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Molecular Biology

Bacterial Recombination Practice Questions

34 free Bacterial Recombination practice questions for the Zoology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.

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Question 1 of 34 Medium

Which bacterial process involves the direct transfer of DNA through a physical connection between two cells?

  1. A Transformation
  2. B Transduction
  3. C Conjugation
  4. D Mutation

Correct answer: Conjugation

Conjugation requires direct cell-to-cell contact, usually mediated by a sex pilus. DNA is transferred from a donor to a recipient cell through this physical connection.

Question 2 of 34 Medium

The F plasmid in Escherichia coli primarily carries genes responsible for:

  1. A Resistance to multiple classes of antibiotics
  2. B Sex pilus formation and DNA transfer
  3. C Production of secreted bacterial toxins
  4. D Formation of dormant, resistant endospores

Correct answer: Sex pilus formation and DNA transfer

The F (fertility) plasmid contains tra genes that encode proteins for pilus formation and DNA transfer during conjugation. It enables donor cells to initiate conjugation.

Question 3 of 34 Medium

In bacterial transformation, DNA uptake generally occurs from:

  1. A Actively growing living donor cells
  2. B Infecting bacteriophage particles
  3. C Free DNA present in the environment
  4. D Intact plasmids transferred by contact

Correct answer: Free DNA present in the environment

Transformation involves the uptake of naked DNA fragments released into the environment. These fragments usually originate from lysed bacterial cells.

Question 4 of 34 Medium

Which bacterium was first shown to undergo natural transformation?

  1. A Escherichia coli
  2. B Streptococcus pneumoniae
  3. C Salmonella typhi
  4. D Mycobacterium tuberculosis

Correct answer: Streptococcus pneumoniae

Griffith’s experiment demonstrated transformation in Streptococcus pneumoniae. It showed that genetic material from dead cells could alter living cells.

Question 5 of 34 Medium

Generalized transduction is mediated by:

  1. A Temperate phages acting during lysogeny
  2. B Virulent phages during the lytic cycle
  3. C Direct plasmid transfer between two cells
  4. D Movement of conjugative transposon elements

Correct answer: Virulent phages during the lytic cycle

Generalized transduction occurs when virulent phages accidentally package random fragments of host DNA during the lytic cycle. Any gene can be transferred this way.

Question 6 of 34 Medium

Specialized transduction differs from generalized transduction because it:

  1. A Transfers essentially any bacterial gene at random
  2. B Occurs exclusively during the phage lytic cycle
  3. C Transfers genes near the prophage insertion site
  4. D Does not involve bacteriophages at any stage

Correct answer: Transfers genes near the prophage insertion site

Specialized transduction occurs when a temperate phage excises incorrectly from the chromosome. Only genes adjacent to the prophage site are transferred.

Question 7 of 34 Medium

Competence in bacteria refers to the ability to:

  1. A Resist the action of many antibiotics
  2. B Undergo conjugation with donor cells
  3. C Take up extracellular DNA
  4. D Form dormant, resistant endospores

Correct answer: Take up extracellular DNA

Competence is the physiological state that allows bacteria to bind and internalize extracellular DNA. It is essential for natural transformation.

Question 8 of 34 Medium

Which structure is essential for DNA transfer during bacterial conjugation?

  1. A Rotating flagellum for cell motility
  2. B Protective outer polysaccharide capsule
  3. C Sex pilus
  4. D Rigid peptidoglycan cell wall

Correct answer: Sex pilus

The sex pilus establishes contact between donor and recipient cells. It facilitates the transfer of DNA during conjugation.

Question 9 of 34 Medium

An Hfr strain of bacteria is characterized by:

  1. A A free F plasmid floating within the cytoplasm
  2. B Complete absence of any plasmids in the whole cell
  3. C Integration of F plasmid into the chromosome
  4. D Complete inability to carry out any conjugation

Correct answer: Integration of F plasmid into the chromosome

In Hfr strains, the F plasmid is integrated into the bacterial chromosome. This allows chromosomal genes to be transferred during conjugation.

Question 10 of 34 Medium

During conjugation between an Hfr cell and an F⁻ cell, the recipient usually:

  1. A Becomes a fully donor-capable F+ cell
  2. B Receives the donor's entire chromosome intact
  3. C Receives some donor chromosomal genes
  4. D Dies from the burden of excess transferred DNA

Correct answer: Receives some donor chromosomal genes

DNA transfer usually stops before the entire chromosome and F factor are transferred. As a result, the recipient receives some donor genes but remains F⁻.

