At the end of ___ and cytokinesis there are 4 haploid cells
During ___ a spindle forms in a haploid cell
The centrosome duplicates and the chromosomes are not condensed
In the laboratory fruid fly, n is 4. How many different chromosome sets can be produced by one fly, excluding crossing over?
Among each chromosome pair
2^n unique combinations exist
Once it is established in a population, a new mutation
may increase or decrease in frequency depending on the environment
You are infected with an antibiotic-resistent strain of Klebsiella pnuemoniae. Where did you most likely contract it?
Current research indicates that medians
Are not similar to islands when comparing the diversity of animals or plants
Natural selection ultimately depends on favorable what?
You discover that a company illegal dumped old vats of PCBs into a nearby river. What do you expect to see?
Fish with deformities
In a monastery
Black eyes are dominant to orange eyes, and green skin is dominant to white skin. Sam, a MendAlien with black eyes and green skin, has a parent with orange eyes and white skin. Carole is a MendAlien with orange eyes and white skin. If Sam and Carole were to mate, the predicted phenotypic ratio of their offspring would be _____.
1 black eyes, green skin : 1 orange eyes, green skin : 1 orange eyes, green skin : 1 orange eyes, white skin
In order to determine the genotype of a MendAlien with black eyes and green skin, you would cross this individual with a(n) ___
A cross between two individuals with black eyes and green skin which results in an individual with orange eyes and white skin is an example of
a dihybrid cross
A phenotypic ratio of 9:3:3:1 in the offspring of a cross indicates that
Both parents are heterozygous for both genes
Mendel's laws of segregation of independent assortment
An individual heterozygous for eye color, skin color, and number of eyes mates with an individual who is homozygous recessive for all three characters; what would be the expected phenotypic ratio of their offspring? [Hint: B = black eyes, b = orange eyes; G = green skin, g = white skin; C = two eyes, c = one eye]
1 black eyes, green skin, two eyes : 1 black eyes, green skin, one eye : 1 black eyes, white skin, two eyes : 1 black eyes, white skin, one eye : 1 orange eyes, green skin, two eyes : 1 orange eyes, green skin, one eye : 1 orange eyes, white skin, two eyes : 1 orange eyes, white skin, one eye
A BbGg x bbgg cross yields a phenotypic ratio of approximately 5 black eyes, green skin : 5 orange eyes, white skin : 1 black eyes, white skin : 1 orange eyes, green skin. Which of the following best explains these results?
Mendel's law of independent assortment is being violated.
In a situation in which genes assort independently, what is the ratio of the gametes produced by an AaBBindividual?
1 AB : 1 aB
How do mutations affect an organism?
-They may cause the development of a disease-causing allele
-They may cause the development of a more beneficial allele
-They, in some cases, may have no noticeable affect
DNA replication occurs at an unbelievably fast rate. Once replication is complete, we can expect to find a ___ number of mistakes.
A female that is planning to become pregnant is concerned about her exposure to environmental mutagens which may have caused DNA mutations. In order for these mutations to become heritable, they must affect the
Her egg cells
What would indicate a base pairing mutation in DNA?
a G paired with a T
In people, a dimpled chin is an autosomal dominant trait. Many famous celebrities, such as John Travolta and Michael and Kirk Douglas, have this condition. Assume that the wrestler and actor Hulk Hogan is homozygous for the dimpled chin, and he married a woman with a round chin. They had two children, Brooke and Nick.
What proportion of their female progeny (such as Brooke Hogan) will show the trait?
What is the ratio of phenotypes in the offspring produced by the cross Aa x Aa? Assume complete dominance for the trait.
75% dominant : 25% recessive
In crossing a homozygous recessive with a heterozygote, what is the chance of getting a homozygous recessive phenotype in the F1 generation?
During which phase of the cell cycle does the Law of Segregation of Alleles occur?
Homologues separate during
What is an exception to the law of independent assortment?
When genes are linked, a few of the recombinant genotypes still occur in the offspring because of
Two healthy parents give birth to a child with cystic fibrosis, a recessive disorder. What can we say about both parents?
Both parents are heterozygous for the disease allele.
Traits controlled by sex-linked recessive genes are expressed more often in males because
The male has only one gene for the trait.
A color-blind boy has a mother with normal vision and a color-blind father. From which parent did he get the color-blind gene?
