Which of the following were key reasons for Mendel's success in elucidating his genetic laws?
|A)||Mendel had a strong understanding of the chemical nature of cells and knew DNA was passed on between generations.|
|B)||Mendel carefully established true breeding lines and used them in hybridization experiments carried out over multiple generations.|
|C)||Mendel's use of peas as a model organism and his experience with plant breeding in his father's orchard.|
|D)||Mendel was able to dedicate the efforts of a large research team and arranged to have very large test plots available for growing the numbers of plants required.|
|E)||All of the above|
Which is NOT a characteristic that made peas useful as a model system for Mendel's studies?
|A)||They are diploid and produce haploid gametes.|
|B)||They have a complex phenotype with much genetic variability.|
|C)||They are relatively small and easy to grow.|
|D)||They produce edible fruit.|
|E)||None of these; all of these are useful characteristics|
How might the ability of pea plants to self fertilize be a problem for genetic experiments?
|A)||Self fertile plants tend to be weaker and require more care.|
|B)||Self fertile plants are not able to produce viable seeds due to inbreeding.|
|C)||Stamens must be removed from self fertile plants to control fertilization.|
|D)||Pistils of self fertile plants are unable to accept pollen from other plants.|
Which description of plants from a true breeding strain is correct?
|A)||They only have one allele of the gene that controls the trait of interest.|
|B)||They carry two different alleles for the gene that controls the trait of interest.|
|C)||They can only reproduce by self fertilization.|
|D)||They all have dominant alleles for the trait of interest.|
Drosophila females are capable of storing sperm and using it to fertilize eggs long after mating. How might this present a problem for a geneticist?
|A)||In order to design a specific cross, females must be prevented from mating with any other strain of males.|
|B)||This allows Drosophila females to "select" sperm from the stronger male.|
|C)||Individual offspring from these females may have more than one father.|
|D)||This should not present a problem for a geneticist; it is merely a reproductive advantage to the fly if the population size is low.|
In single factor crosses between two true breeding strains of tree frog, a scientist discovers that plain green tree frogs and tree frogs with a red 'racing stripe' always produce offspring that have red racing stripes. Why?
|A)||Stripes are dominant to plain green coloration.|
|B)||Stripes must allow the frog to hide more effectively in the leaves.|
|C)||Tree frogs with stripes are often eaten by birds.|
|D)||Tree frogs with stripes must be more common than plain green ones.|
Which of the following most accurately restates Mendel's law of segregation?
|A)||Genes are inherited in discrete units from one generation to the next.|
|B)||Genes can exist in different forms, known as alleles.|
|C)||Homologous chromosomes separate during gamete formation.|
|D)||Genes on different chromosomes are inherited independently.|
You capture several interesting insects from a population in your yard. By inbreeding, you develop true breeding strains that differ only in the shape of their wings - one strain has round wings while the other strain has oval wings. How might you demonstrate that Mendel's principles apply to your insects?
|A)||Set up a monohybrid cross and determine if your F2 results are predicted by a 3:1 ratio based on the law of segregation.|
|B)||Set up a dihybrid cross and determine if your F2 results are predicted by a 9:3:3:1 ratio based on the law of independent assortment.|
|C)||Set a test cross to demonstrate that your traits breed true.|
|D)||Set up a two point test cross to demonstrate that your genes are linked.|
You set up a monohybrid cross between true breeding round winged and true breeding oval winged insects. Your F1 offspring have round wings, and you collect the following numbers of F2: Round wings: 302; Oval wings: 86. Which of the following statements is NOT correct?
|A)||The critical value for this chi square calculation is 7.815.|
|B)||The chi square value for this calculation is 1.663.|
|C)||Mendel's rules accurately predict the outcome of this cross.|
|D)||None of these; all are correct statements.|
|E)||A and B only.|
I know that black coat color in mice is dominant to albino. Black mice get a higher price at the pet store so I am disappointed when I cross a black mouse with an albino mouse and get 6 albino and 2 black mice in the litter. I expected all black. What mistake did I make?
|A)||I assumed that black alleles were more common than white.|
|B)||I assumed that white alleles were more common than black.|
|C)||I assumed that my black mouse was true-breeding.|
|D)||I assumed that my white mouse was true-breeding.|
I do a chi square analysis of the offspring from my cross of a black mouse and albino mouse. If the black mouse was heterozygous I should have expected a 1:1 ratio, and I got 6 albino and 2 black mice. What is my chi square value?
