,BIOD 210 Module 4 Exam | Q&A | 2026/2027 | Genetics | Portage
Learning
1. Explain how multidrug-resistant pathogens have been propagated in
health clinics.
A) Through overuse and misuse of antibiotics, creating selective pressure for
resistant mutants that spread between patients and facilities
B) Through genetic drift eliminating susceptible strains
C) Through increased mutation rates induced by antibiotics
D) Through horizontal gene transfer only
Correct Answer: Through overuse and misuse of antibiotics, creating
selective pressure for resistant mutants that spread between patients and
facilities
Rationale: Overuse and misuse of antibiotics in clinical settings allow
bacteria to be repeatedly exposed to the same drugs, so rare spontaneous
mutants with resistance survive, multiply, and spread between patients and
facilities. Poor infection-control practices further propagate these multidrug-
resistant strains.
2. Two auxotrophic bacterial strains are propagated in the laboratory, one
deficient for leucine and the other deficient for biotin. When cultured alone,
they cannot grow on minimal medium, and when combined in the same
culture media, they still cannot grow in the minimal media. Can you tell if
genetic transmission occurred in this experiment in the case of genes that
control synthesis of biotin or leucine?
A) Yes, genetic transmission occurred because the strains were mixed
together
B) No, it does not appear that genetic transmission has occurred
C) Yes, because the strains are auxotrophs
D) Cannot be determined from the information provided
,Correct Answer: No, it does not appear that genetic transmission has
occurred
Rationale: If conjugation, transformation, or transduction had transferred
functional leucine or biotin genes between strains, prototrophic recombinants
would grow on minimal medium. The continued absence of growth even
when the strains are mixed indicates no genetic exchange rescued either
auxotrophy in this experiment.
3. What is the difference between an auxotroph and a prototroph?
A) An auxotroph can grow on minimal medium; a prototroph cannot
B) A prototroph can grow on minimal medium; an auxotroph cannot
C) Both can grow on minimal medium
D) Neither can grow on minimal medium
Correct Answer: A prototroph can grow on minimal medium; an auxotroph
cannot
Rationale: Prototrophs are wild-type bacteria that can synthesize all essential
nutrients and grow on minimal medium. Auxotrophs are mutant strains that
require specific nutrients (e.g., amino acids or vitamins) to be supplied in the
medium and cannot grow on minimal medium alone.
4. Conjugation in bacteria involves:
A) Uptake of naked DNA from the environment
B) Transfer of DNA via a bacteriophage
C) Direct cell-to-cell contact via a pilus
D) Spontaneous mutation
Correct Answer: Direct cell-to-cell contact via a pilus
, Rationale: Conjugation involves direct cell-to-cell contact through a pilus,
where DNA is transferred from a donor cell (F+) to a recipient cell (F−). This
is distinct from transformation (uptake of naked DNA) and transduction
(phage-mediated transfer).
5. Transformation in bacteria involves:
A) Direct cell-to-cell contact via a pilus
B) Uptake of naked DNA from the environment
C) Transfer of DNA via a bacteriophage
D) DNA replication errors
Correct Answer: Uptake of naked DNA from the environment
Rationale: Transformation is the process by which bacteria take up naked
DNA from their environment and incorporate it into their genome. This is one
of three mechanisms of horizontal gene transfer in bacteria.
6. Transduction in bacteria involves:
A) Direct cell-to-cell contact via a pilus
B) Uptake of naked DNA from the environment
C) Transfer of DNA via a bacteriophage
D) Spontaneous mutation
Correct Answer: Transfer of DNA via a bacteriophage
Rationale: Transduction is the transfer of genetic material from one
bacterium to another through a bacteriophage (virus that infects bacteria).
The phage packages bacterial DNA and transfers it to a new host cell.
Learning
1. Explain how multidrug-resistant pathogens have been propagated in
health clinics.
A) Through overuse and misuse of antibiotics, creating selective pressure for
resistant mutants that spread between patients and facilities
B) Through genetic drift eliminating susceptible strains
C) Through increased mutation rates induced by antibiotics
D) Through horizontal gene transfer only
Correct Answer: Through overuse and misuse of antibiotics, creating
selective pressure for resistant mutants that spread between patients and
facilities
Rationale: Overuse and misuse of antibiotics in clinical settings allow
bacteria to be repeatedly exposed to the same drugs, so rare spontaneous
mutants with resistance survive, multiply, and spread between patients and
facilities. Poor infection-control practices further propagate these multidrug-
resistant strains.
2. Two auxotrophic bacterial strains are propagated in the laboratory, one
deficient for leucine and the other deficient for biotin. When cultured alone,
they cannot grow on minimal medium, and when combined in the same
culture media, they still cannot grow in the minimal media. Can you tell if
genetic transmission occurred in this experiment in the case of genes that
control synthesis of biotin or leucine?
A) Yes, genetic transmission occurred because the strains were mixed
together
B) No, it does not appear that genetic transmission has occurred
C) Yes, because the strains are auxotrophs
D) Cannot be determined from the information provided
,Correct Answer: No, it does not appear that genetic transmission has
occurred
Rationale: If conjugation, transformation, or transduction had transferred
functional leucine or biotin genes between strains, prototrophic recombinants
would grow on minimal medium. The continued absence of growth even
when the strains are mixed indicates no genetic exchange rescued either
auxotrophy in this experiment.
3. What is the difference between an auxotroph and a prototroph?
A) An auxotroph can grow on minimal medium; a prototroph cannot
B) A prototroph can grow on minimal medium; an auxotroph cannot
C) Both can grow on minimal medium
D) Neither can grow on minimal medium
Correct Answer: A prototroph can grow on minimal medium; an auxotroph
cannot
Rationale: Prototrophs are wild-type bacteria that can synthesize all essential
nutrients and grow on minimal medium. Auxotrophs are mutant strains that
require specific nutrients (e.g., amino acids or vitamins) to be supplied in the
medium and cannot grow on minimal medium alone.
4. Conjugation in bacteria involves:
A) Uptake of naked DNA from the environment
B) Transfer of DNA via a bacteriophage
C) Direct cell-to-cell contact via a pilus
D) Spontaneous mutation
Correct Answer: Direct cell-to-cell contact via a pilus
, Rationale: Conjugation involves direct cell-to-cell contact through a pilus,
where DNA is transferred from a donor cell (F+) to a recipient cell (F−). This
is distinct from transformation (uptake of naked DNA) and transduction
(phage-mediated transfer).
5. Transformation in bacteria involves:
A) Direct cell-to-cell contact via a pilus
B) Uptake of naked DNA from the environment
C) Transfer of DNA via a bacteriophage
D) DNA replication errors
Correct Answer: Uptake of naked DNA from the environment
Rationale: Transformation is the process by which bacteria take up naked
DNA from their environment and incorporate it into their genome. This is one
of three mechanisms of horizontal gene transfer in bacteria.
6. Transduction in bacteria involves:
A) Direct cell-to-cell contact via a pilus
B) Uptake of naked DNA from the environment
C) Transfer of DNA via a bacteriophage
D) Spontaneous mutation
Correct Answer: Transfer of DNA via a bacteriophage
Rationale: Transduction is the transfer of genetic material from one
bacterium to another through a bacteriophage (virus that infects bacteria).
The phage packages bacterial DNA and transfers it to a new host cell.
