BIOD 210 Module 5 Exam - Genetics - Latest 2026/2027
BIOD 210 Module 5 Exam
Genetics
Latest Update 2026/2027 - Questions & Answers - Grade A - 100% Correct
Portage Learning - Genetics Module
110 Questions with Complete Answers and Detailed Rationales
Aligned with BIOD 210 Module 5 Objectives: Microbial, Viral, and Applied Genetics
Total Qs Format Cognitive Mix Style Mix Sections
30% Recall / 50% Application / 20% 65% Application / 35%
110 Multiple Choice (A-D) 8
Analysis Recall
Section 1: Microbial Genetics Foundations (Q1-Q15)
Bacterial Genome, Plasmids, Transformation, Conjugation, & Transduction - This section examines the bacterial
chromosome, plasmids (F factor, R plasmids, virulence plasmids), and the three mechanisms of horizontal gene transfer
(transformation, conjugation, transduction) with emphasis on antibiotic resistance spread.
Q1: Which statement BEST describes the bacterial chromosome?
A. It is a linear, double-stranded DNA molecule wrapped around histones
B. It is a circular, double-stranded DNA molecule associated with proteins but not organized around
histones, typically with a single origin of replication [CORRECT]
C. It is composed of RNA rather than DNA
D. It is always located outside the nucleoid region
Correct Answer: B
Rationale: The bacterial chromosome is a circular, double-stranded DNA molecule located in the nucleoid region,
associated with proteins but NOT organized around histones (unlike eukaryotic DNA). It typically has a single origin of
replication (oriC in E. coli). Bacterial DNA is supercoiled and organized by histone-like proteins (HU, H-NS) but lacks
the nucleosome structure of eukaryotes. Plasmids are extrachromosomal and may also be circular.
Q2: A researcher discovers a small circular DNA molecule in a bacterial cell that replicates
independently of the chromosome and carries genes for antibiotic resistance. This molecule is BEST
classified as:
A. An insertion sequence
B. A plasmid (specifically an R plasmid, carrying resistance genes) [CORRECT]
C. A transposon
D. An operon
Correct Answer: B
Rationale: A small circular DNA molecule replicating independently of the chromosome and carrying antibiotic
resistance genes is a plasmid, specifically an R (resistance) plasmid. R plasmids carry genes for antibiotic resistance (e.g.,
beta-lactamases, aminoglycoside-modifying enzymes) and can transfer between bacteria via conjugation. Insertion
sequences and transposons are mobile DNA elements that move within genomes. An operon is a cluster of co-regulated
Portage Learning - Grade A - 100% Correct - Genetics Page 1
,BIOD 210 Module 5 Exam - Genetics - Latest 2026/2027
genes, not a replicating DNA molecule.
Q3: The F (fertility) factor in E. coli is BEST described as:
A. A viral genome that confers virulence
B. A plasmid carrying genes required for conjugation, including the formation of the sex pilus and
DNA transfer machinery [CORRECT]
C. A bacterial chromosome that contains fertility genes
D. A transposon that enables insertion into host DNA
Correct Answer: B
Rationale: The F (fertility) factor is a plasmid (F plasmid) that carries genes (tra genes) required for conjugation,
including formation of the sex (F) pilus and the DNA transfer machinery. F+ cells (donors, carrying F) can transfer a copy
of the F plasmid to F- cells (recipients), converting them to F+. Hfr (high frequency recombination) cells form when the F
factor integrates into the chromosome, allowing transfer of chromosomal genes at high frequency. The F factor is NOT a
viral genome, bacterial chromosome, or transposon.
Q4: A bacterial cell takes up free DNA from its environment and incorporates it into its genome. This
mechanism of horizontal gene transfer is called:
A. Conjugation
B. Transduction
C. Transformation [CORRECT]
D. Transposition
Correct Answer: C
Rationale: Transformation is the uptake of free (naked) DNA from the environment and incorporation into the bacterial
genome. Naturally competent bacteria (e.g., Streptococcus pneumoniae, Bacillus subtilis, Haemophilus influenzae) can
take up environmental DNA. Artificial transformation can be induced in the lab using chemical treatments (CaCl2) or
electroporation. Conjugation requires cell-to-cell contact via pili; transduction uses bacteriophages as vectors.
Transposition is intragenomic movement of mobile elements.
