Biology

DNA and Genetics

1,095 Questions

DNA and genetics questions explore molecular biology, DNA replication, and genetic engineering techniques. These topics are essential for various competitive exams requiring a strong foundation in life sciences. Practice these questions to understand complex biological processes thoroughly.

DNA replication mechanismsGenetic engineering techniquesGene editing toolsPolymerase chain reactionDNA sequencing methods

DNA and Genetics Questions

Multiple choice

In lac operon, RNA polymerase binds to

  1. operator

  2. promoter

  3. activator

  4. structural proteins
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In lac operon, RNA polymerase binds to the promoter and carries out transcription.

Multiple choice

Repressor proteins are encoded by

  1. promoter genes

  2. operator genes

  3. regulatory genes

  4. structural genes
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Repressor proteins are encoded by regulatory genes. 

Multiple choice

An operon is a

  1. functioning unit of chromosome containing a cluster of DNA molecules under the control of a single promoter

  2. functioning unit of genomic DNA containing a cluster of genes under the control of a single promoter

  3. functioning unit of genomic DNA containing a cluster of genes under the control of a single operator

  4. functioning unit of chromosome containing a cluster of DNA molecules under the control of a single operator
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

An operon is a functioning unit of genomic DNA containing a cluster of genes under the control of a single promoter.

Multiple choice

Lac operon is an example of

  1. negative repressible operons

  2. negative inducible operons

  3. positive inducible operons

  4. positive repressible operons
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The lac operon is a negatively-controlled inducible operon, where the inducer molecule is allolactose.

Multiple choice

Which of the following statements is true?

  1. The lac repressor binds with lactose and transcription occurs when both glucose and lactose are present in the cell.

  2. When both glucose and lactose are absent, transcription occurs.

  3. In the absence of glucose, when lactose is present, it combines with the repressor, allowing RNA polymerase to carry on transcription.

  4. When glucose is present, cyclic AMP is high, CAP does not bind to the activator binding site and transcription of lactose is turned on.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This is a true statement.

Multiple choice

The lac operator is located

  1. adjacent to activator

  2. partially within the promoter

  3. within the structural genes

  4. just before terminator
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The lac operator lies partially within the promoter and interacts with a regulatory protein that controls the transcription of the operon.

Multiple choice

The activity of DNA gyrase is interrupted by

  1. puromycin

  2. streptomycin

  3. nalidixic acid

  4. chloramphenicol

  5. none of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

It inhibits the subunit of DNA gyrase and induces formation of relaxation complex analogue.

Multiple choice

Recombinant dependent mechanism for DNA repairing is

  1. SOS repair

  2. Base excision repair

  3. Post replication repair

  4. Photoreactivation repair

  5. Nucleotide excision repair
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Recombinant dependent mechanism takes place after DNA replication. Hence, it is considered post replication repair.