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Biology: Exam 4 Study Guide: Genetics and Evolution (Ch. 12 -14)
Study guide for BSC2010c exam 4, cover the unit of Genetics and Evolution
Terms in this set (64)
What is the difference between a genotype and a phenotype?
The phenotype is an organism's physical appearance, and the genotype is the genetic makeup.
Write the genotype of a homozygous recessive, homozygous dominant, and heterozygous pea plant using the trait flower color (p).
Different versions of a gene are called ____________.
Why are there always two alleles present for each gene at a specific locus?
Since diploid organisms have two copies of each chromosome, they have two of
each gene. Since genes come in more than one version, an organism can have two of the same alleles of a gene, or two different alleles.
True or False. A dominant allele is always written with a capital letter, whereas the recessive allele is always written in lower-case.
True or False. In a sperm or egg, both of the two alleles on the homologous chromosomes are passed on to offspring.
When genes are present on the same chromosome, they are inherited separately/ together (circle correct choice).
When genes are present on different chromosomes, they are inherited separately/ together (circle correct choice).
The name of the process described in #7 is called?
Meiosis 1 Prophase 1 /crossing over.
The name of the process described in #8 is called?
The only way that a recessive trait is ever seen in the phenotype is if the genotype is:
homozygous dominant/ heterozygous/ homozygous recessive
What is the purpose of doing a Punnett square?
The Punnett square is a square diagram that is used to predict the genotypes of a particular
cross or breeding experiment. It is named after Reginald C. Punnett, who devised the
approach. The diagram is used by biologists to determine the probability of an offspring
having a particular genotype.
Do a monohybrid cross between a homozygous recessive pea plant and a heterozygous pea plant, using the trait for flower color (p). List the genotypes and phenotypes of the offspring (in %).
50% Heterozygous Pp = Dominant Color
50% Homozygous recessive. pp = recessive color
What do the designations P, F1, and F2 mean?
P: parental generation
F1: first generation offspring
F2: Second generation offspring
If a plant with white flowers mates with a plant with red flowers, and some of their offspring have pink flowers, then this is probably due to a kind of inheritance called________
11. True or False. Each physical or chemical characteristic that organism show is due to the action of a single gene.
What is the difference between a monohybrid and a dihybrid cross?
Monohybrid cross is the inheritance of single characters and Dihybrid cross is the inheritance of 2 different characters. Differentiate between incomplete dominance and
How would you label the 4 columns and the 4 rows on a dihybrid Punnett square when a female cat with the genotype RrDd is crossed with a male cat with the genotype RrDD? (R=curly tail, r=straight tail, D=long whiskers, d=short whiskers).
RD Rd rD rd
RD RRDD RRDd RrDd RrDd
RD RRDD RRDd RrDD RrDd
rd RrDD RrDd rrDD rrDd
rd RrDD RrDd rrDD rrDd
Explain why individuals look different than what their genes predetermine them to look like.
Children inherit their parents' physical attributes, but it is a mixture from both parents.
Define polygenic inheritance
Polygenic inheritance, also known as quantitative inheritance, refers to a single inherited phenotypic trait that is controlled by two or more different genes.
Explain why two parents who both have medium color skin are able to produce offspring with either darker or lighter skin than themselves.
Skin is a polygenic trait. Recessive traits from parents could match up to be expressed in offspring.
What is the name of the pigment that produces darker skin color?
Skin color is due primarily to the presence of a pigment called melanin, which is controlled by at least 6 genes. Both light and dark-complexioned people have melanin. However, two forms are produced--pheomelanin, which is red to yellow in color, and eumelanin, which is dark brown to black.
Define pleiotropy and give an example.
In pleiotropism, a single gene affects a number of phenotypic traits in the same organism. These pleiotropic effects often seem to be unrelated to each other.
Explain what the alleles A, B, and o (of the blood group system) code for.
Type A, Type B, Type AB, and Type O blood types.
List the possible genotypes for blood type A, B, AB and O.
Type A genotype is either AA or AO. Similarly, someone who is blood type B could have a genotype of either BB or BO. Type AB is AB, Type O is OO.
Which blood type(s) can a person with type A receive in a blood transfusion? A
person with B blood type? A person with AB blood type? A person with O blood type?
