Biology

DNA and Genetics

985 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

Asia's first DNA bank is in

  1. Bangkok

  2. Bangalore

  3. Lucknow

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

It has been established by Dr. Saeed Ahmed, Director IQRA biotech services under Private Public Partnership with Biotech Park, Lucknow.

Multiple choice

RFLP (Restriction Fragment Length Polymorphism) is a

  1. growth promoter

  2. molecular marker

  3. growth retardent

  4. herbicide

  5. germicide
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

RFLP (Restriction Fragment Length Polymorphism) is a molecular marker technique used in genetics and DNA fingerprinting. It analyzes variations in DNA sequences after restriction enzyme digestion, helping identify genetic differences between individuals or species. The other options (growth promoter, retardent, herbicide, germicide) are agricultural/chemical substances, not genetic analysis tools.

Multiple choice

Eukaryotic DNA replication is a conserved mechanism. Which among the following statements regarding the DNA replication is false?

  1. Duplex DNA is always antiparallel.

  2. Two replicative polymerases synthesise DNA in opposite orientations.

  3. Okazaki fragments are formed on the lagging strand.

  4. The lagging strand usually contains longer stretches of single-stranded DNA.

  5. Each Okazaki fragment is preceded by an RNA dimer.
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Each Okazaki fragment is preceded by an RNA primer, which is displaced by the procession of the next Okazaki fragment during synthesis.

Multiple choice

Which of the following is the inducer of the lac operon?

  1. Isopropyl-β-D-thio-galactoside

  2. Phenyl-β-D-galactose (phenyl-Gal)

  3. ONPG

  4. Allolactose

  5. Phosphoenolpyruvic acid
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Allolactose is an isomer of lactose and is the inducer of the lac operon. Lactose is galactose-(β1->4)-glucose, whereas allolactose is galactose-(β1->6)-glucose. Lactose is converted to allolactose by β-galactosidase in an alternative reaction to the hydrolytic one.

Multiple choice

The activator proteins frequently binds with the pertinent DNA segment in ______________________.

  1. positive inducible operons

  2. positive repressible operons

  3. negative inducible operons

  4. negative repressible operons

  5. neutral repressible operons
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In positive repressible operons, the activator proteins are normally bound to the pertinent DNA segment. However, when an inhibitor is bound by the activator, it is prevented from binding the DNA. This stops activation and transcription of the system.

Multiple choice

Which among the following statements regarding the lac operon is incorrect?

  1. The lac repressor is a trimer of identical subunits.

  2. The repressor is an allosteric protein.

  3. Specific control of the lac genes depends on the availability of the substrate lactose to the bacterium.

  4. Transcription of all genes starts with the binding of the enzyme RNA polymerase.

  5. The first control mechanism is the regulatory response to lactose.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The lac repressor is a tetramer of identical subunits. Each subunit contains a helix-turn-helix (HTH) motif capable of binding to DNA. The operator site where repressor binds is a DNA sequence with inverted repeat symmetry.