Question 11 of 34 Medium

Which enzyme is essential for integration of transforming DNA into the bacterial chromosome?

  1. A DNA ligase sealing the backbone
  2. B RNA polymerase for transcription
  3. C RecA recombinase
  4. D DNA gyrase relaxing supercoils

Correct answer: RecA recombinase

RecA mediates homologous recombination between incoming DNA and the host chromosome. This integration is required for stable transformation.

Question 12 of 34 Medium

Transduction is best defined as gene transfer mediated by:

  1. A Conjugative plasmids
  2. B Naked free DNA
  3. C Bacteriophages
  4. D Mobile transposon elements

Correct answer: Bacteriophages

In transduction, bacteriophages act as vectors carrying bacterial DNA from one cell to another. This process does not require direct cell contact.

Question 13 of 34 Medium

Which of the following is NOT a mechanism of horizontal gene transfer in bacteria?

  1. A Bacterial conjugation via pilus
  2. B Uptake by transformation
  3. C Phage-mediated transduction
  4. D Binary fission

Correct answer: Binary fission

Binary fission is a method of asexual reproduction, not gene transfer between different cells. Horizontal gene transfer includes conjugation, transformation, and transduction.

Question 14 of 34 Medium

The initial discovery of bacterial conjugation was made by:

  1. A Avery and colleagues
  2. B Hershey and Chase
  3. C Lederberg and Tatum
  4. D Griffith

Correct answer: Lederberg and Tatum

Lederberg and Tatum demonstrated conjugation in Escherichia coli. They showed genetic recombination required direct contact between cells.

Question 15 of 34 Medium

Which type of transduction can transfer only a limited set of bacterial genes?

  1. A Generalized transduction by phages
  2. B Specialized transduction
  3. C Conjugation between two cells
  4. D Transformation of naked DNA

Correct answer: Specialized transduction

Specialized transduction transfers only genes adjacent to the prophage integration site. This limitation is due to incorrect excision of temperate phage DNA.

Question 16 of 34 Medium

Plasmids that carry antibiotic resistance genes and can be transferred by conjugation are called:

  1. A F plasmids
  2. B Col plasmids
  3. C R plasmids
  4. D Virulence plasmids

Correct answer: R plasmids

R plasmids carry genes conferring resistance to antibiotics. They often possess conjugative properties, enabling their spread among bacteria.

Question 17 of 34 Medium

Which condition is necessary for successful transformation?

  1. A Presence of bacteriophages
  2. B Physical contact between cells
  3. C Competent recipient cells
  4. D Integrated F plasmid

Correct answer: Competent recipient cells

Only competent cells can take up extracellular DNA. Without competence, transformation cannot occur.

Question 18 of 34 Medium

In generalized transduction, the phage particle contains:

  1. A Only the viral genome and no host DNA
  2. B Only a fragment of plasmid DNA
  3. C Random fragments of bacterial DNA
  4. D Both viral genome and plasmid DNA together

Correct answer: Random fragments of bacterial DNA

Errors during phage assembly can lead to packaging of bacterial DNA instead of viral DNA. These phages mediate generalized transduction.

Question 19 of 34 Medium

Which recombination process contributes most directly to the rapid spread of antibiotic resistance?

  1. A Transformation
  2. B Conjugation
  3. C Specialized transduction
  4. D Mutation

Correct answer: Conjugation

Conjugation allows direct transfer of R plasmids between bacteria. This enables rapid dissemination of antibiotic resistance genes.

Question 20 of 34 Medium

If a bacterium lacks RecA protein, which process will be most directly affected?

  1. A Routine binary fission during growth
  2. B Overall cellular protein synthesis capacity
  3. C Homologous recombination after DNA transfer
  4. D Adsorption of bacteriophages onto the cell surface

Correct answer: Homologous recombination after DNA transfer

RecA is essential for homologous recombination of incoming DNA with the host genome. Without RecA, transferred DNA cannot be stably integrated.

Question 21 of 34 Medium

Which process involves direct transfer of DNA between two bacterial cells through contact?

  1. A Transformation
  2. B Transduction
  3. C Conjugation
  4. D Mutation

Correct answer: Conjugation

Conjugation involves direct transfer of DNA through a physical connection called a sex pilus. It is a major mechanism of horizontal gene transfer.

