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 botany biotechnology: principles and processes manipulation of dna electrophoresis isolation and separation of dna

Select the incorrect Statement regarding DNA replication with respect to the template strand

  1. Leading strand is formed in 5 $\rightarrow$ 3 direction.
  2. Okazaki fragments are formed in 5 $\rightarrow$ 3 direction.
  3. DNA polymerase catalyses polymerisation in 5 $\rightarrow$ 3 direction.
  4. DNA polymerase catalyses palymerisation in 3 $\rightarrow$ 5 direction.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Since DNA polymerase requires a free 3' OH group for initiation of synthesis, it can synthesize in only one direction by extending the 3' end of the preexisting nucleotide chain. Hence, DNA polymerasemoves along the template strand in a 3'–5' direction, and the daughter strand is formed in a 5'–3' direction.

So, the correct answer is 'DNA polymerase catalyses polymerisation in 5 
→→ 3 direction'

Multiple choice botany biotechnology: principles and processes manipulation of dna electrophoresis isolation and separation of dna

The sequence of strategies involved in the isolation of a gene of interest from a plant cell during the process of rDNA technology

  1. Dissolution of biological membrane

  2. Enzymatic digestion of cell wall

  3. Precipitation of DNA

  4. Removal of DNA by spoiling
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Isolation of the Genetic Material (DNA):

Nucleic acid is the genetic material, which is present in all living organisms. In majority of organisms, this is present in the form of deoxy-ribonucleic acid (DNA). DNA must be present into pure form, i.e., free from other macro-molecules (like proteins, RNA, enzymes, etc.) in order to cut the DNA with restrictor enzymes.

Isolation of genetic material (DNA) is carried out in the following steps:

(a) Since the DNA is enclosed within the membranes, so, in order to release DNA along with other macro-molecules such as proteins, polysaccharides and lipids, bacterial cells/plant or animal tissues are treated with the enzyme lysozyme (bacteria), cellulose (plant cells), chitinase (fungus), respectively.

(b) RNA can be removed by the treatment with ribonuclease, whereas proteins can be removed by the treatment with protease.

(c) Other molecules can be removed by appropriate treatments and ultimately purified DNA will precipitate out, after the addition of chilled ethanol. This can be seen as collection of fine threads in the suspension.

So, the correct answer is “Precipitation of DNA”.

Multiple choice botany biotechnology: principles and processes manipulation of dna electrophoresis isolation and separation of dna

During the process of isolation of DNA, chilled ethanol is added to

  1. Break open the cell to release DNA

  2. Facilitate action of restriction enzymes

  3. Remove proteins such as histones

  4. Precipitate DNA
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Chilled ethanol is used in DNA isolation because DNA is insoluble in ethanol, causing it to precipitate out of the solution as fine threads.

Multiple choice zoology mutation dna fingerprinting human genome project and dna fingerprinting instruments in biotechnology

Gene amplification requires besides sample DNA

  1. Nucleotides

  2. Nucleotides and polymerases

  3. Alternate heating and cooling

  4. Both B and C
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Polymerase chain reaction (PCR) is an amplification technique for cloning the specific or targeted parts of a DNA sequence to generate thousands to millions of copies of DNA of interest. This molecular “xeroxing” process involves heating and cooling samples in a precise thermal cycling pattern over ≈30 cycles. PCR uses a small amount of template DNA, two primers that flank the target sequence, nucleotides, and thermostable DNA polymerase to amplify a specific region of DNA.

So, the correct answer is 'Both B and C.'

Multiple choice zoology mutation dna fingerprinting human genome project and dna fingerprinting instruments in biotechnology

In vitro repeated replication of selected DNA components is

  1. Gene amplification

  2. Gene replication

  3. Gene synthesis

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

Gene amplification can occur in situ, forming a so-called homogeneously staining region (HSR) in the normal chromosomal location of the gene (many copies of the gene are present as tandem repeats) or as so-called double minute chromosomes (extra chromosomal fragments of DNA containing multiple copies of the amplified gene). Gene amplification can also occur as an artifact when tumor cells are cultured in vitro.

So, the correct answer is 'Gene amplification.'

Multiple choice zoology mutation dna fingerprinting human genome project and dna fingerprinting instruments in biotechnology

Select the correct sequences of steps in DNA finger printing involving Southern blot hybridisation using radiolabelled VNTR as proble
I. Hybridisation using labelled VNTR prob
II. Isolation of DNA
III. Transferring (blotting) of separated DNA fragments to synthetic membranes, such as nitrocellulose or nylon
IV. Detection of hybridised DNA fragments by autoradiography
V. Separation of DNA fragments by electropheresis
VI. Digestion of DNA by restriction endonucleases

  1. I, V, VI, II, III and IV

  2. II, VI, V, III, I and IV

  3. V, I, VI, III, IV and II

  4. II, I, V, VI, IV and III
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The correct sequence is: Isolation of DNA (II), Digestion by restriction enzymes (VI), Separation by electrophoresis (V), Transfer/blotting (III), Hybridization (I), and Detection by autoradiography (IV).

