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

Assertion (A): Some mycoplasmas (PPLO’S) are named as L-forms. Reason (R): L-forms can be obtained by treating the bacterial cultures with enzymes like lysozyme or an antibiotic such as penicillin.

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

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

  1. 1

  2. 2

  3. 3

  4. 4

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

Correct answer:

Both (A) and (R) is correct but (R) is not the correct expalanation of (A).

Some mycoplasmas (PPLO’S) are named as L-forms where ‘L’ stands for Lister Institute. L-forms can be obtained by treating the bacterial cultures with enzymes like lysozyme or an antibiotic such as penicillin. They lyse the cell walls, due to which small spherical bodies resembling mycoplasmas (PPLO'S) are formed.

Multiple choice

ClustalW is used for

  1. structure prediction

  2. motif analysis

  3. multiple sequence alignment

  4. all of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

ClustalW is a widely used program for multiple sequence alignment. It aligns multiple DNA or protein sequences to identify conserved regions. It does not directly predict structures or perform motif analysis - those are separate bioinformatics tasks.

Multiple choice

Which of the following servers predicts the presence and location of signal peptide cleavage sites?

  1. Sigpred

  2. SignalI

  3. SignalP

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

SignalP is a widely used server that predicts signal peptide cleavage sites in protein sequences. Signal peptides are N-terminal sequences that target proteins for secretion. The other options (Sigpred, SignalI, Sigprepred) are not standard or well-known bioinformatics tools for this purpose.

Multiple choice

The mathematical representation of conserved region is known as

  1. motif

  2. profile

  3. pattern

  4. module
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A motif is a mathematically represented conserved region or pattern in biological sequences (proteins or DNA) that has structural or functional significance. While profiles and patterns are related concepts, motif specifically refers to the mathematical representation of these conserved sequence/structure regions.

Multiple choice

Which sequencing method is efficiently helpful for the Human Genome Project?

  1. Sanger method

  2. Maxm-Gilbert method

  3. Whole Genome Shotgun

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The Human Genome Project primarily used the Whole Genome Shotgun (WGS) sequencing approach, which involved randomly fragmenting the genome, sequencing fragments, and assembling them computationally. This was more efficient than Sanger or Maxam-Gilbert methods for large-scale genome sequencing.

Multiple choice

What type of recombination vector was generally recommended for HGP?

  1. Plasmid

  2. Cosmid

  3. BAC

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

Bacterial Artificial Chromosomes (BACs) were the primary cloning vectors recommended for the Human Genome Project because they could stably maintain large DNA inserts (100-200 kb), were easier to work with than YACs, and provided the stability needed for accurate sequencing of large genomic regions.

Multiple choice

E.coli cells with a mutated z gene of the lac operon cannot grow in medium containing only lactose as the source of the energy because

  1. they cannot synthesise functional betagalactosidase

  2. they cannot transport lactose from the medium into the cell

  3. the lac operon is constitutively active in these cells

  4. in the presence of glucose, E.coli cells do not utilize lactose
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

 E.coli cells with a mutated z gene of the lac operon cannot grow in medium containing only lactose as the source of the energy because they cannot synthesise functional betagalactosidase.

Multiple choice

Using imprints from a plate with complete medium and carrying bacterial colonies, you can select streptomycin resistant mutants and prove that such mutations do not originate as adaptation. These imprints need to be used

  1. on plates with and without streptomycin

  2. only on plates with streptomycin

  3. on plates with minimal medium

  4. only on plates without streptomycin
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

 To check resistance of mutants against streptomycin they must be grown on plates with streptomycin. Only those bacterial colonies will propagate from the master that are resistant to the antibiotic.

Multiple choice

Which of the following statements is/are correct?

  1. Bacterial cells protect their own DNA from degradation by restriction endonucleases by deleting all recognition sites from the genome.
  2. The Southern blotting technique depends on similarities between the sequences of probe RNA and experimental RNA.
  3. Vectors are molecules that protect host cells from invasion by foreign DNA.

  1. Only 1

  2. Only 2

  3. Only 3

  4. 2 and 3

  5. All of the above
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Polymerase chain reaction is a molecular technique for amplification of DNA sequences between two oligonucleotide primers. The Southern blotting technique depends on similarities between the sequences of probe DNA and experimental DNA. Vectors are molecules that are able to covalently bond to and carry foreign DNA into cells.

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

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

In the following question there are two statements, Assertion (A) and Reason (R), consider both the statements independently and mark your answers as under:
1. If A and R both are correct and R is correct explanation of A.
2. If A and R both are correct and R is not correct explanation of A.
3. If A is correct and R is incorrect.
4. If A is incorrect and R is correct.
5. If A and R both are incorrect.

  1. 1

  2. 2

  3. 3

  4. 4

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

Both Assertion (A) as well as Reason (R) are incorrect. The normal role of restriction endonucleases in bacterial cells 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 recognizes.

Multiple choice

Which antigenic particle present in the serum of individuals, infected with the virus hepatitis B, contain both DNA and DNA polymerase?

  1. A spherical 22 nm particle

  2. Dane particle

  3. Tubular or filamentous 22 m particle

  4. GP 120 envelope protein

  5. p7 nucleocapsid protein
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The virus particle consists an outer lipid envelope and an icosahedral nucleocapsid core composed of protein. These virions are 42 nm in diameter and are sometimes referred to as Dane particles. This is known as the Dane particle as it was discovered by Dane in 1970. The nucleocapsid encloses the viral DNA and a DNA polymerase that has reverse transcriptase activity.