Question 22 of 34 Medium

Transformation refers to:

  1. A Transfer of DNA via bacteriophage viruses only
  2. B DNA replication within the host cell
  3. C Random mutation of bacterial genes
  4. D Uptake of naked DNA from the environment

Correct answer: Uptake of naked DNA from the environment

Transformation is the uptake of free DNA fragments from the environment by a bacterial cell. This DNA may integrate into the genome.

Question 23 of 34 Medium

Transduction is defined as gene transfer mediated by:

  1. A Plasmids
  2. B Ribosomes
  3. C Enzymes
  4. D Viruses

Correct answer: Viruses

Transduction occurs when bacteriophages transfer DNA between bacteria. It is a virus-mediated process.

Question 24 of 34 Medium

The F plasmid in bacteria carries genes responsible for:

  1. A Protein synthesis
  2. B Antibiotic resistance genes
  3. C Formation of sex pilus
  4. D Metabolism

Correct answer: Formation of sex pilus

The F plasmid contains genes required for pilus formation and DNA transfer during conjugation.

Question 25 of 34 Medium

Which enzyme is essential for integration of foreign DNA during recombination?

  1. A DNA Ligase
  2. B DNA Helicase
  3. C DNA Primase
  4. D RecA protein

Correct answer: RecA protein

RecA protein facilitates homologous recombination. It helps integrate foreign DNA into the bacterial chromosome.

Question 26 of 34 Medium

Which recombination process contributes most to the spread of antibiotic resistance?

  1. A Transformation
  2. B Transduction
  3. C Conjugation
  4. D Mutation

Correct answer: Conjugation

Conjugation spreads plasmids carrying antibiotic resistance genes rapidly among bacteria.

Question 27 of 34 Medium

Plasmids carrying antibiotic resistance genes are called:

  1. A F plasmids
  2. B Ti plasmids
  3. C Lambda plasmids
  4. D R plasmids

Correct answer: R plasmids

R plasmids carry antibiotic resistance genes and can be transferred between bacteria through conjugation.

Question 28 of 34 Medium

Generalized transduction involves:

  1. A Transfer of random bacterial DNA
  2. B Transfer of specific target genes
  3. C Transfer of RNA
  4. D No gene transfer

Correct answer: Transfer of random bacterial DNA

Generalized transduction occurs when bacteriophages accidentally package random fragments of bacterial DNA.

Question 29 of 34 Medium

Specialized transduction transfers:

  1. A Only specific genes near prophage
  2. B All bacterial chromosomal genes
  3. C Only plasmid-encoded DNA
  4. D Random RNA sequences only

Correct answer: Only specific genes near prophage

Specialized transduction transfers only genes adjacent to the prophage insertion site during excision.

Question 30 of 34 Medium

Which type of transduction is mediated by lytic phages?

  1. A Generalized transduction
  2. B Specialized transduction
  3. C Conjugation
  4. D Transformation

Correct answer: Generalized transduction

Generalized transduction is mediated by lytic phages that package random bacterial DNA during infection.

Question 31 of 34 Medium

An Hfr strain is characterized by:

  1. A Integrated F factor in chromosome
  2. B Presence of a free, unintegrated plasmid
  3. C Complete absence of any plasmid DNA
  4. D Possession of an RNA-based genome

Correct answer: Integrated F factor in chromosome

In Hfr strains, the F plasmid is integrated into the bacterial chromosome. This allows transfer of chromosomal genes.

Question 32 of 34 Medium

Which of the following is NOT a mechanism of horizontal gene transfer?

  1. A Conjugation
  2. B Transformation
  3. C Transduction
  4. D Replication

Correct answer: Replication

Replication is a process of DNA copying, not gene transfer between organisms. The others are horizontal gene transfer mechanisms.

Question 33 of 34 Medium

In bacterial transformation, DNA is usually taken up from:

  1. A Environment
  2. B Virus
  3. C Ribosome
  4. D Plasmid only

Correct answer: Environment

In transformation, bacteria take up naked DNA from their surroundings. This DNA may integrate into the genome.

Question 34 of 34 Medium

If a bacterium lacks RecA protein, which process is affected?

  1. A DNA Replication
  2. B Ribosomal Protein Synthesis
  3. C mRNA Translation
  4. D Homologous Recombination

Correct answer: Homologous Recombination

RecA is essential for homologous recombination. Without it, integration of foreign DNA is impaired.

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