandens
Small ground finchGeospiza fuliginosa
Medium ground finchGeospiza fortis
Large ground finchGeospiza magnirostris
Ground finches
Seed-eaters
Cactus-flower-
eaters
Concept 1.3:Scientists use two main forms of inquiry in their study of nature
• Inquiry is the search for information and explanation•There are two main types of scientific inquiry: discovery science and hypothesis-based science
Discovery Science• This approach is based on
observation and the analysis of data• Data fall into two
categories• Qualitative, or descriptions
rather than measurements• Quantitative, or recorded
measurements, which are sometimes organized into tables and graphs
Inductive Reasoning
• Inductive reasoning draws conclusions through the logical process of induction
• Scientific method…
Observations
Question
Hypothesis #1:Dead batteries
Hypothesis #2:Burnt-out bulb
Test prediction
Hypothesis #1:Dead batteries
Hypothesis #2:Burnt-out bulb
Test prediction
Prediction:Replacing batterieswill fix problem
Prediction:Replacing bulbwill fix problem
Test falsifies hypothesis Test does not falsify hypothesis
Deduction: Logic of Hypothesis Based Science
• Deductive reasoning uses general premises to make specific predictions• For example, if organisms are made of
cells (premise 1), and humans are organisms (premise 2), then humans are composed of cells (deductive prediction)
•A hypothesis must be testable and falsifiable•Failure to falsify a hypothesis does not prove that hypothesis
The Myth of the Scientific Method
• The scientific method is an idealized process of inquiry• Hypothesis-based science is based on the
“textbook” scientific method but rarely follows all the ordered steps• Discovery science has made important
contributions with very little dependence on the so-called scientific method
Limitations of Science
• In science, observations and experimental results must be repeatable• Science cannot support or falsify
supernatural explanations, which are outside the bounds of science