Van Roekel
IB BIO II
4/14/14
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Used to calculate frequencies of alleles,
genotypes, or phenotypes within a population
Useful in determining how fast a population
is changing or in predicting the outcomes of
matings or crossings.
Based off of Punnett squares and probabilities
to model allele and genotype frequencies
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When looked at individually, the frequencies
of alleles on chromosomes must add up to 1
p+q=1
p = frequency of dominant allele
q = frequency of recessive allele
p = 0.5
q = 0.5
T
t
T
TT
Tt
t
Tt
tt
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We are interested in diploid organisms that
carry two copies of any trait, so…
(p+q)2 = 1
p2 + 2pq + q2 = 1
p2 = frequency of homozygous dominant
q2 = frequency of homozygous recessive
2pq = frequency of heterozygote
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TT = p2 = ¼
tt = q2 = ¼
Tt = 2pq = ½
p2 + 2pq + q2 = 1
¼ + ½ +1/4 = 1
T
t
T
TT
Tt
t
Tt
tt
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What is the Hardy-Weinberg Equation and what does
each variable represent? What does this equation tell us?
 (p+q)2 = 1, or p2 + 2pq + q2 = 1
 p2 = homozygous dominant frequency
 q2 = homozygous recessive frequency
2pq = heterozygous frequency
 p = dominant allele frequency
 q = recessive allele frequency
Used to calculate frequencies of alleles, genotypes, or
phenotypes within a population
Useful in determining how fast a population is changing
or in predicting the outcomes of matings or crossings
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Populations being studies must be a large
population, ideally infinite
Random mating between individuals with the
particular alleles being examined, aka the trait is
autosomal
There must be a constant allele frequency over
time
There is no allele specific mortality (sickle cell
anemia)
There are no mutations that could introduce new
alleles
There is no emigration or immigration which
would alter allele frequency
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Consider a disease caused by a recessive
allele t. The predicted allele frequency in a
population in 10%, what is the frequency of
the healthy allele in the population?
Answer: 90%
p+q=1
1-q = p
1-.10 = .90
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A study examined 989 members of the
previous population, it was found that 11
people had the disease. Calculate the allele
frequency of the recessive allele t.
Answer: 10.5%
11/989 = .011 = q2 = genotype frequency
Square root of .011 = 0.105 = 10.5% = q
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Calculate the allele frequencies and genotype
frequencies of the population in example 1.
Calculate the number of carriers in 500
members of the population
Allele Frequencies: q = 0.10 or 10%
p= 0.90 or 90%
Genotype Frequencies: q2 = .01 or 1%
2pq= 0.18 or 18%
p2 = 0.81 or 81%
Carriers = 90 people (500 x 18%)
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Using information from example 3, calculate
the number of people in 500 members that
do not suffer from the disease.
Answer: 495 people
p2 + 2pq = 81% + 18% = 99%
99% x 500 = 495
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Use binomial nomenclature to name and classify
organisms
1st word refers to the genus, 2nd word to the
species, i.e. Homo Sapiens.
Carolus (Carl) Linnaeus consolidated and
popularized binomial nomenclature
Reasons:
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Make sense of biosphere
Identify unknown organisms
Show evolutionary links
Predict characteristics shared by members of a group
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Five Kingdoms
◦ Kingdom Plantae (plants)
◦ Kingdom Animalia (animals)
◦ Kingdom Fungi (fungi and molds)
◦ Kingdom Protoctista (protozoa and algae)
◦ Kingdom Prokaryote (bacteria)
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Within each kingdom, there are several
subdivisions, called taxa
Seven-level hierarchy of taxa:
◦ Kingdom
◦ Phylum
◦ Class
◦ Order
◦ Family
◦ Genus
◦ Species
King Phillip Came Over For Good Soup
Taxa
Human
Garden Pea
Kingdom
Animalia
Plantae
Phylum
Chordata
Angiospermae
Class
Mammalia
Dicotyledoneae
Order
Primate
Rosales
Family
Hominidae
Papilionaceae
Genus
Homo
Pisum
Species
sapiens
sativum
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Feeding Habits (carnivore/herbivore)
Habitat (land dwelling/aquatic)
Daily activity (nocturnal/diurnal)
Risk (harmless/venomous)
Anatomy (vertebrates/invertebrates)
System of classification must be clear,
consistent, easily implemented and a general
consensus to apply it.
