Biology Exam 1 2
Terms
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copy deck
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You are part of an archeological expedition to unearth the remains of an ancient
monastery in Egypt. Historical documents give the age of the monastery as
approximately 700 years old. You need physical evidence to support this claim.
As pa -
No. The evidence suggests the bowl is about 2850 years old (about 2000 years older than
the historical documents suggest the monastery is). The age of 2850 is found by
multiplying 5700 by .5 (75% is .5 half-lives). -
Darwin’s examination of fossils relied on __________ dating to determine the
evolution of species. - Relative
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A paleontologist estimates that when a particular rock formed, it contained 36 mg
of the radioactive isotope potassium-40. The rock now contains 4.5 mg of
potassium-40. The half-life of potassium-40 is 1.3 billion years. About how old
is t - The rock is approximately 3.9 billion years old (3 half-lives old).
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In some breeds of dogs, progressive retinal atrophy (PRA) is inherited as an autosomal
recessive disorder and causes blindness. Two dogs that are carriers of the PRA allele but have
normal vision are mated and have a litter of puppies. What pro -
½ x ½ = 1/4 will be afflicted
1-1/4=3/4 will not be afflicted -
In humans, albinism is caused by a single gene. A homozygous recessive individual (aa) will
not have skin pigmentation. Ann is albino. Her husband Mike is not albino. They have two
children, Sarah (who has skin pigmentation) and Martha (who is -
Answer: Ann = aa, Mike = Aa, Sarah =Aa, Martha = aa
b) What is the probability that their next child will be an albino?
Answer: 50%
c) If Ann remarries and has five more children, all with normal pigmentation, what is
most likely the genotype of her new husband?
Answer: He is most likely AA
d) If Ann remarries a man who is heterozygous for albinism, what is the probability that
her second family will have three children that are pigmented and one child that is albino.
Answer: 4/16 or 1/4
Three step solution:
First, how many different ways can birth order fulfill the conditions? Or how many ways
can you arrange 3 and 1?
PPPA
APPP
PAPP
PPAP
Second, The individual probability of each possible arrangement= ½ x ½ x ½ x ½ =1/16
Third, add the probabilities (i.e., Rule of addition)=4/16=1/4 -
Given two separate, independently assorting genes, A and B, with A dominant to a and B
dominant to b, answer the following questions:
a) What is the probability of getting an AB gamete from an individual who is
heterozygous at both loci? -
a) What is the probability of getting an AB gamete from an individual who is
heterozygous at both loci?
Answer: ½ x ½= ¼
b) What is the probability of getting an Ab gamete from an individual who is
heterozygous at both loci?
Answer: ½ x / ½ = ¼
c) What is the probability of getting an AB gamete from an individual who is AABb?
Answer: 1 x ½=1/2
d) What is the probability of getting an AABB child from a cross of two people
heterozygous at both loci?
Answer: (From part a prob(AB) = 1/2 x ½=1/4) so pro(AABB) = ¼ x ¼=1/16
e) From a cross of two people heterozygous at both loci, what is the probability of having
a child that expresses the dominant phenotype for both loci?
Answer: ¾ x ¾ = 9/16 - A phenotypic ratio of 1:2:1 in the F2 generation of a monohybrid cross is best explained by:
- incomplete dominance
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If a plant of genotype AaBbCcDd is selfed and the genes assort independently, how many
different genotypes will be found among the progeny? - 81
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If 2 mice of genotype FfGgHhIiJj are repeatedly mated, and the genes assort
independently, how many different phenotypes will be found in the progeny? - 32
-
In a cross between a female AaBbccDdee and a male AabbCcDdee, what proportion of
the progeny will be phenotypically identical to the female parent? (Assume independent
assortment of all genes and complete dominance). - 9/64
- a single gene has effects on several aspects of an organism’s phenotype
- pleiotropy
- more than one gene affects one aspect of an organism’s phenotype
- polygenic effect
- List five reasons why simple Mendelian inheritance is often NOT observed for most traits.
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Incomplete dominance, codominance, polygenic inheritance, pleiotropy, epistasis, environmental
effects -
3. Blood must be ‘typed’ before patients can be transfused or given blood. This is because
individuals with the A allele add the sugar galactosamine to the surface of their red blood cells
while individuals with the B allele add a different -
3. Blood must be ‘typed’ before patients can be transfused or given blood. This is because
individuals with the A allele add the sugar galactosamine to the surface of their red blood cells
while individuals with the B allele add a different sugar, galactose. AB individuals add both
sugars while O individuals add neither type. When type A individuals receive type B blood,
their immune system mounts a response to reject the galactose-containing blood and vice-versa.
A) Based on this, which blood type is considered the universal donor and which is the universal
acceptor?
