Single gene inheritance
A
A
Most of the mice in New York City demonstrate “straight” tails; however, a few mice exhibit “curly” tails. In this scenario, a “straight” tail would be considered the _________ phenotype, and a “curly” tail would be considered a __________ phenotype.
A.heterogametic; homogametic
B.polymorphism; wild-type
C.mutant; wild-type
D.wild-type; mutant
D.wild-type; mutant
7.An allele of a gene of interest is best described as
A.a closely related gene (with similar function) found at a different locus.
B.the regulatory region(s) of that gene.
C.a variation in the nucleotide sequence of the gene that may or may not result in a detectable phenotype.
D.a variation in the nucleotide sequence of the gene that is always associated with a detectable or observable phenotype (regardless of whether the allele is dominant or recessive).
C.a variation in the nucleotide sequence of the gene that may or may not result in a detectable phenotype.
4.Which of these traits or diseases are believed to result from the action of polygenes, which interact with one another to ultimately determine a phenotype?
A.human skin color
B.Atherosclerosis
C.Hypertension
D.human height
E.all of these
E.all of these
1.If DNA sequencing data indicates that two nuclear genes in a diploid eukaryote are physically linked, we can say with confidence that these two genes
A.are homologs
B.are separated by no more than 1 m.u.
C.are located on the same chromosome
D.are located on separate chromosomes
E.None of the these
C.are located on the same chromosome
2.A yeast strain harboring a temperature-sensitive allele has a wild-type phenotype at the permissive temperature and a mutant phenotype at the restrictive temperature. This is an example of
A.Codominance
B.incomplete dominance
C.environmental influence on penetrance
D.Pleiotropy
E.dominant inheritance
C.environmental influence on penetrance
3.A researcher is studying two populations of mice—one population where all mice have the genotype d/d and another population where all mice have the genotype D/d. In this scenario, the d/d mice would be considered ____________ and the D/d mice are ______________.
A.heterozygous; homozygous dominant
B.monohybrids; heterozygous
C.homozygous recessive; monohybrids
D.homozygous dominant; homozygous recessive
E.heterozygous; homozygous recessive
C.homozygous recessive; monohybrids
5.Meiosis takes place in
A.haploid cells only.
B.diploid cells only.
C.haploid or diploid cells.
D.somatic cells.
E.haploid, diploid, or somatic cells.
B.diploid cells only.
5.A researcher is performing an experiment where she takes the nucleus of a cat somatic cell and introduces it into an “enucleated” rabbit egg cell. The resulting egg cell is exposed to an electric current, which jumpstarts embryonic development. What could you predict regarding the resulting embryo?
A.The embryo would be unviable, because the structure of cat DNA and rabbit DNA are very different.
B.The resulting embryo would be fully “cat-like” in its genotype and phenotype, as only the DNA content of a cell’s nucleus determines the traits of a cell or organism.
C.The resulting embryo would be fully “rabbit-like” in its genotype and phenotype, as only the DNA content of mitochondria (in the cytoplasm) determines the traits of a cell or organism.
D.The resulting embryo would appear “cat/rabbit-like” (i.e., would resemble a hybrid organism), because genetic information is contributed both by the cat nucleus and by mitochondria in the rabbit cytoplasm.
E.None of these
D.The resulting embryo would appear “cat/rabbit-like” (i.e., would resemble a hybrid organism), because genetic information is contributed both by the cat nucleus and by mitochondria in the rabbit cytoplasm.
4.You construct a genetic linkage map by following allele combinations of three genes located on the same chromosome—X, Y, and Z. You determine that the X and Y loci are 3 cM apart, the X and Z loci are 3 cM apart, and the Y and Z loci are 6 cM apart. The distances between these loci (i.e., how many cM separate these locations) are most likely based on
A.direct DNA sequencing of the chromosomal region in question
B.recombination frequencies
C.physically measuring the distances between these loci using a microscope
D.independent assortment of these alleles
B.recombination frequencies
9.A researcher has crossed two dihybrid plants with purple-colored flowers with the genotype a+/a ; z+/z. The mutant a/a gives white flowers, while the mutant zz gives pink flowers. The progeny of this cross has the phenotypic ratio of 9 purple: 3 pink: 4 white. What type of gene interaction do these results suggest?
A.dominant epistasis
B.recessive epistasis
C.Suppression
D.the two genes do not interact in any way
E.the two genes act in the same pathway
B.recessive epistasis
4.Mitosis takes place in
A.haploid cells only.
B.diploid cells only.
C.haploid or diploid cells.
D.bacterial cells only.
C.haploid or diploid cells.
6.During meiosis I:
A.homologous chromosomes pair to form a group of four chromatids at the “equatorial plane.”
B.homologous chromosomes align individually at the “equatorial plane,” similar to what occurs during mitosis.
C.homologous chromosomes align and are held together only at their centromeres.
D.sister chromatids separate and are drawn to opposite ends of a cell.
A.homologous chromosomes pair to form a group of four chromatids at the “equatorial plane.”
7.A male Drosophila melanogaster is genotypically e+/e−, where e (ebony) is an autosomal gene. Of the four gametes produced during meiosis, how many of these gametes will likely carry both the e– allele and the Y chromosome (assuming that alleles in flies follow Mendel’s first and second laws)?
A.None
B.1/4
C.1/2
D.3/4
E.all of them
7.A male Drosophila melanogaster is genotypically e+/e−, where e (ebony) is an autosomal gene. Of the four gametes produced during meiosis, how many of these gametes will likely carry both the e– allele and the Y chromosome (assuming that alleles in flies follow Mendel’s first and second laws)?