While studying for your genetics exam, a fellow student comments that the albino coat color gene in mice must be recessive. What mistake did they make?
|A)||The gene that controls the coat color character comes in both dominant and recessive forms.|
|B)||The black coat color gene is actually dominant.|
|C)||The albino coat color gene is actually dominant.|
|D)||Coat color in mice cannot be easily described in dominant/recessive relationships.|
Which is the most correct description of a dominant trait?
|A)||The most common trait in the population.|
|B)||The trait that is seen in a heterozygous organism (hybrid).|
|C)||A trait that reappears in the F2 of a monohybrid cross.|
|D)||A trait that confers a selective advantage to the organism and thus increases its frequency of reproduction.|
If you have true breeding strains that differ only in a single character, how could you determine which trait for that character is dominant?
|A)||Create another true breeding strain for another trait for that character.|
|B)||Create a monohybrid for that character and see which trait is present.|
|C)||Create a dihybrid and observe the phenotype.|
|D)||You cannot easily determine which trait is dominant.|
You cross true breeding lizards that are either green or albino and discover that all the offspring are striped green and white. Which is the most likely result if you cross two striped lizards?
|A)||All striped offspring.|
|B)||3 striped: 1 albino|
|C)||3 green: 1 albino|
|D)||1 green: 2 striped: 1 albino|
|E)||None of the above are likely outcomes.|
If you performed a dihybrid cross and found that your results were significantly different from the 9:3:3:1 ratio, what would you suspect?
|A)||You miscounted your results.|
|B)||You had too small a sample size and need to repeat the experiment.|
|C)||You picked two genes that are linked and thus do not assort independently.|
|D)||You picked two genes that are linked and thus do not segregate during gamete formation.|
Pedigrees for human genetic traits are important because:
|A)||Humans tend to have small numbers of offspring.|
|B)||Matings between humans cannot be established by experimenters.|
|C)||Knowledge about family history can help determine probabilities for individuals.|
|D)||All of the above.|
|E)||None of the above.|
Laurie met her husband Jim at a support group for families dealing with PKU (phenylketonurea), a recessive genetic disorder. Laurie and Jim both have one sister who is affected with PKU and no other family history of the disorder. They come to you as a genetic counselor to ask what their risk is of having an affected child. What do you tell them?
|A)||They must both be heterozygotes so their risk of having an affected child is ¼.|
|B)||They might both be heterozygotes so they should get tested to see if they carry the disease allele or not.|
|C)||Since neither one of them is affected, they are not at risk of having an affected child.|
|D)||You can't give them any firm answers because you don't know their genotypes.|
Which of the following statements about a pedigree would be most definitive in determining a recessive pattern of inheritance?
|A)||Two affected individuals have three affected children.|
|B)||Two unaffected individuals have one affected and two unaffected children.|
|C)||There are four instances where at least one affected parent has an affected child.|
|D)||Two known heterozygotes have two affected and one unaffected child.|
|A)||Are useful to distinguish between competing hypotheses to explain a set of data.|
|B)||Allow determination of how well a hypothesis predicts a set of experimental results.|
|C)||Can provide a quantifiable measure of goodness of fit.|
|D)||All of these.|
|E)||B and C only.|
You identify a previously unidentified plant species and decide to study its genetics. You establish true breeding strains for leaf shape (longer than wide vs equal length and width) and flower color (white vs. yellow). When you perform a dihybrid cross with these strains, you find that your results are very different than those predicted by a 9:3:3:1 ratio. You calculate a chi square and get a p value of less than 0.0001. Which of the following statements is most accurate based on this observation?
|A)||Your plant species is not governed by Mendel's laws.|
|B)||You need to test a different hypothesis, such as close linkage of these genes.|
|C)||You must have designed your crosses wrong, so you need to throw the experiment out.|
|D)||You have discovered a new mechanism of sexual reproduction.|
Mendel had extensive training in biology and heredity prior to his groundbreaking work.
Fusion of gametes is called fertilization and this creates a diploid individual.
Cross fertilization is the typical mode of reproduction for pea plants.
The probability that two heterozygotes produce an affected and a heterozygous offspring is ¾. Keep in mind that each offspring is considered a separate event.
A chi square value lower than the critical value demonstrates that the hypothesis was correct.
Critical values for the chi square test are larger when there are more degrees of freedom because each class of data is expected to show a small amount of variation.
The p values given on the chi square chart indicate probability of that much variation occurring by random chance alone.
A high chi square value always means that our hypothesis is wrong.
A chi square value below the critical value means that our hypothesis is correct.