Universal Donor: Type O
Universal Acceptor: Type AB
B) If someone with type B blood mates with someone of type AB blood, is it theoretically
possible for this couple to have a child with type A blood? Why or why not?
Yes, this is possible. If the parent with type B blood is heterozygous (IBi) then a child with type
A blood is possible. -
Czar Nicolas II and Czarina Alexandra who ruled Russia during the Bolshevik revolution of
1917 had four girls (one being the famous Anastasia) before finally having their last and most
prized child, a boy named Alexis who was destined to succee -
Alexis had a 50% chance of inheriting hemophilia because his mother was a carrier. Because
hemophilia is X-linked, only the mother can pass it to her son. -
From a cross of two people heterozygous at two loci, what is the probability of having a child
that expresses the dominant phenotype for both loci? -
Parents: AaBb x AaBb
What is probability of child A_B_?
Probability of A_ = 3/4
Probability of B_ = 3/4
Overall probability = 3/4 * 3/4 = 9/16 -
What is the probability of getting an AaBB child from a cross of two people heterozygous at
both loci? -
Parents: AaBb x AaBb
What is probability of child AaBB?
Probability of Aa = 1/2
Probability of BB = 1/4
Overall probability = 1/2 * 1/4 = 1/8 -
The most common phenotype in a population. In Drosophila, for example,
red eyes is wild-type. - wild type
- How do genes get named?
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In Drosophila, a gene is names after the first mutant phenotype that
is discovered. - How is the wild-type allele labeled?
- The wild-type allele is labeled with a "+".
- How is the dominant allele labeled?
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The letter identifying the mutant is lowercase if the allele
is recessive (as in white eyes), or it is uppercase for those mutations that are dominant to the wild
type allele - big bang was how many years ago?
- 13.7 billion years
- first eukaryotes?
- 1 billion years ago
- fossil record how old
- 3 billion years
- exchange or recombination of genetic material
- sex
- what are the advantages of doing sexual over asexual reproduction?
- genetic variation
- what are the advantages of asexual over sexual reproduction
- saves time and energy
- when there is haploid and diploid states
- alternation of generations
- any of a series of genes that occupies the same positon on a chromosome
- allele
- any chromosome that isnt a sex chromosome
- autosome
- that which is subject to natural selection
- life
- process by which a population becomes adapted to an environment over time
- natural selection
- gives an estimate of how old something is
- absolute dating
- universe arose when matter was flung outward from the central origins
- big bang
- method of aging specimens, works for things up to 40,000 years old
- carbon 14 dating
- period that started 65 million years ago to present, divided tertiary and quaternary age of mammals
- cenozoic era
- theory that earth started with one continet, pangea, and since has broken into 7
- continental drift
- technique of absolute dating, uses rings in trees
- dendrochronology
- remains or traces of an organism that lived in the geological past
- fossil
- time scale from when earth started, about 4600 million years ago to present
- geological time scale
- chemical compound, has same molecular formula but different molecular structures or different arangements of atoms in space
- isomer
- one of two or more atoms of the same element that have the same number of protons but different number of neutrons
- isotope
- 248 million years ago to 65 million years ago, age of reptiles
- mesozoic era
- one who studies extinct organisms or their fossils
- paleontologist
- 590 million years ago to 248 million years ago
- paleozoic
- first continent
- pangea
- theory that earth surface is covered in plates which move as time goes on
- plate techtonics
- 5 billion years ago to 570 million years ago
- precambrian era
- chemical conversion of L-form amino acids to D-form amino acids after an organism dies
- racemization
- uses decay of radioactive elements to date specimens
- radio carbon dating or carbon dating
- used the most for fossil age
- radiometric dating
- dates specimens in relation to one another
- relative dating
- formed by layers of minerals that settle in water
- sedimentary rock
- continents move this far a year
- 2.5 to 15 cm
- pangaea broke into these pieces
- northern laurasia and southern gondwana
- three clues to pangaea
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1. continents fit together like puzzle pieces 2. rock formations on africa and south america are same age and structure
3. geologists have found similar scratches on rocks on SA, africa, india, australia, and antarctica - earths crust is composed of??
- silicates, mainly 02 and silicon
- what is the crust floating on?