Q5: A researcher mixes an F+ E. coli strain with an F- strain on solid agar. After several hours, the F-
strain becomes F+. This conversion is BEST explained by:
A. Transformation by environmental DNA
B. Conjugation, in which the F+ donor transfers a copy of the F plasmid to the F- recipient through a
conjugation pilus [CORRECT]
C. Transduction by a temperate bacteriophage
D. Spontaneous mutation
Correct Answer: B
Rationale: The conversion of F- to F+ after contact with F+ cells is conjugation - the F+ donor cell transfers a copy of the
F plasmid to the F- recipient through a conjugation (sex) pilus and conjugation bridge. The recipient becomes F+ and can
now act as a donor. Transformation would require naked DNA in the environment. Transduction uses phages.
Spontaneous mutation is far too slow to explain this conversion. The tra genes of the F plasmid encode the pilus and
transfer machinery.
Portage Learning - Grade A - 100% Correct - Genetics Page 2
,BIOD 210 Module 5 Exam - Genetics - Latest 2026/2027
Q6: An Hfr strain is formed by:
A. Loss of the F plasmid from an F+ cell
B. Integration of the F factor into the bacterial chromosome, allowing high-frequency transfer of
chromosomal genes to F- recipients [CORRECT]
C. Conjugation between two F+ cells
D. Transduction by a virulent phage
Correct Answer: B
Rationale: An Hfr (high frequency recombination) strain forms when the F factor integrates into the bacterial
chromosome via homologous recombination between IS elements on the F plasmid and the chromosome. Hfr cells can
transfer chromosomal genes to F- recipients at high frequency, but the F factor itself rarely transfers completely (it is at
the end of the transferred DNA, and the conjugation bridge usually breaks before then). Recipients of Hfr conjugation
usually remain F- but gain chromosomal genes. Hfr mapping was historically used to map bacterial genes.
Q7: A bacteriophage transfers bacterial DNA from one cell to another. This mechanism of horizontal
gene transfer is called:
A. Transformation
B. Conjugation
C. Transduction [CORRECT]
D. Transposition
Correct Answer: C
Rationale: Transduction is the transfer of bacterial DNA from one cell to another by a bacteriophage. There are two
types: generalized transduction (any bacterial gene can be transferred due to random packaging of host DNA during lytic
cycle, common in lytic phages like P22, P1) and specialized (restricted) transduction (only genes adjacent to the prophage
integration site transfer, due to aberrant excision of a lysogenic prophage, e.g., lambda phage transferring gal or bio
genes). Transformation requires free DNA; conjugation requires cell contact.
Q8: A temperate bacteriophage such as lambda inserts its DNA into the E. coli chromosome at a
specific site, carrying only the adjacent gal or bio genes when it excises aberrantly. This mechanism is
called:
A. Generalized transduction
B. Specialized (restricted) transduction [CORRECT]
C. Transformation
D. Conjugation
Correct Answer: B
Rationale: Specialized (restricted) transduction occurs when a temperate prophage (e.g., lambda) excises aberrantly from
its integration site, taking adjacent host genes (e.g., gal or bio in E. coli) with it. Only genes near the prophage integration
site can be transferred, unlike generalized transduction where any gene can be packaged. Lambda integrates at the lambda
attachment site (attB) between the gal and bio genes. The resulting phage is called a "specialized transducing phage" and is
often defective (cannot replicate without a helper phage).
Q9: Which of the following BEST describes "competence" in the context of bacterial transformation?
A. The ability of bacteria to conjugate
B. A physiological state in which a bacterial cell can take up free DNA from the environment, often
induced by environmental signals [CORRECT]
C. The ability of a phage to infect bacteria
D. The ability of bacteria to grow on minimal media
Correct Answer: B
Rationale: Competence is a physiological state in which a bacterial cell can take up free DNA from the environment.
Natural competence is regulated and induced by environmental signals (e.g., starvation, high cell density). In
Portage Learning - Grade A - 100% Correct - Genetics Page 3
, BIOD 210 Module 5 Exam - Genetics - Latest 2026/2027
Streptococcus pneumoniae, competence is induced by competence-stimulating peptide (CSP); in Bacillus subtilis, by
ComX and ComP/ComA two-component system. Artificial competence can be induced in the lab by CaCl2 treatment or
electroporation. Competence does NOT relate to conjugation, phage infection, or auxotrophy.
Q10: A strain of Streptococcus pneumoniae that lacks a capsule (rough colony) is transformed with
DNA from a smooth (encapsulated) strain. The rough strain now produces a capsule and is virulent.
