Transcript Homework/Class Work

Tuesday 2/10/2015
Agenda: Evolution Part II
 Notes: Rates of Evolution and Radioactive Decay
 Activity: Modeling Radioactive Decay
Homework/Class Work:
Radioactive Dating Practice Worksheet due
Wednesday/Thursday 2/11-2/12/2015 for 21 Points
Q3 WK4 D4&5
The Rate of Evolution
Different kinds of organisms evolve at
different rates
Bacteria evolve much faster than complex cells
The rate of evolution also differs within the same
group of species
In punctuated equilibrium, evolution occurs in
spurts
In gradualism, evolution occurs in a gradual,
uniform way
Punctuated equilibrium
Gradualism
GRADULISM
PUNCTUATED
EQUILIBRIUM
Evidence of Evolution
1. Fossil Records
2. Molecular Records (Carbon Dating and DNA)
3. Anatomical Records
Fossil Records
Fossils are the preserved remains, tracks, or traces
of once-living organisms
Fossils form when organisms become buried in
sediment and calcium in hard surfaces mineralizes
Arranging fossils according to age often provides
evidence of successive evolutionary change
Robert Hooke in 1668- 1st to propose that fossils
are the remains of plants & animals.
Provides the most direct evidence for
macroevolution
Missing Links
Ardi (Ardipithecus ramidus) : stood about 47
inches tall and weighed about 110 pounds.
Took 15 years to unearth.
Lived 4.4 million years ago
Lucy (Australopithecus afarensis) : 40 % complete skeleton.
Lived 3.2 million years ago
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Fossils have been
found linking all
the major groups
The forms linking
mammals to
reptiles are
particularly well
known
Fig. 13.4 Whale
“missing links”
More Missing
Links
Archaeopteryx. The most primitive known
bird. Lived ~150 million years ago.
Ambulocetus: The walking
whale. This animal could walk
as well as swim. It lived ~50
million years ago.
Fossil Records
• Relative Dating (aka Law of
Superposition) by Nicolaus
Steno
• By looking at where the
fossils are in relation to the
rock depth or layers,
scientists can see when an
organism goes extinct or
when there is a mass
extinction
• In other words, in a cross
section of the Earth or rock
layers, the lowest layer is the
oldest
Molecular Records
• Certain atoms are known to decay (break down) at a
specific rate. Scientists can look at these atoms to
determine how old an organic object is.
• Radioactive isotope 14C- gradually decays over time back to
14N (known as Carbon Dating)
• It takes 5600 years for half of the 14C present in a sample to be
converted to 14N.
• This length of time is called the half-life.
• Half life (t1/2): the time needed for half of the atoms of
the isotope to decay
• For fossils older than 50,000 yrs scientists use potassium
isotope
• t1/2 of 40K = 1.3 billion years to turn to argon (40Ar)
How do we use the method?
Uranium-235 has a half-life of 700 million years. How much of the 12 g sample of
Uranium-235 will be left after:
• a. 700 million years _______
• b. 1400 million years _______
Modeling Radioactive Decay
• Each student needs a textbook; page. 253.
• Follow the procedures #1-8
• Each table will get 1 bag of 100 dried corn kernels & 1
plate / bowl
• Each student must complete & turn in a sheet
with the completed data table & graph
Radioactive Dating
Practice worksheet
• Lets practice radioactive dating
• Attach into your sci. ntbk 
Wednesday/Thursday 2/11-2/12/2015
Agenda: Evolution
 Notes: Anatomical Records and Structures
 Activity: Structures Foldable
 Activity: Iceman Murder Mystery
Homework/Class Work:
 No Homework Tonight!
Radioactive Dating
Practice
Lets practice radioactive dating to better understand the homework:
How much of 20.0 grams of a substance will be left after 1 hour if the half life is
15 minutes (answer in grams)
The half life of thorium-27 is 16.32 days. How many days are required for 2.63 to
remain if you start with 84.25 grams?
Reading & Organizer
Anatomical Record:
Informational Text
• What is informational text?
• What is its purpose?
• Why would informational text be vital for
science?
• Is informational text necessary when discussing
evolution?
Anatomical Record

Similar structural forms can be seen in
different living organisms
3.
Homologous structures
Analogous structures
Vestigial structures

All vertebrates share a basic set of developmental instructions
1.
2.
Relict
developmental
forms

Homologous structures: have same structure,
DIFFERENT function. However, the structures
are derived from the same part of a common
ancestor
The same basic bones
are present in each
forelimb
Fig. 13.8
Homology among
vertebrate limbs

Analogous structures: resemble each other as a
result of needed adaptations to similar
environments (Different animals adapt in similar
fashion when challenged by similar opportunities)
 The feature has the same function but looks
different.

