Question: Hybrids in which the chromosome sets come from two distinct, though related, species are known as
Answer Options:
• A) Autopolyploids.
• B) Allopolyploids.
• C) Aneuploids.
• D) Bivalents.
Answer: B) Allopolyploids
Question: Why are organisms with an odd number of chromosome sets usually sterile?
Answer Options:
• A) Almost all gametes will be unbalanced.
• B) Chromosomes will fail to segregate independently during meiosis I.
• C) Chromosomes will fail to segregate independently during meiosis II.
• D) Because an odd number of chromosomal sets is present, meiosis will not occur at all.
Answer: A) Almost all gametes will be unbalanced.
Question: Monoploids are useful in plant breeding because
Answer Options:
• A) They can be used to select for plants with desirable recessive traits.
• B) They will not express any undesirable recessive traits.
• C) They are one step in the path to creating desirable polyploid plants.
• D) They are typically resistant to commercial herbicides.
Answer: A) They can be used to select for plants with desirable recessive traits. I will proceed with the remaining questions until completion.
Question: A bacterium is found that is resistant to the antibiotic gentamicin. The bacterium was isolated in a hospital where patients were routinely given gentamicin for a variety of infections. What was the pressure that selected for this resistant population?
Answer Options:
• A) Presence of gentamicin in the environment
• B) High mutation rate for the bacterium
• C) Growth situation for the bacterium
• D) Patients that did not receive the antibiotic
Answer: A) Presence of gentamicin in the environment
Question: What is a typical characteristic of bacterial chromosomes?
Answer Options:
• A) On average 5% of the genome encodes proteins.
• B) It has telomeres.
• C) It is linear.
• D) On average a gene occurs once in every 1000 bp.
• E) It is single-stranded DNA.
Answer: D) On average a gene occurs once in every 1000 bp.
Question: If the Tn10 transposon is used to mutagenize a bacterium for the purpose of creating a mutation in the his operon, what would be the most appropriate selection media?
Answer Options:
• A) Rich media that contains all of the amino acids supplemented with tetracycline
• B) Minimal media supplemented only with histidine
• C) Minimal media supplemented with tetracycline and histidine
• D) Minimal media supplemented with tetracycline alone
Answer: C) Minimal media supplemented with tetracycline and histidine
Question: A strain of E. coli is trp− his− lac−. Which medium would this bacterium grow on?
Answer Options:
• A) Minimal medium with lactose as the sugar, supplemented with histidine and tryptophan
• B) Minimal medium with glucose as the sugar, supplemented with histidine and tryptophan
• C) Minimal medium with glucose and lactose as the sugar
• D) Minimal medium with glucose as the sugar
Answer: B) Minimal medium with glucose as the sugar, supplemented with histidine and tryptophan
Question: The episome in an Hfr strain is inserted near the trp (tryptophan operon) locus. This Hfr strain is grown with an F− Trp− strain. From this mating, we isolate an F+ Trp+ strain that can readily impart the Trp+ phenotype to F− Trp− strains, but no other traits are ever transferred. (When the original Hfr strain is mated with F− strains, traits other than Trp+ can be transferred, although at lower frequency than Trp+.) What most likely has happened?
Answer Options:
• A) An F′ trp+ plasmid has been generated.
• B) Mutation occurred.
• C) Transduction occurred.
• D) Transformation occurred.
Answer: A) An F′ trp+ plasmid has been generated.
Question: Viruses are isolated from wild-type E. coli cells that have been infected with wild-type bacteriophage λ. These viruses are used to infect a Gal− strain of E. coli. A few bacterial colonies that can grow on galactose are obtained, while no bacteria that can grow on galactose are obtained from cells that were not infected. What has happened?
Answer Options:
• A) A λ gal+ phage was generated.
• B) Reversion mutations have occurred.
• C) The bacteria underwent conjugation with a Gal+ strain.
• D) The bacteria underwent transformation with a wild-type E. coli strain.
Answer: A) A λ gal+ phage was generated.
Question: Some plasmids can replicate in several distinct species of bacteria. Frequently these plasmids have transposons carrying several different antibiotic resistance genes. In a hospital that has an outbreak of several species of bacteria each carrying resistance to three drugs (streptomycin, gentamicin, and penicillin), what is the best way to determine whether or not this resistance is due to a single shared plasmid with all three resistance genes?
Answer Options:
• A) Demonstrate that all the resistant bacteria have a plasmid.
• B) Isolate plasmids from all resistant bacterial species and demonstrate that drug-sensitive cells from these same species become resistant to all three drugs when this plasmid is transformed. Confirm that the same plasmids are present in all species by sequencing the plasmid DNA.
• C) Sequence the genomes of the resistant species and demonstrate mutations in the same homologous genes.
• D) Isolate plasmids from one resistant species and transform a drug-sensitive strain of the other bacterial species to see if resistance occurs in the transformants.
Answer: B) Isolate plasmids from all resistant bacterial species and demonstrate that drug-sensitive cells from these same species become resistant to all three drugs when this plasmid is transformed. Confirm that the same plasmids are present in all species by sequencing the plasmid DNA.
Question: Penicillin stops bacterial cell wall formation by
Answer Options:
• A) Inhibition of a transpeptidase.
• B) Inhibiting synthesis of NAM.
• C) Inhibiting synthesis of NAG.
• D) Inhibiting transport of NAG and NAM past the permeable membrane.
Answer: A) Inhibition of a transpeptidase.
Question: What would happen if a transposon were to integrate into the replication origin of the bacterial genome?
Answer Options:
• A) The transposon would be replicated with the genome.
• B) The transposon would “jump” immediately to another location.
• C) The transposon would inactivate the replication origin, so no DNA replication would be possible.
• D) The transposon would express its genes constitutively.
Answer: C) The transposon would inactivate the replication origin, so no DNA replication would be possible. I will complete the remaining questions in this format until all are finished.