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Topic Question Set

Q 1 :

The following diagram showing restriction sites in E. coli cloning vector or pBR322. Find the role of 'X' and 'Y' genes.       [2024]

  • The gene ‘X’ is responsible for resistance to antibiotics and ‘Y’ for protein involved in the replication of Plasmid.

     

  • The gene ‘Y’ is responsible for controlling the copy number of the linked DNA and ‘Y’ for protein involved in the replication of Plasmid.

     

  • The gene ‘X’ is for protein involved in replication of Plasmid and ‘Y’ for resistance to antibiotics.

     

  • Gene ‘X’ is responsible for recognition sites and ‘Y’ is responsible for antibiotic resistance.

     

(2)

In the given diagram showing restriction sites in E.coli cloning vector pBR322, X and Y represent ori and rop, respectively. The gene ‘X’ is responsible for controlling the copy number of the linked DNA and ‘Y’ for protein involved in the replication of plasmid.

 

Q 2 :

The “Ti plasmid” of Agrobacterium tumefaciens stands for               [2024]

  • tumor inhibiting plasmid

     

  • tumor independent plasmid

     

  • tumor inducing plasmid

     

  • temperature independent plasmid

     

(3)

‘Ti plasmid’ of Agrobacterium tumefaciens stands for tumour inducing plasmid. The tumour inducing (Ti) plasmid of Agrobacterium tumefaciens has been modified into cloning vector which is not pathogenic to the plants, however, it is still able to use its mechanisms to deliver genes of our interest into various plants.

 

Q 3 :

Hind II always cuts DNA molecules at a particular point called recognition sequence and it consists of            [2024]

  • 8 bp

     

  • 6 bp

     

  • 4 bp

     

  • 10 bp

     

(2)

Hind II was the first discovered restriction endonuclease enzyme. It was isolated from bacterium Haemophilus influenzae Rd. It cuts DNA molecules at a particular point by recognising a specific sequence of six base pairs. This specific sequence is known as the recognition sequence for Hind II. It produces blunt ends.

 

Q 4 :

Ligation of foreign DNA at which of the following site will result in loss of tetracycline resistance of pBR322?               [2023]

  • Pst I

     

  • Pvu I

     

  • EcoR I

     

  • BamH I

     

(4)

In the plasmid vectors, pBR322, tetracycline resistance gene contains recognition sites for two restriction enzymes BamH I and Sal I. The recombinant plasmids will lose tetracycline resistance due to insertion of foreign DNA at one of these sites.

 

Q 5 :

Which of the following statements is incorrect about Agrobacterium tumefaciens?                [2023]

  • It is used to deliver gene of interest in both prokaryotic as well as eukaryotic host cells.

     

  • ‘Ti’ plasmid from Agrobacterium tumefaciens used for gene transfer is not pathogenic to plant cell.

     

  • It transforms normal plant cells into tumor cells.

     

  • It delivers ‘T-DNA’ into plant cell.

     

(1)

Ti plasmid (tumour inducing) from the soil bacterium Agrobacterium tumefaciens is effectively used as vector for gene transfer to eukaryotic (plant) cells. The part of Ti plasmid transferred into plant cell DNA is called the T-DNA.

 

Q 6 :

Match List I with List II.                                                                               [2023]

  List I   List II
(A) Kanamycin (I) Delivers genes into animal cells
(B) Cla I (II) Selectable marker
(C) Disarmed retroviruses (III) Restriction site
(D) KanamycinR gene (IV) Antibiotic resistance

 

Choose the correct answer from the options given below:

  • (A)-(II), (B)-(III), (C)-(I), (D)-(IV)

     

  • (A)-(III), (B)-(I), (C)-(IV), (D)-(II)

     

  • (A)-(IV), (B)-(III), (C)-(I), (D)-(II)

     

  • (A)-(II), (B)-(IV), (C)-(I), (D)-(III)

     

(1)

 

Q 7 :

Upon exposure to UV radiation, DNA stained with ethidium bromide will show               [2023]

  • bright yellow colour

     

  • bright orange colour

     

  • bright red colour

     

  • bright blue colour

     

(2)

The DNA fragments separated by gel electrophoresis can be visualised after staining the DNA with ethidium bromide followed by exposure to UV radiations. Bands of DNA are seen as bright orange coloured bands in ethidium bromide stained gel exposed to UV light.

 

Q 8 :

In gene gun method used to introduce alien DNA into host cells, microparticles of ________ metal are used.         [2023]

  • tungsten or gold

     

  • silver

     

  • copper

     

  • zinc

     

(1)

In biolistics or gene gun method, cells are bombarded with high velocity micro-particles of gold or tungsten coated with DNA.

 

Q 9 :

Which of the following is not a cloning vector?                          [2023]

  • pBR322

     

  • Probe

     

  • BAC

     

  • YAC

     

(2)

Cloning vectors are DNA molecules into which foreign DNA can be introduced and transmitted to host cell for use in cloning. Different types of cloning vectors are plasmids, bacteriophages, BAC, YAC. A probe is single stranded sequence of DNA or RNA used to identify complementary sequence in genome.

 

Q 10 :

Which one of the following statements is not true regarding gel electrophoresis technique?                 [2022]

  • The process of extraction of separated DNA strands from gel is called elution.

     

  • The separated DNA fragments are stained by using ethidium bromide.

     

  • The presence of chromogenic substrate gives blue coloured DNA bands on the gel.

     

  • Bright orange coloured bands of DNA can be observed in the gel when exposed to UV light.

     

(3)

In gel electrophoresis, the DNA fragments separate according to their size through the agarose gel, with smaller fragments moving farther away as compared to larger ones. The orange coloured bands of DNA can be visualised by staining them with ethidium bromide followed by exposure to UV radiations. The separated bands of DNA are cut out from the agarose gel is called elution.

