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AP Biology Exam Review

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Title: AP Biology Exam Review


1
AP Biology Exam Review
  • Heredity and Evolution 25

2
Evolutionary biology 8
  • Early evolution of life
  • Evidence of evolution
  • Mechanisms of evolution

3
Related fields of study
  • Paleontology study of fossils
  • Comparative anatomy study of structural
    similarities among organisms
  • Comparative embryology study of embryological
    similarities among organisms
  • Taxonomy study of organism groupings with
    similar homologous structures (including
    vestigial organs)
  • Biochemistry chemical reactions in living things

4
Terminology
  • Population localized group of individuals of the
    same species
  • Species group of population whose individuals
    have the potential to interbreed and produce
    fertile offspring
  • Gene pool total aggregate of all genes in a
    population at any given time

5
Tenets of evolution
  • Natural selection edits the available gene pool
    for a species.
  • Natural selection is contingent upon time and
    place. Certain variations in a population (group
    of species residing in one area) are more favored
    for survival than others.
  • Mutations are a sources of variation in a
    population.
  • Descent with modification

6
DDT Insects
  • Insects with DDT resistance also have reduced
    metabolism.
  • Without DDT present, these insects are not
    adapted for the environment.

7
Homology vs. Analogy
8
Three kinds of homologies having common origin
  • 1. Anatomical homology example, forelimbs
  • 2. Embryological homology example, Eustachian
    tube in humans and all mammals
  • 3. Molecular homology DNA, RNA as genetic code
    (shown through RFLP analysis)

9
Molecular homology
  • Human hemoglobin has 146 amino acids total.

10
Sugar glider vs. Flying squirrel
Convergent evolution
11
Genetic drift
Changes to allele frequencies in population due
to random chance
12
Bottleneck effect
  • Genetic drift due to drastic reduction in allele
    frequencies

What factors can cause bottleneck effect?
13
The founder effect
  • Members from a larger population colonize an
    isolated region. (Ex primary, secondary
    succession)
  • Ex 15 people founded a British colony in 1814,
    midway in the Atlantic Ocean. One colonist had
    retinitis pigmentosa, a recessive degenerative
    blindness. Today, there is a higher frequency of
    this disorder than most places on Earth.

14
Gene flow
  • Genetic exchange due to migration of fertile
    individuals or gametes between populations
  • Ex wind carrying pollen grains with sperm from
    plant to far off locations

15
Mutations
  • Changes to an organisms DNA
  • Changes in the DNA, if occurring in gametes, can
    be passed down to the next generation.
  • Quantitative changes to the population can only
    result if organisms with the mutation produce a
    disproportionate number of offspring.

16
Variations in the population
  • Polymorphism For any characteristic, there are
    more than two morphs (forms).
  • A variation of the characteristic can only be
    considered one of the morphs if there is a high
    enough frequency in the population.

17
Measuring diversity
  • Gene diversity measuring whole gene differences
  • Nucleotide diversity measuring differences at
    the molecular level (using RFLP analysis or
    genomic comparisons)

18
Geographic diversity
  • Differences in gene pools between populations or
    within subgroups of populations
  • Cline graded change in some trait along a
    geographic axis

19
Cline
20
What preserves variation
  • Mutation
  • Sexual recombination (meiosis)
  • Diploidy
  • Balanced polymorphism ability to maintain stable
    allele frequency (established through
    heterozygote advantage and frequency-dependent
    selection)
  • Neutral variation

21
Directional selection
22
Limitations of natural selection
  • 1. Limited to historical constraints
  • 2. Adaptations are often compromises.
  • 3. Not all evolution is adaptive.
  • 4. Selection can only edit existing variations.

23
Hardy-Weinberg equation of non-evolution
  • No natural selection
  • No mutation
  • No migration
  • Large population
  • Random mating
  • p2 2pq q2 1
  • p q 1

24
Hardy-Weinberg equation
  • p frequency of dominant allele in the
    population (A)
  • q frequency of recessive allele in the
    population
  • p2 AA (homozygous dominant genotype)
  • 2pq Aa (heterozygous genotype)
  • q2 aa (homozygous recessive genotype)
  • p2 2pq dominant phenotype
  • q2 recessive phenotype

25
Sample H-W problem
  • Hint to solving these equations LOOK FOR THE
    PERFECT SQUARE!! SOLVE FOR Q!
  • In a population of 100 individuals, 91 in the
    population show the dominant phenotype. What is
    the frequency of the dominant allele in this
    population?
  • (100 91)/100 recessive phenotype q2
  • .09 q2 q .3 pq 1 p .7

26
The Origin of Species
  • In what circumstances would new species evolve
    from preexisting species?

27
Reproductive barriers helps to preserve species.
  • Any factors that impedes the reproduction of
    members within a species
  • Without the ability to breed together, the gene
    pool is isolated. (no migration)

28
Two types of barriers
  • Prezygotic barriers prevents fertilization of
    ova (egg)
  • Postzygotic barriers following fertilization,
    hybrid zygote unable to develop into viable
    offspring

29
Prezygotic barriers
  • Habitat isolation
  • Behavioral isolation
  • Temporal isolation
  • Mechanical isolation
  • Gametic isolation

30
Postzygotic barriers
  • Reduced hybrid viability
  • Reduced hybrid fertility
  • Hybrid breakdown

31
Other definition of species
  • Ecological niche (set of environmental resources
    an organism uses)
  • Pluralistic more than one way to define species
  • Morphological organisms with unique set of
    structural features
  • Geneological organisms with unique genetic
    history

32
Interrupting gene flow
  • Changes to the gene pool can ultimately lead to
    evolution of new species.
  • This is called speciation.