A.None
B.1/4
C.1/2
D.3/4
E.all of them
6.If two genes are tightly linked, such that no crossing over occurs between them, then
A.all progeny resulting from a cross will have a parental genotype
B.all progeny resulting from a cross will have a “nonparental” genotype
C.all progeny resulting from a cross will be recombinants
D.50% of progeny resulting from a cross will have a parental genotype, and 50% will have a “nonparental” genotype
E.25% of progeny resulting from a cross will have a nonrecombinant genotype, and 75% will have a recombinant genotype
A.all progeny resulting from a cross will have a parental genotype
6.Complementation tests are used to determine
A.whether a new mutant phenotype is dominant or recessive to another mutant phenotype.
B.whether two phenotypically identical mutants carry mutations in the same or in different genes.
C.whether an organism with the genotype A/- is actually A/A or A/a (by crossing it with a recessive—a/a―tester organism).
D.whether an organism carries any temperature-sensitive alleles.
E.which alleles in an organism are pleiotropic.
B.whether two phenotypically identical mutants carry mutations in the same or in different genes.
9.If a gene is haploinsufficient, you would predict that
A.a null mutant allele of this gene will behave in a dominant fashion.
B.a null mutant allele of this gene will behave in a recessive fashion.
C.an organism must carry two null alleles of this gene in order to demonstrate a mutant phenotype.
D.heterozygous diploids bearing a null mutant allele and a wild-type allele of this gene will be viable and demonstrate no mutant phenotype.
E.this gene cannot encode a protein.
A.a null mutant allele of this gene will behave in a dominant fashion.
10.An individual displays a dominant phenotype. To determine whether the individual is homozygous for the dominant allele or heterozygous at that locus, it would be best to do a
A.monohybrid cross.
B.reverse genetics experiment.
C.genome sequencing analysis.
D.testcross.
E.forward genetics experiment.
D.testcross.
10.A researcher is interested in genotypes in mice. He knows the following: the probability of a mouse having the genotype d/d is 1/2, the probability of a mouse having the genotype t/t is 1/4, and the probability of a mouse having the g/g genotype is 1/8. Using this information, the researcher can determine that the probability of a mouse having the genotype d/d ; t/t ; g/g is _________.
A.1/8 (i.e., 1/2 X 1/4)
B.3/4 (i.e., 1/2 + 1/4)
C.1/16 (i.e., 1/2 X 1/8)
D.7/8 (i.e., 1/2 + 1/4 + 1/8)
E.1/64 (i.e., 1/2 X 1/4 X 1/8)
E.1/64 (i.e., 1/2 X 1/4 X 1/8)
11.To test for gene linkage a dihybrid testcross of A/a ∙ B/b x a/a ∙ b/b is carried out resulting in 100 progeny. Do these resulting phenotypes support gene linkage?
A B 30
A b 22
a B 20
a b 28
A.No, all four (4) phenotype combinations are represented in the progeny.
B.No, the phenotype proportions are less than ±0.05 from the expected proportions for independent assortment.
C.Yes, the phenotype proportions are not equal.
D.Yes, their phenotypic proportions are greater than ±0.02 from the expected proportions for independent assortment.
E.Unknown, a χ2 (chi-square) test must be calculated before inferring linkage.
E.Unknown, a χ2 (chi-square) test must be calculated before inferring linkage.
8.A researcher has crossed two dihybrid fish with the genotype d+/d ; t+/t. He notices that the progeny of this cross demonstrate a phenotypic ratio of 9:7. What type of gene interaction do these results suggest?
A.dominant epistasis
B.recessive epistasis
C.suppression
D.The two genes do not interact in any way.
E.The two genes act in the same pathway.
E.The two genes act in the same pathway.
16.Consider a nondebilitating hereditary condition in humans. If two affected parents produce an unaffected daughter, then the allele responsible for the condition must be
A.autosomal dominant.
B.autosomal recessive.
C.X-linked dominant.
D.X-linked recessive.
E.either B or D.
A.autosomal dominant.
21.A young man’s family is afflicted by red-green color blindness. He draws a pedigree of his family detailing the inheritance of this condition, and notices that—in his family—only he and his grandfather demonstrate red-green color blindness. Furthermore, none of his aunts or uncles has this condition, and his brother can distinguish between red and green. Red-green color blindness is most likely a(n)
A.X-linked dominant disorder.
B.autosomal dominant.
C.autosomal recessive.
D.X-linked recessive.
D.X-linked recessive.
12.What characteristic explains the reason many commercial crop seeds are produced annually by crossing different pure lines?
A.hybrid vigor
B.heteroplasmons
C.Heteromorphism
D.quantitative trait loci
E.cytoplasmic segregation
A.hybrid vigor
9.Which of these would be considered the first step in a crossover event?
A.a double-stranded break occurring in the DNA of a chromatid
B.the formation of heteroduplex DNA
C.the formation of Holliday junctions
D.the erosion of DNA in one chromatid
E.the “invasion” of one chromatid by another
A.a double-stranded break occurring in the DNA of a chromatid
10.Which of these examples best represents variable expressivity?
A.In a population of mice all having the genotype G/g, half of the mice have gray coats and half have white coats.
B.In a population of mice all having the genotype G/g, mice demonstrate coats ranging in color from light gray to very dark gray (almost black).
C.In a population of mice all having the genotype G/g, all mice demonstrate coats of only one color (gray).
D.In a population of mice all having the genotype G/g, all mice completely lack any pigmentation in their coats (i.e., have white coats).
B.In a population of mice all having the genotype G/g, mice demonstrate coats ranging in color from light gray to very dark gray (almost black).