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

Which enzyme joins Okazaki fragments together?

  1. Helicase

  2. DNA Ligase

  3. DNA polymerase

  4. DNA primase
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

DNA Ligase is the enzyme responsible for sealing the nicks between Okazaki fragments on the lagging strand. Helicase unwinds the DNA, DNA polymerase synthesizes the new strand, and primase creates the RNA primer.

Multiple choice

What is the role of DNA Polymerase I?

  1. To replace the DNA primer with RNA nucleotides

  2. To join together the Okazaki fragments on the leading strand

  3. To join together the Okazaki fragments on the lagging strand

  4. To replace the RNA primer with DNA nucleotides
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

DNA Polymerase I is specifically responsible for removing the RNA primers used during replication and replacing them with the appropriate DNA nucleotides. DNA Polymerase III is the primary enzyme for elongation.

Multiple choice

Okazaki fragments are built on the [1] strand because this strand is built [2]

  1. [1] Leading strand [2] Continuously

  2. [1] Lagging strand [2] Discontinuously

  3. [1] Lagging strand [2] Continuously

  4. [1] Leading strand [2] Discontinuously
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The lagging strand is synthesized discontinuously in short segments called Okazaki fragments because DNA polymerase can only synthesize in the 5' to 3' direction, which is away from the replication fork.

Multiple choice

The leading strand is the strand of DNA that is replicated...

  1. Discontinuously

  2. Continuously

  3. Using Okazaki fragments

  4. Using DNA Ligase
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The leading strand is oriented in the 3' to 5' direction relative to the replication fork, allowing DNA polymerase to synthesize it continuously in the 5' to 3' direction.

Multiple choice

Which of the following best explains the role of DNA primase?

  1. Creates RNA nucleotides to add to DNA

  2. Adds an RNA primer to DNA

  3. Adds a DNA primer to DNA

  4. Creates DNA nucleotides to add to DNA
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

DNA primase is a type of RNA polymerase that synthesizes a short RNA sequence (primer) complementary to the DNA template, which provides the starting point for DNA polymerase III.

Multiple choice

What is the role of single strand binding proteins (SSB) during DNA replication?

  1. Break hydrogen bonds to allow for separation of DNA strands

  2. Allow for supercoiling of the DNA

  3. Stabilize DNA strand + prevent a double helix from reforming

  4. Join the Okazaki fragments together
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Single-strand binding proteins (SSB) bind to the separated DNA strands to prevent them from re-annealing or forming secondary structures, keeping the template accessible for replication.

Multiple choice

Which enzyme unwinds DNA and how does it do this?

  1. DNA Polymerase III by breaking hydrogen bonds

  2. Helicase by breaking hydrogen bonds

  3. DNA Polymerase III by breaking covalent bonds

  4. Helicase by breaking covalent bonds
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Helicase is the enzyme that unwinds the DNA double helix by breaking the hydrogen bonds between the complementary nitrogenous bases.

Multiple choice

What role does DNA gyrase play in DNA replication?

  1. Breaks covalent bonds between DNA nucleotides

  2. Separates nitrogenous bases by breaking hydrogen bonds

  3. Supercoils the DNA in preparation for DNA replication

  4. Relieves strain + prevents supercoiling of separated strands
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

DNA gyrase (a type of topoisomerase) relieves the torsional strain (supercoiling) that builds up ahead of the replication fork as helicase unwinds the DNA.

Multiple choice botany cell and cellular organization cell theory microscope cell and its discovery

Binding of specific proteins on regulatory DNA sequences can be studied by means of 

  1. Electron microscope

  2. Light microscope

  3. Centrifugation

  4. X-ray crystallography
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

X-ray crystallography is a technique to study the structural details of crystallizable proteins and nucleic acids. X-ray microscope developed by Kirkpatrick is useful in studying detailed structures of chemicals present in solid state, e.g., haemoglobin, insulin, DNA, RNA etc. due to diffraction of X rays by different atoms of the substance. 

Binding of specific proteins on regulatory sequences of DNA will generate specific diffraction pattern of X rays which can help to identify specific proteins binding to specific regulatory regions in DNA.

Multiple choice botany cell and cellular organization cell theory microscope cell and its discovery

Binding of specific proteins on regulatory DNA sequences can be studied by means of

  1. Electron microscope

  2. Light microscope

  3. Centrifugation

  4. X-ray crystallography
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The detailed structural views of protein-DNA interfaces have been obtained through X-ray crystallography and NMR spectroscopy.

Multiple choice

DNA controls characteristics of an organism. True or False?

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

DNA contains the genetic instructions that determine an organism's physical traits, behaviors, and biological functions. These instructions are passed down from parents to offspring during reproduction.

Multiple choice

Which is an example of a vector?

  1. Bacteria

  2. Plasmid

  3. Cell

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In genetic engineering, a vector is a DNA molecule used to transport foreign genetic material into another cell. Plasmids, which are small circular DNA molecules found in bacteria, are the most commonly used vectors.