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6 Microbial Genetics Online Quiz Questions

Use this free practice quiz with 20 questions to review 6 Microbial Genetics, test your knowledge, and prepare for your next test or exam.

20 questions
01
True or false
1 point

True or false: After semiconservative DNA replication, each new double-stranded DNA molecule contains one original strand and one newly synthesized strand.

  1. A

    True

  2. B

    False

02
Choose one
1 point

A bacterial cell is making an mRNA copy of a protein-coding gene. Which process is occurring?

  1. A

    Translation

  2. B

    Transcription

  3. C

    Recombination

  4. D

    Replication

03
Written response
1 point

A competent bacterium takes up free DNA from its surroundings. What horizontal gene-transfer mechanism is this?

04
Fill in the blank
1 point

In bacteria, an operon groups related genes under shared and transcribes them into one .

05
Choose one
1 point

A donor bacterium transfers DNA to a recipient through direct cell-to-cell contact. Which mechanism best explains this transfer?

  1. A

    Transformation

  2. B

    Transduction

  3. C

    Conjugation

  4. D

    Mutation

06
Choose all
1 point

Which two processes can transfer bacterial DNA without direct cell-to-cell contact between donor and recipient? Select all that apply.

  1. A

    Transformation

  2. B

    Transduction

  3. C

    Conjugation

  4. D

    Cell division

07
True or false
1 point

True or false: In bacteria, transcription and translation can occur at the same time because a nucleus does not separate DNA from ribosomes.

  1. A

    True

  2. B

    False

08
Written response
1 point

What is the term for a change in downstream codons that can result when an insertion or deletion in a protein-coding sequence is not a multiple of three nucleotides?

09
Fill in the blank
1 point

When glucose is scarce, rises and binds the , which helps RNA polymerase transcribe the lac operon.

10
Choose one
1 point

When tryptophan is plentiful, which outcome is expected for the trp operon?

  1. A

    Tryptophan binds the operator and increases transcription.

  2. B

    Tryptophan scarcity strengthens repression of the operon.

  3. C

    Tryptophan helps activate a repressor that shuts down transcription.

  4. D

    The operon is transcribed most when tryptophan is plentiful.

11
Choose all
1 point

A bacterium acquires donor DNA. Which two outcomes could allow that DNA to be maintained in the recipient? Select all that apply.

  1. A

    Donor DNA recombines into a related chromosome.

  2. B

    Any transferred DNA is automatically maintained without further change.

  3. C

    A suitable transferred plasmid replicates independently.

  4. D

    The DNA remains free and cannot replicate or integrate.

12
Choose one
1 point

Under which conditions is E. coli lac operon expression strongest?

  1. A

    Lactose absent; glucose scarce

  2. B

    Lactose present; glucose abundant

  3. C

    Lactose present; glucose scarce

  4. D

    Lactose absent; glucose abundant

13
Open ended
1 point

Explain how antibiotic exposure can increase the frequency of resistant bacteria without causing mutations to arise because the bacteria need resistance.

14
Choose one
1 point

In which direction can bacterial DNA polymerases extend a newly synthesized DNA strand?

  1. A

    3′-to-5′

  2. B

    5′-to-3′

  3. C

    In either direction, depending on the strand

  4. D

    Only from the center of the chromosome outward

15
Choose one
1 point

A newly copied bacterial DNA strand consists of short Okazaki fragments. Which enzyme joins these fragments into a continuous strand?

  1. A

    Helicase joins the fragments to make a continuous strand.

  2. B

    Primase joins the fragments after removing their RNA primers.

  3. C

    DNA ligase joins the Okazaki fragments.

  4. D

    Topoisomerase joins the fragments while opening the DNA.

16
True or false
1 point

Bacterial DNA polymerases extend newly synthesized DNA strands in the 3′-to-5′ direction.

  1. A

    True

  2. B

    False

17
Choose one
1 point

A bacterium needs to coordinate expression of several genes whose products contribute to the same process. What advantage does organizing those genes in an operon provide?

  1. A

    They can be transcribed together into one mRNA under shared regulatory control.

  2. B

    Each gene must be copied into a separate mRNA by a different ribosome.

  3. C

    They are joined into one protein before transcription begins.

  4. D

    Their shared regulatory DNA prevents the genes from being transcribed.

18
Written response
1 point

What is the name of the mechanism in which a bacteriophage carries bacterial DNA from one cell to another?

19
Choose one
1 point

Which mutation in a protein-coding sequence is expected to cause a frameshift?

  1. A

    A substitution of one nucleotide always shifts the reading frame.

  2. B

    An insertion of three nucleotides shifts the reading frame.

  3. C

    A deletion of six nucleotides shifts the reading frame.

  4. D

    An insertion of two nucleotides shifts the reading frame.

20
Written response
1 point

In a bacterial population exposed to an antibiotic, resistant variants survive better than susceptible cells and become more frequent. What evolutionary process explains this increase?