Which of the following would be true of a plant heterozygous for a single gene controlling flower color? (Assume complete dominance).
If crossed with another heterozygous plant, the majority of progeny will have the dominant flower color.
About half of al
If crossed with another heterozygous plant, the majority of progeny will have the dominant flower color.
There will be roughly three times as many plants with the dominant flower color as plants with the recessive flower color.
The 3:1 phenotypic ratio observed among progeny of an F1 X F1 cross requires random union of gametes.
True
False
True
The 1:2:1 genotypic ratio represents relative probabilities of gamete combinations based on the assumption that gamete union is random.
Of the methods listed below, which would be the best way to determine which of two alleles of a gene is dominant to the other?
Perform crosses between series of randomly selected pairs to see which phenotype occurs more frequently.
Observe the relevant ph
Observe the relevant phenotype in the progeny that result from a cross between individuals from two different pure-breeding lines.
All progeny will be heterozygous for the trait in question and will display the phenotype that corresponds with the dominant
In peas, the round allele is dominant over the wrinkled allele. If a plant with round peas is crossed to a plant with wrinkled peas, all of the resulting plants have round peas. What is the genotype of the parents in this cross?
RR � Rr
RR � rr
rr � rr
Rr
RR � rr
In peas, the yellow allele is dominant over the green allele. If a plant with yellow peas is crossed to a plant with green peas, the resulting plants are 50% yellow and 50% green. What is the genotype of the parents in this cross?
yy � yy
YY � yy
Yy � Yy
Yy � yy
Humans have a gene, "T," that is involved in muscle formation of the tongue. Individuals with the one allele can roll their tongues, while individuals with the other allele cannot. If both parents can roll their tongues, but their child cannot, what can b
Tongue rolling is dominant, and both parents were heterozygous (Tt).
Which of the following phenomena is a consequence of Independent Assortment?
The phenotypic ratio among phenotypes produced from an F1 X F1 dihybrid cross is 9:3:3:1.
Pure breeding plants, when mated with each other, produce completely homozygous offsprin
The phenotypic ratio among phenotypes produced from an F1 X F1 dihybrid cross is 9:3:3:1.
The 9:3:3:1 ratio requires that the four gamete classes produced occur with equal frequency. This requires independent assortment.
The 9:3:3:1 ratio exhibited in the F2 generation of a dihybrid cross is a genotypic ratio.
True
False
False
A pea plant is heterozygous for two genes; one controlling height, one controlling color. The genotype is written PpTt. Based on the Law of Independent Assortment, approximately what proportion of the pollen produced by this plant should have the genotype
1/4
There are four different possible genotypes. Independent Assortment assumes that all are equally likely. Therefore, each of the four should occur with roughly equal frequency (1/4).
What phenotypic ratio would you expect as a result of a test cross between a dihybrid organism and one that is homozygous recessive for alleles at two independent loci?
1:1:1:1
9:3:3:1
3:1
9:4:2:1
1:2:1
1:1:1:1
A couple has four children. What is the probability that they would have four boys?
1/32
1/16
1/2
1/8
1/4
1/16
p values for chi-square tests provide a quantitative measure of the probability that the results of another replicate experiment will deviate as much or more from expected results by chance. By convention, the chance hypothesis is rejected when the p valu
0.05
Which term describes the individual in a pedigree whose phenotype was first brought to the attention of a medical researcher?
Progeny
Allele
Sibship
Proband
Proband
The proband is the affected individual who is first brought to the attention of a medical researcher; usually the pedigree is constructed around this individual.
Which of the following statements about autosomal recessive traits is true?
If neither parent expresses the trait, but the offspring does, both parents must be heterozygous for the trait.
If an individual expresses the trait, none of his or her offspring
If neither parent expresses the trait, but the offspring does, both parents must be heterozygous for the trait.
For an autosomal recessive trait to be expressed, the individual must be homozygous for the recessive allele. The only way (excluding new mutat
What is the most likely mode of transmission for a trait that is not expressed in parents but is expressed by one half of the sons?
Autosomal dominant
Autosomal recessive
Rare X-linked dominant
Rare X-linked recessive
Rare X-linked recessive
This trait is X-linked, and since only half the sons are affected, it is a recessive trait and the mother must have been heterozygous.
In pedigree analysis, which of the following is a hallmark of an autosomal recessive disorder?
Two unaffected parents will not have any children with the disease.
Two affected parents may produce unaffected children.
Each individual who has the disease ha
Individuals who have the disease are commonly born to normal (unaffected) parents.
A woman expressing a dominant phenotype is heterozygous (Dd) at the locus. What is the probability that the dominant allele carried by the woman will be inherited by a grandchild?
1/2
1/4
1/8
1/16
1/4
A woman expressing a dominant phenotype is heterozygous (Dd) at the locus. What is the probability that two grandchildren of the woman who are first cousins to one another will each inherit the dominant allele?
1/2
1/4
1/8
1/16
1/16
Assuming independent assortment, what phenotypic ratio would you expect to see if an individual with the genotype RrGg is self-crossed?
9:3:3:1
3:1
1:3:2:1
1:2:1
1:3
9:3:3:1
What phenotypic ratio would you expect as a result of a test cross between a dihybrid organism and one that is homozygous recessive for alleles at two independent loci?
9:4:2:1
9:3:3:1
3:1
1:2:1
1:1:1:1
1:1:1:1
You would like to know whether the progeny of a pair of mated fruit flies are distributed among the resulting four phenotypic classes in a 1:1:1:1 ratio. You perform a chi-square test and obtain a p value of 0.04. Assuming you have done the test correctly
The differences between the observed and expected counts are too large to be attributed to chance.
It is on this basis (p< 0.05) that the decision to reject the hypothesis of a 1:1:1:1 ratio is made
The larger the number of total individual counts in a chi-square test, the higher the degrees of freedom (df).
True
False
False
df increases with increasing n (number of categories), but not necessarily with increasing number of subjects.
The expected ratio of phenotypes among the progeny of a test cross is 1:1:1:1. Out of 200 total resulting progeny, 48 occur in one of the four phenotypic classes. Given this information, which of the following must also be true?
The progeny of this cross
The value of observed - expected for this cell = -2.
With a total of 200, the expected number in each cell when the predicted ratio is 1:1:1:1 = 50. The observed number is 48.
By convention, when observed experimental results deviate from expected values to an extent that would occur by chance less than 5% of the time, the experimental results are considered to be
within normal expected range.
less than one standard deviation f
statistically significantly different from the expected outcome.
The statistical interpretation of a chi-square value is determined by identifying the
degrees of freedom.
P value.
average.
mean.
joint probability.
P value.
The P value is a quantitative expression of the probability that the results of another experiment of the same size and structure will deviate as much or more from expected results by chance. The greater the difference between observed and expected result
the greater the ?2 value and the lower the P value.