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

Regarding the cancer genome sequencing, which among the following statements is incorrect?

  1. Cancer genome sequencing is the whole genome sequencing of a single, homogeneous or heterogeneous group of cancer cells.

  2. Cancer genome sequencing involves direct sequencing of primary tumor tissue.

  3. Cancer genome sequencing is not limited to WG sequencing.

  4. Cancers are homogeneous populations of cells.

  5. Cancer genome sequencing provides clinically relevant information in patients with rare tumor types.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Cancers are heterogeneous populations of cells. When sequence data is derived from a whole tumor, information about the differences in sequence and expression pattern between cells is lost. This difficulty can be ameliorated by single-cell analysis.

Multiple choice

The DNA profiling method used extensively by the scientists to identify genes whose expression is altered in response to pathogens is ______________.

  1. GeneID

  2. comparative genomic hybridization

  3. gene expression profiling

  4. fusion genes microarray

  5. genome tiling arrays
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The microarray-based gene expression profiling can be used to identify genes whose expression is changed in response to pathogens or other organisms by comparing gene expression in infected to that in uninfected cells or tissues.

Multiple choice

MacLeod and McCarthy identified the main substance of transformation in bacteria as

  1. RNA

  2. DNA

  3. Plasmid

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

MacLeod and McCarty (with Avery) identified DNA as the transforming substance in their famous 1944 experiment on bacteria. They demonstrated that purified DNA from virulent bacteria could transform non-virulent bacteria, providing strong evidence that DNA was the genetic material. This was a landmark discovery in molecular biology.

Multiple choice

Griffith effect is also known as bacterial

  1. coupling

  2. transformation

  3. effect

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

Griffith effect is also known as bacterial transformation. Transformation is the genetic alteration of a cell resulting from the direct uptake and incorporation of exogenous genetic material (exogenous DNA) from its surroundings and taken up through the cell membrane.

Multiple choice

Identify the false statement(s).

  1. In mismatch correction repair, the parental DNA strand is distinguished from the daughter strand by acetylation.
  2. The basis for blue-white screening with pUC vectors is intraallelic complementation.
  3. Nude mice refers to mice without thymus.

  1. Only 1

  2. Only 2

  3. Only 3

  4. 1 and 2

  5. 1 and 3
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In mismatch correction repair, the parental DNA strand is distinguished from the daughter strand by methylation.The mismatch repair deals with correcting mismatch of the normal bases using BER or NER enzyme systems. 

Multiple choice

Enzymes from different alleles of the same gene are called

  1. apoenzymes

  2. holoenzyme

  3. alloenzyme

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

Alloenzymes (or isozymes) are enzymes that catalyze the same reaction but are encoded by different alleles of the same gene. They may differ in kinetic properties, regulation, or tissue distribution while performing the same catalytic function.

Multiple choice

Plasmids of bacteriophages are

  1. Vectors

  2. Biological scissors

  3. Spilcers

  4. Genomes

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

Bacteriophage plasmids serve as vectors in genetic engineering, carrying foreign DNA into host cells. They are not genomes (complete genetic material), biological scissors (restriction enzymes), or splicers (DNA ligases).

Multiple choice

Directions: For this question, select the best of the answer from the choices given.

In the film, ‘Jurassic Park’, scientists create living dinosaurs by replicating dinosaur DNA found inside an insect that had bitten a dinosaur and was then trapped in amber. Although, such a feat has not yet been accomplished, one day modern science will probably succeed in recreating prehistoric creatures in a similar manner. All of the following assumptions underlie the conclusion of the passage above except that

  1. to accurately replicate DNA in a laboratory will be a possibility someday

  2. DNA of a creature provides sufficient genetic information about a creature, that it allows recreation of the animal

  3. the functioning of DNA has not yet been understood by the scientist and the probability of the same is not good for future as well

  4. to recreate an entire creature, sufficient DNA can be extracted from an insect

  5. the probability for DNA to survive for more than tens of thousands of years inside an insect’s body is more than average
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This option cannot work as an assumption as it weakens the probability of the scientist understanding the basic concept of DNA.

Multiple choice

Which of the following statements is incorrect?

  1. Restriction enzymes are used to cut DNA molecule.

  2. Restriction enzymes used in recombinant technology are Type II restriction enzymes.

  3. Restriction sites of type II enzymes are generally palindromic sequences.

  4. Type II restriction enzymes require Ca2+ as a cofactor ions for their activity.

  5. Both the statements B and D.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Type II restriction enzymes usually require Mg2+ as a cofactor ion for their activity.

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 among the following enzymes plays a vital role in plasmid recombination and in DNA repair processes in prokaryotes?

  1. DnaB helicase

  2. RecQ helicase

  3. Transmembrane ATPases

  4. ATP synthase

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

In prokaryotes, RecQ is necessary for plasmid recombination and DNA repair from UV-light, free radicals and alkylating agents. This protein can also reverse damage from replication errors. In eukaryotes, replication does not proceed normally in the absence of RecQ proteins, which also function in aging, silencing, recombination and DNA repair.

Multiple choice

Which among the following statements regarding the Okazaki fragments is incorrect?

  1. Okazaki fragments are formed on the lagging template strand during DNA replication.

  2. They are separated by ~10-nucleotide RNA primers and are unligated until RNA primers are removed.

  3. On the leading strand DNA replication proceeds continuously along the DNA molecule.

  4. DNA is synthesised from 3' to 5' end.

  5. There are two pathways that have been proposed to process Okazaki fragments.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

DNA is synthesised from 5' to 3', thus when copying the 3' to 5' strand, replication is continuous. Phosphodiester links form between the 3' to 5' and nucleotides can be added with the aid of the enzyme DNA polymerase for the continuous leading strand.