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

What is merozygote?

  1. Recombinant formed in transformation

  2. Combination of bacterial and temperate phage genome

  3. Temporary RNA-DNA diploid formed during reverse transcription

  4. Two bacteria joined by conjugation tube
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The recombinant formed in transformation with slightly more amount of DNA is known as mrerozygote or partial zygote.

Multiple choice

What is F-factor?

  1. Single-stranded RNA

  2. Double-stranded circular genomic DNA

  3. Single-stranded circular genomic DNA

  4. Double-stranded circular plasmid DNA
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

F-factor is a double-stranded plasmid DNA.

Multiple choice

In a bacterial gene, the sequence TTGACA is known as

  1. pribnow box

  2. consensus sequence

  3. conservative sequence

  4. ori site

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

TTGACA is a conserved sequence seen in 35 base pair upstream of initiation site of transcription. This is known as consensus sequence.

Multiple choice

Which of the following sequences is true for prokaryotic transcription?

  1. Separation of DNA strands, joining of RNA polymerase, release of sigma factor, longation complex formation

  2. Separation of DNA strands, release of sigma factor, joining of RNA polymerase, elongation complex formation

  3. Joining of RNA polymerase, separation of DNA strands, release of sigma factor, longation complex formation

  4. Separation of DNA strands, joining of RNA polymerase, elongation complex formation, release of sigma factor

  5. Separation of DNA strands, elongation complex formation, joining of RNA polymerase, release of sigma factor

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In prokaryotes, first DNA strands separate, then RNA polymerase adds to template DNA, then the sigma factor releases and elongation complex forms.

Multiple choice

Assertion: The normal role of restriction endonucleases in bacterial cells is to degrade the bacterial chromosome into small pieces during replication. Reason: Bacterial cells protect their own DNA from degradation by restriction endonucleases by deleting all recognition sites from the genome.

Directions: In the following question, there are two statements, Assertion (A) and Reason (R). Consider both the statements independently and mark your answer as under:

1. A and R both are correct and R is the correct explanation of A.
2. A and R both are correct and R is not the correct explanation of A.
3. A is correct and R is incorrect.
4. A is incorrect and R is correct.
5. A and R both are incorrect.

  1. A and R both are correct and R is the correct explanation of A.

  2. A and R both are correct and R is not the correct explanation of A.

  3. A is correct and R is incorrect.

  4. A is incorrect and R is correct.

  5. A and R both are incorrect.
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Correct answer. The normal role of restriction endonucleases in bacterial cells is to degrade invading phage DNA. Bacterial cells protect their own DNA from degradation by restriction endonucleases by methylating the DNA at the sites that the enzyme recognises.

Multiple choice

Random amplified polymorphic DNA is a technique for

  1. the cross linkage of antigens by antibodies

  2. revealing intra-specific variation and diversity between species

  3. selection of somaclones that are resistant to herbicides

  4. reduction or elimination of the expression of individual genes

  5. transferring geometric shapes on a mask to the surface of a silicon wafer
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Random amplified polymorphic DNA (RAPD) is a method that reveals intra-specific variation and diversity between species.

Multiple choice

Which of the following explanations about restriction endonucleases is FALSE?

  1. The enzymes are natural products of bacteria.

  2. The enzymes cut DNA at defined sequences.

  3. The enzymes cut only single-stranded DNA molecules.

  4. The enzymes are named because they restrict the growth of bacteriophage.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Restriction endonucleases cut double stranded DNA and are made by bacteria, where they cut DNA injected into the cells by bacteriophage.

Multiple choice

What happens in lac operon when glucose is present?

  1. Cyclic AMP is high, the catabolite activator protein (CAP) binds to the activator binding site and transcription of lactose is turned on.

  2. Cyclic AMP is low, CAP does not bind to the activator binding site and transcription is turned off.

  3. Cyclic AMP is low, CAP binds to the activator binding site and transcription of lactose is turned on.

  4. 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
B Correct answer
Explanation

When glucose is present, the concentration of cyclic AMP is low, CAP is unable to bind to the activator binding site and transcription cannot take place.

Multiple choice

What is the function of lac repressor?

  1. It binds to the CAP site and prevents transcription.

  2. Lac repressor binds to the CAP site and facilitates transcription.

  3. Lac repressor binds to the operator and prevents transcription.

  4. Lac repressor binds to the operator and facilitates transcription.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When lac repressor binds to the operator, transcription is blocked.