Vestigial structures:
 Although the structure(s) had a purpose &
function in the past but they are largely or
entirely functionless now.
 a vestigial structure may retain lesser
functions or develop new ones.
The blue whale has tiny hind leg bones under its tail.
The blind mole rat has tiny eyes completely
covered by a layer of skin.
Friday 2/13/2015
Agenda: Evolution
 Notes: Conclusion of Evolution Part II Notes
 Activity: Evolution Part II Worksheet
Homework/Class Work:
 Evolution Part II Worksheet due Tuesday 2/17/2015
for 20 Points
Everyone must complete EACH station
Station 1: Homologous Structures- Read Handout, EVERYONE must complete the
coloring sheet and Animal / Function chart. Fill out the chart on the BACK of the
coloring sheet
Station 2: Analogous Structures. EVERYONE completes this on the “Summary Sheet.”
Station 3: Vestigial Structures. EVERYONE completes this on the “Summary Sheet.”
Station 4: Evolution of the Horse. Answer questions on a separate sheet of paper.
EVERYONE WRITE & ANSWER
Station 5: Vestigial Structures (Part II). Answer questions on a separate sheet of paper.
EVERYONE WRITE & ANSWER
Station 6: Embryo Evidence. EVERYONE WRITE & ANSWER! Answer questions on BACK
of paper you glue embryos on.
Q3 WK7 D1
PATTERNS OF EVOLUTION
Coevolution: Change of two or more
species in close association with each
other. Dependency develops
EXAMPLE:
Bumblebees and the
flowers they pollinate
have co-evolved so that
both have become
dependent on each other
for survival.
Convergent Evolution: A kind of evolution where
an organism develops structures that have similar
(analogous) structures or functions regardless of their
evolutionary ancestors being very dissimilar or
unrelated.
Analogous structures are the result of convergent evolution.
DIVERGENT EVOLUTION: 2 or
more related species that become
more dissimilar due to different
environments.
•This usually produces another species
EXAMPLE:
GALAPAGOS
FINCHES
Notebook Check
• Warm-Ups: 1/18, 1/22, 1/23 or 1/24, 1/25, 1/28,
1/29 or 1/30, 1/31 or 2/1
• Notes: Rate of Evolution
• Activities: Theory Comparison worksheet, 10
Examples of Natural Selection questions, Darwin’s
Natural Selection worksheet
EVOLUTIONARY FORCES

5 evolutionary forces can significantly
alter the allele(s) frequencies of a
population




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1.
2.
3.
4.
5.
Mutation
Migration
Genetic drift
Nonrandom mating
Selection
Mutation



The MAIN source
of new variation
Errors in DNA
replication and
change in DNA due
to extraneous
factors
Mutation rates are
too low to
significantly alter
allele frequencies on
their own
Migration

Movement of individuals from one population to
another

Immigration: movement INTO a population

Emigration: movement OUT of a population
A very
potent
agent of
change
Genetic Drift
A. Random loss of alleles

More likely to occur in
smaller population
B. Founder effect

Small group of
individuals establishes
a population in a new
location
C. Bottleneck effect

A sudden decrease in
population size to
natural forces
Mating that occurs
more or less frequently
than expected by
chance
 Inbreeding
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Mating with relatives or self
Increases homozygosity
Outbreeding


Mating with nonrelatives
Increases
heterozygosity
Nonrandom Mating
Selection
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Some individuals leave
behind more offspring
than others
Artificial selection


Creating unnatural
characteristics by
breeding species to
promote a certain type
of offspring.
Natural selection

Environment selects for
adapted characteristics
Jack Russell + Mini Italian
Greyhound = Guapo 
End: Q3 WK5 D2