Multiple choice botany breeding and biotechnology branches of biotechnology gene cloning biotechnology and genetic engineering

In recombinant DNA technology, a plasmid vector is cleaved by

  1. Modified DNA ligase

  2. A heated allkaline solution

  3. The same enzyme that cleaves the donor DNA

  4. The different enzyme than that cleaves the donor DNA
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Answer is option C i.e. "The same enzyme that cleaves the donor DNA"
In rDNA technology, the plasmid vector must be cleaved by specific restriction enzyme. Plasmid vectors are cleaved by  same enzyme that cleaves the donor DNA leading to creation of sticky ends which further helps in recombination.

Multiple choice botany breeding and biotechnology branches of biotechnology gene cloning biotechnology and genetic engineering

Plasmids are

  1. Viruses

  2. Extra-chromosomal genetic element of bacteria

  3. New type of microorganism

  4. Genetic element of bacteria
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A plasmid is a small DNA molecule within a cell that is physically separated from a chromosomal DNA and can replicate independently. They are most commonly found in bacteria as small, circular, double-stranded DNA molecules. Plasmids carry only a few genes and exist independently of chromosomes, the primary structures that contain DNA in cells. Able to self-replicate, plasmids can be picked up from the environment and transferred between bacteria. Plasmids are used by their host organism to cope with stress-related conditions.

Therefore, the correct answer is option B.

Multiple choice botany breeding and biotechnology branches of biotechnology gene cloning biotechnology and genetic engineering

Various enzymes and hormones can be produced on a large scale by employing the recombinant __________ technique.

  1. DNA

  2. RNA

  3. Viral

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

Recombinant DNA (or rDNA) is made by combining DNA from two or more sources. In practice, the process often involves combining the DNA of different organisms. The process depends on the ability to cut and re-join DNA molecules at points which are identified by specific sequences of nucleotide bases called restriction sites. DNA fragments are cut out of their normal position in the chromosome using restriction enzymes (also called restriction endonucleases) and then inserted into other chromosomes or DNA molecules using enzymes called ligases.

Therefore, the correct answer is option A.

Multiple choice botany breeding and biotechnology branches of biotechnology gene cloning biotechnology and genetic engineering

The recent techniques used for separating fragments of DNA is

  1. Northern blotting

  2. Southern blotting

  3. Eastern blotting

  4. Western blotting
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Southern blotting is a common technique used in molecular biology to separate and characterize DNA. Southern blotting is a technique used to determine the presence of a specific DNA sequence within a mixture via agarose gel electrophoresis. The Northern blot is a technique used in molecular biology research to study gene expression by detection of RNA (or isolated mRNA) in a sample. The Eastern blot is a biochemical technique used to analyze protein post translational modifications such as lipids, phospho-moieties and glycoconjugates. Western blotting is an adaptation of the Southern blot procedure, used to identify specific amino-acid sequences in proteins.
Multiple choice zoology genetics of the future hgp and dna fingerprinting dna fingerprinting human genome project and dna fingerprinting

Fill up the blanks and select the correct option.
(i) EcoRI cuts the DNA between bases ___ only ____ when the sequence __  is present in the DNA.
(ii) Disruption of the cell membranes can be achieved by treating the bacterial cells, plant cells and fungal cells with enzymes respectively _, ____ and .
(iii) Since DNA has a _ charge, it moves towards the ____ of the electrophoretic chamber.

  1. (i) G A, GAATTC (ii) endonuclease, cellulase, chitinase (iii) negative, anode

  2. (i) G A, GAATTC (ii) lysozyme, cellulase, chitinase (iii) positive, cathode

  3. (i) G A, GAATTC (ii) lysozyme, cellulase, chitinase negative/anode

  4. (i) G A, GAAATC (ii) lysozyme, cellulase, chitinase (iii) positive, cathode
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

  • EcoRI cuts the DNA between bases G and A only when the sequence GAATTC is present in the DNA.
  • Disruption of the cell membranes can be achieved by treating the bacterial cells, plant cells and fungal cells with enzymes lysozyme, cellulase and chitinases respectively.
  • Since DNA has a negative charge , it moves towards the anode of the electrophoretic chamber.
So, the correct option is 'Option C' .

Multiple choice zoology genetics of the future hgp and dna fingerprinting dna fingerprinting human genome project and dna fingerprinting

Which one of the following pairs of terms/names mean one and the same thing?

  1. Gene pool - Genome

  2. Codon - Gene

  3. Cistron - Triplet

  4. DNA fingerprinting - DNA profiling
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

DNA profiling or fingerprinting is a technique employed by forensic scientists to assist in the identification of individuals by their respective DNA profiles.

Multiple choice zoology genetics of the future hgp and dna fingerprinting dna fingerprinting human genome project and dna fingerprinting

The technique used to increase the amount of DNA available for analysis is
I. Cloning a plasmid
II. Gel electrophoresis
III. PCR

  1. II only

  2. I and II

  3. I and III

  4. II and III

  5. I, II, and III
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
The polymerase chain reaction (PCR) is a technique used in molecular biology to amplify a single copy of DNA to millions of copies of a particular DNA sequence. 
Molecular cloning is a method used to assemble recombinant DNA molecules and to direct their replication within host organisms to increase the number of recombinant DNA molecule. Here, the DNA can be cloned in a plasmid (extracellular DNA).
Thus, the correct answer is option C.