Why do males suffer from sex-linked disorders more often than females?
Males can express single recessive alleles from their single X chromosome.
A female would require ... in order to express the recessive allele.
Two recessive alleles for any gene.
Why can't a color-blind father pass this condition on to his sons?
The father only gives his Y chromosome to his sons
The gene for color vision is contained
On the X chromosome.
Codominance occurs when
Both of the alleles in a heterozygote are expressed phenotypically in an individual.
When discarding bad genes, what does the Y chromosome recombine with?
What holds a pair of copied chromosomes together?
A person with Turner's syndrome has which of the following?
A single X chromosome.
Where is the male-determining gene on the Y chromosome?
Close to the end of the left arm.
A Mendelian test cross is used to determine whether
An individual is homozygous and heterozygous
When Mendel used true-breeding white flowers and true-breeding purple flowers as the parental generation, what were the results? (Purple flower is dominant over white)
All the offspring had purple flowers.
If two parents are carriers of albinism (an autosomal recessive trait), what is the chance that their fourth child will have a homozygous genotype?
During which phase of the cell cycle does the law of independent assortment occur?
During anaphase II,
the chromosomes that separate are sister chromatids and often identical.
In pea plants, tall plants are dominant over short, and green pods are dominant over yellow. If you crossed true-breeding tall, green-podded plants with true-breeding short, yellow-podded plants, and then crossed the F1 individuals among themselves, what proportion of the F2 offspring would you expect to be tall and yellow-podded?
All of the following combinations are possible in the gametes of an organism that is AaBb except:
What would be true if linkage of two genes was complete?
Crossing over between the two genes would never occur.
A human sperm cell possesses autosomes and
Either an X or a Y chromosome.
Hemophilia is a sex-linked recessive gene that causes a blood disorder. What are the chances that the daughter of a normal man and a heterozygous woman will have hemophilia.
What are the possible genotypes of a person with type O blood?
Which of the following tools is never necessary when evaluating a gene with incomplete dominant inheritance?
A test cross is specifically used to
Determine if an individual with the dominant phenotype is a homozygote or a heterozygote.
Autosomal nondisjunction can result in
It has been discovered that some men are missing copies of a gene that converts testosterone into a form that dissolves in what?
The gene that some men are missing adds which of the following chemicals to testosterone?
Where does the testosterone used in doping usually come from?
Which ethnic group had the highest percentage of men missing copies of the gene in question?
The evolution of populations due to chance is
If color is an inherited trait in beetles, and birds are more likely to eat brown beetles than green beetles.
The frequency of the green allele will increase
In a population with brown and green alleles for color, genetic drift
has more effect on the evolution of a small population
Gene flow occurs when
Individuals move into or out of a population, changing the allele frequencies in the population.
Remember that color is an inherited trait in beetles. Which of the following is an example of natural selection?
Green beetles leave more offspring than brown beetles because they are better at finding food.
Natural selection occurs when
Organisms with one inherited trait survive and reproduce more than organisms with other traits.
Pesticide is applied to a population of insects
Some insects have a gene that makes them resistant to the pesticide. These insects survive. Insects without the gene die.
Change in population
The surviving insects reproduce. The frequency of resistant insects in the population increases.
Consider a population of bacteria that came from a single ancestor. Because bacteria reproduce asexually, there should be no variation in this population, but that violates the first postulate of natural selection. How is it then that this population of bacteria can still evolve?
Mutations must occur to create new variety in the population.
Mutation is the ultimate source of
New variety on which natural selection can act.
Both Lamarck and Darwin proposed mechanisms to explain how evolution occurs. What was different about these mechanisms?
Lamarck focused on genetic changes in an individual. Darwin focused on genetic changes in a population.
Natural selection can act on a certain trait only if the trait is
Fish in a local lake have a mixture of brown and green scales and are found throughout the lake. Over a five-year period, the lake develops more plant growth and an exotic predatory frog is introduced. What change would you expect to see in the original fish population?
The fish with green scales will be more common.
Which of the following is true about natural selection?
Natural selection acts on individuals.
Even though evolution occurs at the level of population,
Natural selection as a cause of evolution acts on individuals to bring about this change in the population.
Why is natural selection based entirely on reproductive success?
If more offspring carrying an allele are created, the frequency of the allele increases.
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