A person with Type A can receive blood from: A or O
A person with Type B can receive blood from: B or O
A person with AB blood: Universal recipient, AB, A, B, O
A person with Type O blood: Universal donor- Can only receive blood from O.
What happens to the blood cells of type A if they are transfused to a person with blood type O? Which antibodies are involved?
Type O can only receive blood from O. If a Type O patient receives Type A blood, their body is incompatible, antibodies that the patient already has in his or her blood will attack the donor red blood cells and destroy them. This could cause fever, chills, chest or back pain, bleeding, increased heart rate, shortness of breath, rapid drop in blood pressure, and/or kidney damage. This is called an acute hemolytic reaction.
Which blood type is the universal donor? Why can this blood type be given to all the other blood types in a blood transfusion?
-O, Type O has no glycoproteins and won't cause a body to make antibodies against it.
A woman with blood type AB is married to a man with blood type B. She has an affair with another man who has blood type O. She becomes pregnant and has a child with blood type B. Is it possible to tell from the child's blood type who is the father? If it is not possible, explain why. If it is possible to tell, which of the men is the father?
The wife is AB, the Husband could be BB or BO, the lover is only OO. A DNA test would be needed to know who the father is. Because baby could be BB or BO.
Draw a Punnett square to determine all the possible blood types of the children from a woman with blood type O mating with a man who has blood type AB.
A AO AO
B BO BO
What are the possible genotype(s) of individuals who actually show symptoms of a genetic disorder caused by a recessive allele?
What are the possible genotype(s) of individuals who actually show symptoms of a genetic disorder caused by a dominant allele?
Heterozygous or Homozygous Dominant
Individuals who have the heterozygous genotype for a recessive disorder are called
Decide if each of the following genetic disorders is caused by a dominant or recessive allele, and state which ones are sex-linked:
A) Hemophilia: Sex linked
B) cystic fibrosis: Autosomal recessive
C) achondroplasia: Autosomal dominant
D) Color blindness: X-linked recessive
E) Huntington disease: Autosomal Dominant
F) Neurofibromatosis: Autosomal dominant
G) sickle cell disease: Autosomal Co-Dominant
H) Duchenne muscular dystrophy: X-linked recessive
I) albinism: Autosomal recessive
J) PKU: Autosomal recessive
What is the genetic difference between a person who has sickle cell disease and one who has sickle cell trait?
The SCD person has both. When someone has sickle cell trait (SCT), it means they have
inherited one sickle cell gene and one normal gene. People with SCT have both normal red
blood cells and some sickle shaped red blood cells. Most people with SCT do not have any
symptoms of sickle cell disease. A carrier has a Trait that can pass to their offspring.
When recessive disorders are carried on a sex chromosome, they are called Sex-linked
recessive disorders. These disorders are mainly carried on the (circle: X or Y) chromosome.
In sex-linked recessive disorders, why do males always show symptoms of the disease if they inherit the recessive gene, while females only show it if their genotype is homozygous recessive?
X-linked recessive inheritance is a mode of inheritance in which a mutation in a
gene on the X chromosome causes the phenotype to be expressed in males (who are
necessarily hemizygous for the gene mutation because they have one X and one Y
chromosome) and in females who are homozygous for the gene mutation (X+X).
Affected men always inherit the sex-linked recessive alleles (such as color blindness) from their: (circle: mother or father).
Is the father of a color blind woman normal or color blind? Explain your answer.
A colorblind woman must have both XX, meaning they got the trait from both parents, so the father is color blind as well.
What is the chance that a woman who is a carrier of the cystic fibrosis gene will have children who have the disorder, if her husband has cystic fibrosis?
An individual must inherit two non-functioning CF genes, one from each parent to have CF. If both parents are carriers there is a 1 in 4 (25 percent) chance that both will pass on the nonfunctioning gene, which would result in a pregnancy affected with cystic fibrosis.
What kind of genetic process causes Down syndrome?
The most common form of Down syndrome is known as Trisomy 21, a condition where individuals have 47 chromosomes in each cell instead of 46. Trisomy 21 is caused by an error in cell division called nondisjunction. This leaves a sperm or egg cell with an extra copy of chromosome 21 before or at conception.
Describe 4 syndromes that can result due to a non-disjunction event at the sex chromosomes and list the different genotypes of individuals who have these disorders.
Evolution is change in the heritable characteristics of biological populations over successive generations.
What are fossils and what kinds of remains can become fossils?