This is a classic example of:
A. Conjugation
B. Transduction
C. Transformation (the Avery-MacLeod-McCarty experiment demonstrating DNA as the genetic
material) [CORRECT]
D. Mutation
Correct Answer: C
Rationale: This is the classic transformation experiment that, in the Avery-MacLeod-McCarty experiment (1944),
demonstrated that DNA is the transforming principle (the genetic material). Building on Griffith's 1928 work showing that
a "transforming principle" converted rough (non-virulent) S. pneumoniae to smooth (virulent), Avery, MacLeod, and
McCarty showed that DNA (not protein or RNA) was the carrier of genetic information. Transformation was the
mechanism. Conjugation and transduction were not yet known.
Q11: Antibiotic resistance genes can spread rapidly through bacterial populations. The MOST
common mechanism for spreading resistance genes between distantly related bacteria is:
A. Vertical gene transfer only
B. Horizontal gene transfer, particularly conjugation via R plasmids, and transposition of mobile
genetic elements carrying resistance genes [CORRECT]
C. Spontaneous mutation only
D. Binary fission only
Correct Answer: B
Rationale: Antibiotic resistance spreads primarily through horizontal gene transfer (HGT), particularly conjugation (R
plasmid transfer via pili and conjugation machinery) and transposition of mobile genetic elements (transposons, integrons)
carrying resistance genes. R plasmids often carry multiple resistance genes (e.g., for ampicillin, tetracycline, kanamycin)
and can transfer between distantly related bacteria. Integrons capture and spread resistance gene cassettes. Vertical gene
transfer (passing genes to offspring) and mutation are slower; HGT accelerates spread dramatically.
Q12: A researcher creates a merodiploid (partial diploid) bacterial strain by introducing a plasmid
carrying a wild-type copy of a gene whose chromosomal allele is mutated. This technique is BEST used
to study:
A. Bacterial conjugation only
B. Complementation analysis (determining whether two mutations are in the same gene) and gene
dosage effects [CORRECT]
C. Bacterial transformation efficiency
D. Lysogeny
Correct Answer: B
Rationale: Merodiploids (partial diploids) are used for complementation analysis - determining whether two mutations
are in the same gene or different genes. If the wild-type gene on the plasmid restores the mutant phenotype, the mutations
complement (different genes); if not, they are in the same gene. Merodiploids are also used to study gene dosage effects
and dominant/recessive relationships in bacteria. Benzer used this approach in rII phage complementation studies. The F'
plasmid (F factor carrying chromosomal genes) is one way to create merodiploids.
Portage Learning - Grade A - 100% Correct - Genetics Page 4
BIOD 210 Module 5 Exam
Genetics
Latest Update 2026/2027 - Questions & Answers - Grade A - 100% Correct
Portage Learning - Genetics Module
110 Questions with Complete Answers and Detailed Rationales
Aligned with BIOD 210 Module 5 Objectives: Microbial, Viral, and Applied Genetics
Total Qs Format Cognitive Mix Style Mix Sections
30% Recall / 50% Application / 20% 65% Application / 35%
110 Multiple Choice (A-D) 8
Analysis Recall
Section 1: Microbial Genetics Foundations (Q1-Q15)
Bacterial Genome, Plasmids, Transformation, Conjugation, & Transduction - This section examines the bacterial
chromosome, plasmids (F factor, R plasmids, virulence plasmids), and the three mechanisms of horizontal gene transfer
(transformation, conjugation, transduction) with emphasis on antibiotic resistance spread.
Q1: Which statement BEST describes the bacterial chromosome?
A. It is a linear, double-stranded DNA molecule wrapped around histones
B. It is a circular, double-stranded DNA molecule associated with proteins but not organized around
histones, typically with a single origin of replication [CORRECT]
C. It is composed of RNA rather than DNA
D. It is always located outside the nucleoid region
Correct Answer: B
Rationale: The bacterial chromosome is a circular, double-stranded DNA molecule located in the nucleoid region,
associated with proteins but NOT organized around histones (unlike eukaryotic DNA). It typically has a single origin of
replication (oriC in E. coli). Bacterial DNA is supercoiled and organized by histone-like proteins (HU, H-NS) but lacks
the nucleosome structure of eukaryotes. Plasmids are extrachromosomal and may also be circular.
Q2: A researcher discovers a small circular DNA molecule in a bacterial cell that replicates
independently of the chromosome and carries genes for antibiotic resistance. This molecule is BEST
classified as:
A. An insertion sequence
B. A plasmid (specifically an R plasmid, carrying resistance genes) [CORRECT]
C. A transposon
D. An operon
Correct Answer: B
Rationale: A small circular DNA molecule replicating independently of the chromosome and carrying antibiotic
resistance genes is a plasmid, specifically an R (resistance) plasmid. R plasmids carry genes for antibiotic resistance (e.g.,
beta-lactamases, aminoglycoside-modifying enzymes) and can transfer between bacteria via conjugation. Insertion
sequences and transposons are mobile DNA elements that move within genomes. An operon is a cluster of co-regulated
Portage Learning - Grade A - 100% Correct - Genetics Page 1
,BIOD 210 Module 5 Exam - Genetics - Latest 2026/2027
genes, not a replicating DNA molecule.
