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Lecture 2

BIO SCI 1A Lecture Notes - Lecture 2: Paleozoic, Cambrian Explosion, Radioactive Decay

Biological Sciences
Course Code
Richard Symanski

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species that mutually influence each others evolution
Going on for more than 100 million years
Result: flower structures have become incredibly diverse and complex
What Animals Do
Birds bees ants flies _ visit flowers to get pollen or nectar
Nectar is a saccharine secretion of plants to attract animals.
Birds and others then carry pollen from one flower or plant to another
RESULT: Carriers contribute to genetic diversity of plant population
Products of Coevolution
Can be quite specific
Some yucca plants pollinated by only one kind of moth
BUT: most plant-pollinator interactions less specific
Same animals pollinate many species
Different animals pollinate the same species
Think of These Concepts When Watching FILM
Adaptation Strategy Deception/decent Cheating
Advertising, Beauty, Coevolution, Timing
Organisms plants and animals (the latter excepting humans) do not
plant or think about or design to be deceptive or attractive
or to cheat
RATHER, those organisms that evolve
In some time, plants need death to secure a new generation
Flower is sex organ
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Further problems with system
Need to reflect genealogical relations, not just similarity in
Goal of taxonomy became: reflect Phylogeny – tribe source
- True historical relationships among organisms
- Came up with phylogenic tree: expresses relationships among
- Branches closest to one another represent species most closely
Some particulars to remember
Panther LEO (Genus Panther; LEO LION)
Note: Both italicized
Note: Genera capitalized, species small case
Classification in General
Classification system in general.
Jorge Luis Borges and a  certain Chinese encyclopedia
To Note About Encyclopedia
It is classes are not exclusive
The scheme includes categories that attack logical structure of every
list. Thus, the worst of all possible classification schemes
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What is a gene?
Basic unit of inheritance
Sequence of hereditary information of DNA (deoxyribonucleic acid)
What is an allele?
Form of a gene
May be two or more forms of a gene
An allele is a form of a gene (eye color controlled by approx., 6 genes,
all with multiple alleles, but is usually portrayed as 1 gene with 2
alleles: B and b)
Allele frequency: the percentage of a particular allele in a population
Genotype: the genetic basis of a trait
Phenotype: the appearance of a trait
Human Eye Color
B confers brown, b confers blue, and B is dominant
Assume that a population has following genotype frequency:
50% BB
30% Bb
20% bb
What is the frequency of eye color phenotypes if the genotype frequency
is 50% BB, 30%Bb, and 20% bb?
Difference between:
- Genotype frequency
- Phenotype frequency
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