33
Patterns of speciation
  • Anagenesis phyletic evolution, accumulation of
    heritable change in a population
  • Cladogenesis branching evolution, (basis for
    biological diversity)

34
Three modes of speciation
  • Allopatric speciation geographic separation
    leads to new species if organisms evolve
    reproductive barriers
  • Sympatric speciation small population within
    parent population becomes new species
  • Adaptive radiation ancestral species colonize an
    area where diverse geographic or ecological
    conditions are available, rapid evolution

35
Allopatric vs. Sympatric
  • What factors can lead to each type of speciation?

36
Allopatric speciation
  • Geographic barriers (mountains, valleys, etc) can
    separate the ability for breeding between members
    of the same species.
  • Ring species species that seemingly are in the
    gradual process of divergence from a common
    ancestor

37
Adaptive radiation
  • Much like allopatric speciation
  • Island chains have geographic isolation but are
    close enough for occasional have hybrids between
    populations.

38
How reproductive barriers evolve
  • Diane Dodds experiment showing allopatric
    speciation leading to reproductive barrier
    (therefore new species)

39
Allopatric speciation
40
Sympatric speciation in plants
  • Autopolyploid organism with more than normal
    chromosome due to meiotic failures.
  • 4N can breed with 4N ? 8N offspring (polyploid)
  • In one generation, postzygotic barriers form,
    causing reproductive isolation.

41
Allopolyploid
  • Members of two different species create a hybrid
    that cannot back breed with parents. The hybrid
    is more vigorous (hybrid vigor) enables hybrid
    to reproduce asexually ? may eventually evolve
    sexual reproduction.

42
Sympatric speciation
  • Fishes in Lake Victoria (East Africa) demonstrate
    that females may select mates based on
    coloration.
  • Overtime, the nonrandom mating leads to
    behavioral isolation, and a new species of fish
    arise within the parental population.

43
Punctuated equilibrium
  • Sudden appearance of organisms in the
    phylogenetic tree

44
Micro vs. Macroevolution
  • Microevolution changes in gene (allelic)
    frequency over generations Hardy Weinberg
  • Macroevolution level of change in organisms that
    is evident in the fossil record (requires long
    period of time)
  • Speciation bridges microevolution and
    macroevolution.

45
Patterns of evolution
  • Divergent evolution Two or more species
    originate from the same ancestral species.
  • Convergent evolution Two unrelated species share
    many characteristics.
  • Parallel evolution Two related species after
    divergence evolve similar characteristics.
  • Coevolution symbiotic relationships

46
Origin of life
  • Oldest fossils 3.5 billion years old,
    indicating maybe oldest life form 1 billion years
    old
  • Cyanobacteria earliest fossilized organisms
  • Common metabolic pathway in all organisms
    glycolysis
  • Primitive atmosphere hydrogen, methane, ammonia,
    water vapor (reducing atmosphere)

47
Chemical evolution
  • 1. Earth and its atmosphere formed.
  • 2. Primordial seas formed.
  • 3. Complex molecules synthesized.
  • 4. Polymers and self-replicating molecules were
    synthesized. (proteinoids)
  • 5. Organic molecules were concentrated and
    isoaltred into protobionts.
  • 6. Primitive heterotrophic prokaryotes formed.
  • 7. Primitive autotrophic prokaryotes formed.
  • 8. Oxygen and ozone layer formed.
  • 9. Eukaryotes formed.

48
Endosymbiotic theory
  • Mitochondria and chloroplast have their own
    circular and naked DNA.
  • M C ribosomes similar to bacteria.
  • M C divide independently much like binary
    fission.
  • Thylakoid membranes of chloroplast resemble
    membranes of cyanobacteria.

49
Origin of life experiments
  • Oparin and Haldane able to produce coacervates
    that could take in enzymes predicted simple
    molecules form when oxygen absent
  • Stanley Miller able to synthesize simple organic
    compounds with flash of electricity
    (lightning) tested Oparin and Haldanes
    hypotheses
  • Melvin Calvin complex molecules formed from
    polymerization
  • Sidney Fox microspheres (protenoids)

50
Chemical selection
  • Aggregates with most stable compounds remained.
  • Chemical reactions that preserved aggregates
    enabled aggregates to remain.
  • Nonliving ? living able to store and use energy
    (metabolism), able to pass on genetic information

51
Hydrogen pumps
  • Believed to be the first enzymatic proteins
    (light-driven) to provide coacervate energy
  • ETC of respiration and photosynthesis formed

52
Why RNA before DNA
  • RNA has extra OH group on 2 carbon.
  • It is able to bind amino acids to allow for
    translation (genetic material ? protein enzymes)

53
Earliest organisms
  • May have been heterotrophs
  • As O2 generated in atmosphere from
    photodissociation (H2O)
  • H2O2 may have formed ? killing off heterotrophs
  • Cyanobacteria increased in gene pool, forming
    ozone layer.
  • Aerobic respiration may have evolved.
  • Heterotroph-autotroph hypothesis
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