- a very hot, nearly liquid layer of the earth called the core
- crust is seperated into sections known as
- techtonic plates
- half life is determined by the number of these given off a minute
- beta radiations
- number of possible chromosome combinations at metaphase one
- independent assortment
- this only occurs when there is a genetic variation in a population
- evolution through natural selection
- points where paired chromosomes stay in contact
- chiasmata
- group of cells arising from an ancestral cell
- clone
- union of male and female gametes
- fertilization
- parent cell divides to form two or more similar daughter cells
- fission
- reproductive cell
- gamete
- generation of a plant life cycle in which gametes are produced
- gametophyte
- made of DNA, part of a chromosome, determins a particular characteristic
- genes
- seperation of cells into alleles independent of the way other alleles have seperated
- independent assortment
- number and structure of the chromosomes in the nucleus of a cell
- karyotype
- sequence of organism from fusion of gametes in one generation to the same stage in the next
- life cycle
- position of a gene on a chromosome
- locus
- rearrangement of genes that occurs when gametes are formed
- recombination
- reproductive cell that can develop into an individual without first fusing with another reproductive cell
- spore
- generation of plants that produce spores
- sporophyte
- the result of fertilization
- zygote
- XX
- female
- XY
- male
- two parts of genetic variation
- independent assortment and recombination
- a distinctive inherited feature of an organism
- character
- traits with simple dominant/recessive expression patterns
- mendelian traits
- study of the form and structure of organisms especially their external form; physical appearance
- morphology
- male and female gametes are derived from the same individual; autogamy
- self fertilization
- male and female gametes are derived from the same individual; self fertilization
- autogamy
- particular variant for a character
- trait
- all of the offspring of that individual have the same trait as the parent when the offspring are produced by self-pollination
- true-breeding
- heritable feature for which variants exist
- character
- each trait controlled by two alleles which seperate and pass into seperate reproductive cells
- law of segregation
- pairs of factors segregate independently of each other when reproductive cells are formed
- law of independent assortment
- outcome of a probability event is unaffected by what has happened in previous trials
- independent event
- outcome of event is affected by what has happened in previous trials
- non-independent event
- a cross made to identify hidden recessive alleles in an individual of unknown genotype
- test cross
- condition that arises when both alleles in a heterozygous organism are dominant and are fully expressed in the phenotype
- codominance
- when offspring have one parental character and not the other
- complete dominance
- only classified as either-or ex. red or white
- discrete characters
- gene interaction in which one gene suppresses the effect of another gene that is at a different locus
- epistasis
- neither allele is dominant and aspect displayed results from the partial influence of both alleles
- incomplete dominance
- 3 or more alternative forms of a gene that occupy the same locus
- multiple alleles
- an allele that has more than one effect
- pleiotropy
- determination of a particular characteristic by many genes, each having a small individual effect
- polygenic inheritance
- controlled by more than one gene
- qualitative character
- more than two alleles for a trait
- multiple alleles
- both alleles are exhibited ex. blood type
- codominance
- skin color is many different shades!
- polygenic inheritance
- one gene has multiple effects
- pleiotropy
- color blindness also means a greater frequency of crossed eyes
- pleiotropy
- a gene at one locus can affect the expression of a gene at a different locus
- epistasis
- hair can be brown or blonde, but another gene codes for whether or not hair will be white or colored
- epistasis
- demonstrates a continuum of phenotypes
- polygenic inheritance
- law of segregation say alleles segregate when?
- in meiosis one
- find independent probabilities and multiply together
- rule of multiplication
- if an event can occur more than one way, find individual probablilities and add together
- rule of addition
- both alleles contribute equally to a phenotype
- codominance
- analysis of mating that has already occurred
- pedigree
- caused by a mutant allele that codes for a protein involved in chloride ion transport, leads to extreme mucous build up
- cystic fibrosis
- afflicted individuals accumulate salt in epithelial cells, cells become hypertonic, mucous around cells thickens
- cystic fibrosis
- disease is pleiotropic, can lead to lung infections, sterility in males
- cystic fibrosis
- 1/50 whites are carriers, 1/64 asians
- phenylketonuria PKU
- main symptom is mental retardation
- phenylketonuria PKU
- leads to high lebels of phenylalanine metabolites, which leads to mental retardation
- phenylketonuria PKU
- can be prevented by eating a life long low protein diet
- phenylketonuria PKU
- sufferers have anemia, pain, fever, and fatigue
- sickle cell disease
- 10 percent of blacks are carriers
- sickle cell disease
- affects the hemoglobin molecule found in red blood cells, is involved in oxygen transport
- sickle cell disease
- linked to preventing malaria, found where malaria is present
- sickle cell disease
- possibly the best example of natural selection in humans
- sickle cell disease
- causes progressive damage to the nervous system
- huntington's disease
- characterized by uncontrollable movements, dementia, and psychiatric disturbances
- huntington's disease
- caused by autosomal dominant mutation
- huntington's disease
- offspring 50 percent..does not skip generations
- huntington's disease
- not prevalent in early history, occurs in 30s-40s, life expectancy was only around 40
- huntington's disease
- when a gene codes for whether or not another gene is expressed
- epistasis