Question: Which event could result in an inversion?
Answer Options:
• A) A 360° rotation of a chromosomal region following two double-strand breaks in a chromosome’s DNA.
• B) A crossover between two DNA sequences in different places on the same chromosome and that are inverted repeats of each other.
• C) A crossover between two repeated DNA sequences that are in different places on the same chromosome and are oriented in the same direction.
• D) A crossover between two repetitive sequences on different chromosomes.
Answer: A) A 360° rotation of a chromosomal region following two double-strand breaks in a chromosome’s DNA.
Question: Inversions may be difficult to detect because they
Answer Options:
• A) Never visibly change chromosome banding patterns.
• B) Increase recombination in heterozygotes.
• C) Do not always cause an abnormal phenotype.
• D) Normally are removed immediately in natural populations.
Answer: C) Do not always cause an abnormal phenotype.
Question: Robertsonian translocations result from which of the following?
Answer Options:
• A) Breaks occur at or near the centromeres of two acrocentric chromosomes followed by the reciprocal exchange of broken parts.
• B) Two homologous chromosomes break and exchange parts.
• C) Unequal crossing-over occurs during meiosis.
• D) Two small chromosomes fuse end-to-end resulting in one chromosome with two centromeres.
Answer: A) Breaks occur at or near the centromeres of two acrocentric chromosomes followed by the reciprocal exchange of broken parts.
Question: Which of the following chromosomal rearrangements usually results in normal meiosis?
Answer Options:
• A) Translocation heterozygote
• B) Translocation homozygote
• C) Paracentric inversion heterozygote
• D) Pericentric inversion heterozygote
Answer: B) Translocation homozygote
Question: Which segregation pattern in a translocation heterozygote is likely to result in a normal zygote after fertilization?
Answer Options:
• A) Alternate
• B) Adjacent-1
• C) Adjacent-2
• D) Nondisjunction
Answer: A) Alternate I will continue listing the rest of the questions in this style.
Question: An individual with which type of chromosomal rearrangement is expected to have the lowest fertility?
Answer Options:
• A) Chromosomal duplication
• B) Pericentric inversion
• C) Translocation heterozygote
• D) Translocation homozygote
• E) Paracentric inversion
Answer: C) Translocation heterozygote
Question: What is true in translocation heterozygotes?
Answer Options:
• A) Genes that are normally located on different homologs appear to be linked.
• B) Fertility is reduced because crossing-over prevents the production of balanced gametes.
• C) The translocation chromosome is used as a Balancer because it cannot cross over with a normal chromosome.
• D) Crossing-over between normal and translocation chromosomes results in an inversion.
Answer: B) Fertility is reduced because crossing-over prevents the production of balanced gametes.
Question: Which is a characteristic of retrotransposons, but not of DNA transposons?
Answer Options:
• A) Include a gene that encodes reverse transcriptase
• B) May be present in a genome from one to millions of times
• C) Found only in humans
• D) May not have a function in their host
• E) Have short DNA sequences that are inverted repeats of each other on the ends
Answer: A) Include a gene that encodes reverse transcriptase
Question: One similarity between DNA transposons and retrotransposons is that
Answer Options:
• A) During transposition, both go through an RNA form that is copied back into DNA.
• B) Both can encode an enzyme required for mobilization.
• C) Transposition results in movement of the original transposon to a different place in the genome.
• D) They both have poly-A segments at one end.
Answer: B) Both can encode an enzyme required for mobilization.
Question: What might be the outcome of repeated duplications of one or a few genes in a species’ genome?
Answer Options:
• A) Tetraploidy
• B) Semisterility
• C) The presence of gene families
• D) Repetitive DNA that is of no use to the cell
• E) Fusion of segments of two chromosomes into one
Answer: C) The presence of gene families
Question: Which is a mechanism by which chromosomal rearrangements result in proteins with altered amino acid sequences?
Answer Options:
• A) Chromosome sets from two different species are combined in one individual.
• B) Translocations may fuse two different open reading frames.
• C) Deletions may remove regulatory regions of genes.
• D) Inversions may move a gene from euchromatin to heterochromatin.
Answer: B) Translocations may fuse two different open reading frames.
Question: Deletions are most useful for gene mapping
Answer Options:
• A) When you have a mutant allele of a gene that is recessive to normal alleles and amorphic.
• B) When you have a mutant allele of a gene that is dominant to wild-type alleles.
• C) If you have a mutant allele of a gene that results in no detectable mutant phenotype when homozygous.
• D) If you have a gain-of-function mutant allele of a gene.
Answer: A) When you have a mutant allele of a gene that is recessive to normal alleles and amorphic.