Post on 20-Jan-2016
Figure 1.1 Life’s Calendar
Origin of Life
Oldest fossils
Photo-synthesis evolves
Eukaryotic cells evolve
Multi-cellular organisms
Abundant fossils of aquatic life
First land plants
First land animals
Coal-forming forests
Insects abundant
First mammals
Dinosaurs dominant
First birds
First flowering plants
Rise of mammals
First hominids
Figure 1.2 The Basic Unit of Life Is the Cell
Haloferax mediterranei Membrane
Figure 1.4 The Tree of Life
Life
Plants
Protists
Protists
Protists
Protists
Protists
Protists
Animals
Fungi
10,000
260
270,000
80,000
1,300,000
98,000
1,000–1 million
400,000–500,000
500,000–1 million
10 million–100 million
1–2 million
MillionsBACTERIA
ARCHAEA
EUKARYA
Mito
ch
on
dri a
Ch
l oro
pl a
sts
Number of known (described)
species
Estimated total number of living
species
Figure 1.5 DNA Is Life’s Blueprint
One nucleotide
DNA
Gene
DNA
Protein
Figure 1.6 Biology Is Studied at Many Levels of Organization (Part 1)
(A) Atoms to organisms
Atoms
Oxygen
Carbon
Hydrogen
Water
Small molecules
Methane
Carbon dioxide
Large molecules, proteins, nucleic acids
Cells
Colonial organisms
Unicellular organisms
Cell specialization
Tissues
Organs
Organs systemsMulticellular organism
(leopard frog)
Organism
Figure 1.6 Biology Is Studied at Many Levels of Organization (Part 2)
(B) Organisms to ecosystemsEcosystem
PopulationCommunity
Biosphere
Figure 1.7 Adaptations to the Environment (Part 1)
(A) Dyscophus guineti
Figure 1.7 Adaptations to the Environment (Part 2)
(B) Xenopus laevis
Figure 1.7 Adaptations to the Environment (Part 3)
(C) Agalychnis callidryas
Figure 1.7 Adaptations to the Environment (Part 4)
(D) Rhacophorus nigropalmatus
Figure 1.8 Scientific Methodology
1. Make observations.
2. Speculate, ask a question.
3. Form a hypothesis to answer the question.
4. Make a prediction: What else would be true if your hypothesis is correct?
5. Design and conduct an experiment that uses quantifiable data to test your prediction.
Use statistical tests to evaluate the significance of your results.
Significant results support hypothesis.
Results do not support hypothesis.
Experiment repeated and results verified by other researchers.
Reexamine the experiment for uncontrolled variables.
Revise your hypothesis.
Ask new questions.
Figure 1.9 Controlled Experiments Manipulate a Variable (Part 1)
Exposure to atrazine during larval development causes abnormalities in the reproductive tissues of male frogs.
1. Establish 9 tanks in which all attributes are held constant except the water’s atrazine concentration. Establish 3 atrazine conditions (3 replicate tanks per condition): 0 ppb (control condition), 0.1 ppb, and 25 ppb.
2. Place Rana pipiens tadpoles from laboratory-reared eggs in the 9 tanks (30 tadpoles per replicate).
3. When tadpoles have transitioned into adults, sacrifice the animals and evaluate their reproductive tissues.
4. Test for correlation of degree of atrazine exposure with the presence of abnormalities in the gonads (testes) of male frogs.
Figure 1.9 Controlled Experiments Manipulate a Variable (Part 2)
Oocytes (eggs) in normal-sized testis (sex reversal)
Atrophied testes
Testicular oogenesis
Ma
le f
rog
s
wit
h g
on
ad
al
ab
no
rma
liti
es
(%
)
Atrazine (ppb)Control
Exposure to atrazine at concentrations as low as 0.1 ppbinduces abnormalities in the gonads of male frogs. The effect is not proportional to the level of exposure.
Figure 1.10 Comparative Experiments Look for Differences among Groups (Part 1)
Presence of the herbicide atrazine in environmental water correlates with gonadal abnormalities in frog populations.
1. Based on commercial sales of atrazine, select 4 sites (sites 1–4) less likely and 4 sites (sites 5–8) more likely to be contaminated with atrazine.
2. Visit all sites in the spring (i.e., when frogs have transitioned from tadpoles into adults); collect frogs and water samples.
3. In the laboratory, sacrifice frogs and examine their reproductive tissues, documenting abnormalities.
4. Analyze the water samples for atrazine concentration (the sample for site 7 was not tested).
5. Quantify and correlate the incidence of reproductive abnormalities with environmental atrazine concentrations.
Figure 1.10 Comparative Experiments Look for Differences among Groups (Part 2)
Atrophied testes
Testicular oogenesis
Atrazine level
Atra
zine
(pp
b)
Ma
le f
rog
s w
ith
go
na
da
l a
bn
orm
ali
tie
s (
%)
Reproductive abnormalities exist in frogs from environments in which aqueous atrazine concentration is 0.2 ppb or above. The incidence of abnormalities does not appear to be proportional to atrazine concentration at the time of transition to adulthood.
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