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

Match List I with List II and select the correct answer using the codes given below the Lists: List I List II (a) One gene and one enzyme theory 1. Watson and Crick (b) Coupling and Repulsion hypothesis 2. Beadle and Tatum (c) Tramsduction in bacteria 3. Bateson and Punnet (d) Semi-conservative method of DNA replication 4. Lederberg and Zinder 5. Morgan Codes:

  1. (a) 2 (b) 3 (c) 4 (d) 1

  2. (a) 2 (b) 1 (c) 4 (d) 5

  3. (a) 4 (b) 2 (c) 3 (d) 5

  4. (a) 5 (b) 3 (c) 2 (d) 1
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

One gene-one enzyme theory was proposed by Beadle and Tatum. Coupling and Repulsion phenomenon in genetics was explained by Bateson and Punnett. Transduction in bacteria was discovered by Lederberg and Zinder. The semi-conservative method of DNA replication was demonstrated by Watson and Crick (with Meselson and Stahl's experimental verification). Option A correctly matches these.

Multiple choice

Lysozyme is an enzyme used to break down bacterial cell walls to improve protein or nucleic acid extraction efficiency.The ammonium salt having positive effect on the refolding of denaturated lysozyme is

  1. calcium ammonium nitrate

  2. ceric ammonium nitrate

  3. diammonium phosphate

  4. ethylammonium nitrate
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Ethylammonium nitrate or ethylamine nitrate(EAN) is a salt with formula C2H8N2O3 or(C2H5)NH3+·NO3−. It is an odourless and colourless to slightly yellowish liquid. It is used as an electrically conductive solvent in electrochemistry and as a protein crystallization agent. It has a positive effect on the refolding of denaturated lysozyme, with the refolding yield of about 90%.

Multiple choice

Pol refers to a gene in retroviruses. The pol gene does NOT encode for

  1. RNA polymerase

  2. integrase

  3. reverse transcriptase

  4. proteases

  5. trimer
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This enzyme is involved in the production of RNA from DNA through transcription. It adds ribonucleotides to growing RNA transcripts at the 3’ end. The pol gene does not encode for NA polymerase.

Multiple choice

Which among the following statements does NOT characterise telomerase reverse transcriptase enzyme?

  1. The hTERT gene has become a main focus for gene therapy involving cancer.

  2. Plasmid DNA sequences can be manufactured using the hTERT promoter.

  3. hTERT immortalises various normal cells in culture.

  4. The hTERT gene, located on chromosome 5, consists of 16 exons and 15 introns spanning 35 kb.

  5. Telomere deficiency is associated with cancers and tumor formation.
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Telomere deficiency is often linked to aging, cancers and the conditions dyskeratosis congenita (DKC) and Cri du chat. Meanwhile, over-expression of hTERT is often associated with cancers and tumor formation.

Multiple choice

The protein coded by a tumor suppressor gene in humans is

  1. a protein which controls progression through the cell cycle

  2. a protein which helps prevent apoptosis

  3. a protein which codes for a DNA repair enzyme

  4. a protein which forms fractions of a growth factor signalling pathway

  5. a protein which acts by opposing the action of PI3K
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Tumour suppressor genes code for proteins which normally control progression through a cell cycle checkpoint. These genes only contribute to a cancer when both copies are mutated in a way which produces an inactive protein product. A single mutation inactivating one gene only has no effect. They contribute to cancer because the absence of the protein product removes controls on cell division.

Multiple choice

A division of the circular single stranded viruses has been proposed for easy and convenient study. Which among the following types of genomes is characterised by small circular DNA genome?

  1. Type I genomes

  2. Type II genomes

  3. Type III genomes

  4. Type IV genomes

  5. Type V genomes
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Type I genomes are characterized by a small circular DNA genome (approximately 2-kb), with the Rep protein and the major open reading frame (ORF) in opposite orientations. This type is characteristic of the circoviruses, geminiviruses and nanoviruses.

Multiple choice

Pfu polymerase is better than Taq polymerase because

  1. it has more efficient polymerse activity

  2. it has proof reading activity

  3. both 1 and 2

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Pfu polymerase has proof reading activity, so if there is any mispaired binding, it will repair this base pairing so that there will be no mispairing. Proof reading activity is absent in Taq polymerase, so it cannot repair any mispairing.