Q3: The F (fertility) factor in E. coli is BEST described as:
A. A viral genome that confers virulence
B. A plasmid carrying genes required for conjugation, including the formation of the sex pilus and
DNA transfer machinery [CORRECT]
C. A bacterial chromosome that contains fertility genes
D. A transposon that enables insertion into host DNA
Correct Answer: B
Rationale: The F (fertility) factor is a plasmid (F plasmid) that carries genes (tra genes) required for conjugation,
including formation of the sex (F) pilus and the DNA transfer machinery. F+ cells (donors, carrying F) can transfer a copy
of the F plasmid to F- cells (recipients), converting them to F+. Hfr (high frequency recombination) cells form when the F
factor integrates into the chromosome, allowing transfer of chromosomal genes at high frequency. The F factor is NOT a
viral genome, bacterial chromosome, or transposon.
Q4: A bacterial cell takes up free DNA from its environment and incorporates it into its genome. This
mechanism of horizontal gene transfer is called:
A. Conjugation
B. Transduction
C. Transformation [CORRECT]
D. Transposition
Correct Answer: C
Rationale: Transformation is the uptake of free (naked) DNA from the environment and incorporation into the bacterial
genome. Naturally competent bacteria (e.g., Streptococcus pneumoniae, Bacillus subtilis, Haemophilus influenzae) can
take up environmental DNA. Artificial transformation can be induced in the lab using chemical treatments (CaCl2) or
electroporation. Conjugation requires cell-to-cell contact via pili; transduction uses bacteriophages as vectors.
Transposition is intragenomic movement of mobile elements.
Q5: A researcher mixes an F+ E. coli strain with an F- strain on solid agar. After several hours, the F-
strain becomes F+. This conversion is BEST explained by:
A. Transformation by environmental DNA
B. Conjugation, in which the F+ donor transfers a copy of the F plasmid to the F- recipient through a
conjugation pilus [CORRECT]
C. Transduction by a temperate bacteriophage
D. Spontaneous mutation
Correct Answer: B
Rationale: The conversion of F- to F+ after contact with F+ cells is conjugation - the F+ donor cell transfers a copy of the
F plasmid to the F- recipient through a conjugation (sex) pilus and conjugation bridge. The recipient becomes F+ and can
now act as a donor. Transformation would require naked DNA in the environment. Transduction uses phages.
Spontaneous mutation is far too slow to explain this conversion. The tra genes of the F plasmid encode the pilus and
transfer machinery.
Portage Learning - Grade A - 100% Correct - Genetics Page 2
,BIOD 210 Module 5 Exam - Genetics - Latest 2026/2027
Q6: An Hfr strain is formed by:
A. Loss of the F plasmid from an F+ cell
B. Integration of the F factor into the bacterial chromosome, allowing high-frequency transfer of
chromosomal genes to F- recipients [CORRECT]
C. Conjugation between two F+ cells
D. Transduction by a virulent phage
Correct Answer: B
Rationale: An Hfr (high frequency recombination) strain forms when the F factor integrates into the bacterial
chromosome via homologous recombination between IS elements on the F plasmid and the chromosome. Hfr cells can
transfer chromosomal genes to F- recipients at high frequency, but the F factor itself rarely transfers completely (it is at
the end of the transferred DNA, and the conjugation bridge usually breaks before then). Recipients of Hfr conjugation
usually remain F- but gain chromosomal genes. Hfr mapping was historically used to map bacterial genes.
Q7: A bacteriophage transfers bacterial DNA from one cell to another. This mechanism of horizontal
gene transfer is called:
A. Transformation
B. Conjugation
C. Transduction [CORRECT]
D. Transposition
Correct Answer: C
Rationale: Transduction is the transfer of bacterial DNA from one cell to another by a bacteriophage. There are two
types: generalized transduction (any bacterial gene can be transferred due to random packaging of host DNA during lytic
cycle, common in lytic phages like P22, P1) and specialized (restricted) transduction (only genes adjacent to the prophage
integration site transfer, due to aberrant excision of a lysogenic prophage, e.g., lambda phage transferring gal or bio
genes). Transformation requires free DNA; conjugation requires cell contact.