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Four of the several types of plant phyla
include:
◦ Bryophyta: short in stature such as moss
◦ Filicinophyta: ferns and horsetails
◦ Coniferophyta: coniferous, pine trees
cedar, juniper, fir
◦ Angiospermophyta: all plants that make
flowers and have seeds surrounded by
fruit
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Vegetative Characteristics such as leave types
and stems
◦ Bryophytes: non-vascular, lack vascular
transport tissue such as xylem or phloem
◦ Filicinophyta: vascular plants, small leaves
◦ Conifers: vascular, all produce woody
stems and leaves are needles or scales
◦ Angiosperms: vascular and have flowers
and fruit
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Reproductive characteristics
◦ Bryophytes: produce spores (microscopic
reproductive structures) transported by rain
water
◦ Filicinophytes: produce using spores in a
similar manner
◦ Conifer: use wind to help reproduce by
pollination, produce seed cones with seed
scales
◦ Angiosperms: produce seeds, rely on birds,
insects, and mammals to transport pollen.
Sexual organ is flower, fruit is enlarged ovary
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Six of many animal phyla include:
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All listed phyla are invertebrates
◦ Proifera: sponges
◦ Cnidaria: sea jellies (jellyfish), coral
polyps, and others
◦ Platyhelminthes: flatworms
◦ Annelida: segmented worms
◦ Mollusca: snails, clams, octopi, etc…
◦ Atrhtropoda: insects, spiders, crustaceans,
etc…
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Porifera:
◦ Simple marina animals that are sessile (stuck)
◦ Feed by pumping water through tissues and
filtering out food
◦ No muscle, nerve tissues, or internal organs
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Cnidaria:
◦ Very Diverse: Coaral, sea anamones, jellyfish,
hydra, Portuguese man-of-war
◦ All have stinging cells called nematocysts
◦ Some sessile, some free swimming, some both
◦ Gastric pouch for digestion
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Platyhelminthes:
◦ Flatworms with one body cavity, gut with one
opening for food to enter and waste to leave
◦ No heart, no lungs
◦ Exchange gas by diffusion
◦ Example: Tapeworms
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Annelida:
◦ Segmented worms such as earthworms, leeches,
and polychaetes
◦ Bodies divided into sections separated by rings
◦ Have gastric tracts, w/ mouth at one end and anus
at opposite
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Mollusca:
◦ Aquatic animals, snails, clams, octopi
◦ Shell produced with calcium
◦ Non-segmented bodies
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Arthropoda:
◦ Hard exoskeleton made with chitin, segmented
bodies, and limbs (walking, swimming, eating)
◦ Insects, spiders, scorpions, crustaceans such as
crab and shrimp
◦ Live in most habitats throughout world
◦ Vary in size
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Used to help identify which order, genus, and species an
organism is by using observable characteristics
In General:
◦ Look at first section of key which has a pair of
sentences
◦ Look at the organism to see if particular
characteristics are present
◦ If answer is yes, to go end of line/next section that
contain a new pair of statements to examine
◦ If answer is no, go to second statement just below it
and follow that one, should it be true
◦ Continue this until the end of the line has a name, not
a number and if each question was answered
correctly, should be your organism.
Example in book, pg. 149
1. a. Organism is living........................................................go to 4.
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1. b. Organism is nonliving..................................................go to 2.
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2. a. Object is metallic........................................................go to 3.
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2. b. Object is nonmetallic..................................................ROCK.
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3. a. Object has wheels......................................................BICYCLE.
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3. b. Object does not have wheels......................................TIN CAN.
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4. a. Organism is microscopic...................................PARAMECIUM.
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4. b. Organism is macroscopic............................................go to 5.
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5. a. Organism is a plant.....................................................go to 6.
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5. b. Organism is an animal.................................................go to 8.
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6. a. Plant has a woody stem..............................................go to 7.
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6. b. Plant has a herbaceous stem.................................DANDELION.
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7. a. Tree has needle like leaves.....................................PINE TREE.
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7. b. Tree has broad leaves............................................OAK TREE.
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8. a. Organism lives on land................................................go to 9.
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8. b. Organism lives in water...............................................CLAM.
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9. a. Organism has 4 legs or fewer......................................go to 10.
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9. b. Organism has more than 4 legs...................................ANT.
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10 a. Organism has fur........................................................go to 11.
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10 b. Organism has feathers................................................ROBIN.
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11 a. Organism has hooves.................................................DEER.
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11 b. Organism has no hooves............................................MOUSE.
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Vocabulary can be challenging and technical
Make sure using the right key, no key can
identify all the species
Making a Dichotomous Key
◦ Start by putting things in groups by identical
characteristics
◦ Invent statements that divide things into created
groups