The remains or impression of a prehistoric organism preserved in petrified form or as a mold or cast in rock. Plants, Insects, or Animals.
How does evidence from:
A) the fossil record contains strong evidence that major new groups of organisms arose from
previously existing organisms.
B) genetics natural selection and sexual selection. and
C) anatomy Evolution of similarities of different species indicate that organisms change over time.
Within rock strata, where are the youngest fossils found? Where are the oldest fossils found?
Layers of strata are deposited horizontally, or nearly horizontally, and parallel or nearly parallel to the earth's surface. principle of superposition: In an undeformed sequence, the oldest rocks are at the bottom and the youngest rocks are at the top
What is the name of Darwin's book outlining the Theory of Natural Selection?
On the Origin of Species
How did the Christian view of the origin and nature of living things differ from the evidence presented by the fossil record?
Creation scientists reject this view and choose to accept the biblical version. Living fossils are nearly identical to those found in the fossil record. Best fit the evidence involves different ecological zones being buried at different times.
What is catastrophism and who proposed it?
Catastrophism is the idea that many of Earth's crustal features formed because of past cataclysmic activity. Conrado Castro.
How was the theory proposed by Comte de Buffon similar to Darwin's theory?
Buffon proposed that the debris flung out from a comet's collision with the sun became the planets. Account for the geographical distribution of similar species around the world. For a vast age of the planet and life itself, to Darwin's own theory of evolution.
What kind of support did Charles Lyell's research contribute to evolutionary thought?
Sir Charles Lyell, 1st Baronet, FRS (14 November 1797 - 22 February 1875) was a Scottish. He was a close friend of Charles Darwin and contributed significantly to Darwin's thinking on the processes involved in evolution. Including ideas about the formation of atolls, which supported Lyell's uniformitarianism.
Summarize Darwin's Theory of Natural Selection
A species is a population of organisms that
interbreeds and has fertile offspring. Living organisms have descended with modifications from species that lived before them. More organisms are produced than can survive because of limited resources.
What is speciation and what causes it?
Causes of speciation.
In the fruit fly example, some fruit fly larvae were washed up on an island, and speciation started because populations were prevented from interbreeding by geographic isolation.
However, speciation might also happen in a population with no specific extrinsic barrier to gene flow.
How does variation in a population arise?
Genetic variation can be caused by mutation (which can create entirely new alleles in
a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).
What are adaptive traits and how are they affected by natural selection?
A genetic trait that helps an organism to maximize its reproductive success. These traits can be heritable, which affects natural selection if its advantageous.
Explain why an adaptive trait may not be adaptive as time goes on.
An adaptation is a feature produced by natural selection for its current function
What kind of organism is currently thought to be the ancestral organism to all living things?
The last universal common ancestor, Luca is believed to be the oldest common ancestor of all living things
Why is it incorrect to say that a certain organism is more evolved than another?
All organisms and species have evolved to perform well in a particular environment and niche, and none are more or less evolved than any other.
Why is it incorrect to say that an individual evolves?
MISCEPCTION: Individual organisms can evolve during a single lifespan.
CORRECTION: Evolutionary change is based on changes in the genetic makeup of populations over time. Populations, not individual organisms, evolve.
What are Hox genes and how do they support evolutionary theory?
Hox genes, a subset of homeotic genes, are a group of related genes that control the body plan of an embryo along the head-tail axis. ... The protein product of each Hoxgene is a transcription factor. Each Hox gene contains a well-conserved DNA sequence known as the homeobox.
What are homologous structures and how do they support evolutionary theory?
Homologous structures are structures that are similar in different species of common ancestry:
example: the way structures develop in embryos & the pattern in which they appeared over
evolutionary history; homologous structures support evolution because the evolutionary theory
explains the existence of homologous structures adapted to different purposes as the result of
descent with modification from a common ancestor
What are vestigial structures and how do they support evolutionary theory?
Evolutionary theory predicts that features of ancestors that no longer have a function for that species will become smaller over time until they are lost
The following human pedigree shows a family affected by sickle cell disease.
What are the genotypes of the following individuals:
I1, I2, II1, II3, II4, II5, II7, III5?
Which individuals have sickle cell trait?
SCT- Carrier. SCD- Affected. N- Normal
I1: SCD I2: Normal
II1, II3, II5, II7
N, SCT, SCD, N
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