Q8: A temperate bacteriophage such as lambda inserts its DNA into the E. coli chromosome at a
specific site, carrying only the adjacent gal or bio genes when it excises aberrantly. This mechanism is
called:
A. Generalized transduction
B. Specialized (restricted) transduction [CORRECT]
C. Transformation
D. Conjugation
Correct Answer: B
Rationale: Specialized (restricted) transduction occurs when a temperate prophage (e.g., lambda) excises aberrantly from
its integration site, taking adjacent host genes (e.g., gal or bio in E. coli) with it. Only genes near the prophage integration
site can be transferred, unlike generalized transduction where any gene can be packaged. Lambda integrates at the lambda
attachment site (attB) between the gal and bio genes. The resulting phage is called a "specialized transducing phage" and is
often defective (cannot replicate without a helper phage).
Q9: Which of the following BEST describes "competence" in the context of bacterial transformation?
A. The ability of bacteria to conjugate
B. A physiological state in which a bacterial cell can take up free DNA from the environment, often
induced by environmental signals [CORRECT]
C. The ability of a phage to infect bacteria
D. The ability of bacteria to grow on minimal media
Correct Answer: B
Rationale: Competence is a physiological state in which a bacterial cell can take up free DNA from the environment.
Natural competence is regulated and induced by environmental signals (e.g., starvation, high cell density). In
Portage Learning - Grade A - 100% Correct - Genetics Page 3
, BIOD 210 Module 5 Exam - Genetics - Latest 2026/2027
Streptococcus pneumoniae, competence is induced by competence-stimulating peptide (CSP); in Bacillus subtilis, by
ComX and ComP/ComA two-component system. Artificial competence can be induced in the lab by CaCl2 treatment or
electroporation. Competence does NOT relate to conjugation, phage infection, or auxotrophy.
Q10: A strain of Streptococcus pneumoniae that lacks a capsule (rough colony) is transformed with
DNA from a smooth (encapsulated) strain. The rough strain now produces a capsule and is virulent.
This is a classic example of:
A. Conjugation
B. Transduction
C. Transformation (the Avery-MacLeod-McCarty experiment demonstrating DNA as the genetic
material) [CORRECT]
D. Mutation
Correct Answer: C
Rationale: This is the classic transformation experiment that, in the Avery-MacLeod-McCarty experiment (1944),
demonstrated that DNA is the transforming principle (the genetic material). Building on Griffith's 1928 work showing that
a "transforming principle" converted rough (non-virulent) S. pneumoniae to smooth (virulent), Avery, MacLeod, and
McCarty showed that DNA (not protein or RNA) was the carrier of genetic information. Transformation was the
mechanism. Conjugation and transduction were not yet known.
Q11: Antibiotic resistance genes can spread rapidly through bacterial populations. The MOST
common mechanism for spreading resistance genes between distantly related bacteria is:
A. Vertical gene transfer only
B. Horizontal gene transfer, particularly conjugation via R plasmids, and transposition of mobile
genetic elements carrying resistance genes [CORRECT]
C. Spontaneous mutation only
D. Binary fission only
Correct Answer: B
Rationale: Antibiotic resistance spreads primarily through horizontal gene transfer (HGT), particularly conjugation (R
plasmid transfer via pili and conjugation machinery) and transposition of mobile genetic elements (transposons, integrons)
carrying resistance genes. R plasmids often carry multiple resistance genes (e.g., for ampicillin, tetracycline, kanamycin)
and can transfer between distantly related bacteria. Integrons capture and spread resistance gene cassettes. Vertical gene
transfer (passing genes to offspring) and mutation are slower; HGT accelerates spread dramatically.
Q12: A researcher creates a merodiploid (partial diploid) bacterial strain by introducing a plasmid
carrying a wild-type copy of a gene whose chromosomal allele is mutated. This technique is BEST used
to study:
A. Bacterial conjugation only
B. Complementation analysis (determining whether two mutations are in the same gene) and gene
dosage effects [CORRECT]
C. Bacterial transformation efficiency
D. Lysogeny
Correct Answer: B
Rationale: Merodiploids (partial diploids) are used for complementation analysis - determining whether two mutations
are in the same gene or different genes. If the wild-type gene on the plasmid restores the mutant phenotype, the mutations
complement (different genes); if not, they are in the same gene. Merodiploids are also used to study gene dosage effects
and dominant/recessive relationships in bacteria. Benzer used this approach in rII phage complementation studies. The F'
plasmid (F factor carrying chromosomal genes) is one way to create merodiploids.
Portage Learning - Grade A - 100% Correct - Genetics Page 4