 

Q 11 :

In the following palindromic base sequences of DNA, which one can be cut easily by a particular restriction enzyme?          [2022]

  • 5′ G A T A C T 3′ ; 3′ C T A T G A 5′

     

  • 5′ G A A T T C 3′ ; 3′ C T T A A G 5′

     

  • 5′ C T C A G T 3′ ; 3′ G A G T C A 5′

     

  • 5′ G T A T T C 3′ ; 3′ C A T A A G 5′

     

(2)

 

Q 12 :

Given below are two statements:                                                                                            [2022]
Statement I: Restriction endonucleases recognise specific sequence to cut DNA known as palindromic nucleotide sequence.
Statement II: Restriction endonucleases cut the DNA strand a little away from the centre of the palindromic site.

In the light of the above statements, choose the most appropriate answer from the options given below:

  • Both Statement I and Statement II are correct.

     

  • Both Statement I and Statement II are incorrect.

     

  • Statement I is correct but Statement II is incorrect.

     

  • Statement I is incorrect but Statement II is correct.

     

(1)

 

Q 13 :

Which of the following is not a desirable feature of a cloning vector?                     [2022]

  • Presence of origin of replication

     

  • Presence of a marker gene

     

  • Presence of single restriction enzyme site

     

  • Presence of two or more recognition sites

     

(4)

In order to link alien DNA, the vector needs to have preferable single recognition site for commonly used restriction enzyme. Presence of more than one recognition sites within vector will generate several fragments and will complicate the gene cloning.

 

Q 14 :

DNA strands on a gel stained with ethidium bromide when viewed under UV radiation, appear as              [2021]

  • bright blue bands

     

  • yellow bands

     

  • bright orange bands

     

  • dark red bands

     

(3)

In the process of gel electrophoresis, the separated DNA fragments can be seen after staining the DNA with a compound like ethidium bromide (EtBr) followed by exposure to UV radiation as bright orange coloured bands.

 

Q 15 :

Plasmid pBR322 has PstI restriction enzyme site within gene ampR that confers ampicillin resistance. If this enzyme is used for inserting a gene for β-galactoside production and the recombinant plasmid is inserted in an E. coli strain.                   [2021]

  • It will be able to produce a novel protein with dual ability.

     

  • It will not be able to confer ampicillin resistance to the host cell.

     

  • The transformed cells will have the ability to resist ampicillin as well as produce β-galactoside.

     

  • It will lead to lysis of host cell.

     

(2)

 

Q 16 :

A specific recognition sequence identified by endonucleases to make cuts at specific positions within the DNA is              [2021]

  • poly (A) tail sequences

     

  • degenerate primer sequence

     

  • okazaki sequences

     

  • palindromic nucleotide sequences

     

(4)

A restriction endonuclease recognises a specific palindromic nucleotide sequence to make a cut at specific position within the DNA.

 

Q 17 :

Identify the wrong statement with regard to restriction enzymes.                   [2020]

  • Each restriction enzyme functions by inspecting the length of a DNA sequence.

     

  • They cut the strand of DNA at palindromic sites.

     

  • They are useful in genetic engineering.

     

  • Sticky ends can be joined by using DNA ligases.

     

(4)

 

Q 18 :

Choose the correct pair from the following.                     [2020]

  • Ligases - Join the two DNA molecules

     

  • Polymerases - Break the DNA into fragments

     

  • Nucleases - Separate the two strands of DNA

     

  • Exonucleases - Make cuts at specific positions within DNA

     

(1)

 

Q 19 :

The specific palindromic sequence which is recognised by EcoRI is            [2020]

  • 5′ - GAATTC - 3′ ; 3′ - CTTAAG - 5′

     

  • 5′ - GGAACC - 3′ ; 3′ - CCTTGG - 5′

     

  • 5′ - CTTAAG - 3′ ; 3′ - GAATTC - 5′

     

  • 5′ - GGATCC - 3′ ; 3′ - CCTAGG - 5′

     

(1)

The palindromes in DNA are base pair sequences that are same when read forward (left to right) or backward (right to left) from a central axis of symmetry.
Thus, GAATTCCTTAAG is a palindromic sequence which is recognised by EcoRI.

 

Q 20 :

The sequence that controls the copy number of the linked DNA in the vector, is termed           [2020]

  • selectable marker

     

  • Ori site

     

  • palindromic sequence

     

  • recognition site

     

(2)

Ori site is a sequence from where replication starts and any piece of DNA when linked to this sequence can be made to replicate within the host cells. This sequence is also responsible for controlling the copy number of the linked DNA in the vector. So, if one wants to recover many copies of the target DNA it should be cloned in a vector whose origin support high copy number.

 

Q 21 :

In gel electrophoresis, separated DNA fragments can be visualized with the help of          [2020]

  • acetocarmine in bright blue light

     

  • ethidium bromide in UV radiation

     

  • acetocarmine in UV radiation

     

  • ethidium bromide in infrared radiation

     

(2)

In gel electrophoresis, separated DNA fragments can be visualised only after staining the DNA with a compound i.e., ethidium bromide and followed by exposure to UV radiation as bright orange coloured bands.

 

Q 22 :

Following statements describe the characteristics of the enzyme restriction endonuclease. Identify the incorrect statement.              [2019]

  • The enzyme recognises a specific palindromic nucleotide sequence in the DNA.

     

  • The enzyme cuts DNA molecule at identified position within the DNA.

     

  • The enzyme binds DNA at specific sites and cuts only one of the two strands.

     

  • The enzyme cuts the sugar-phosphate backbone at specific sites on each strand.

     

(3)

The restriction endonuclease enzyme inspects the length of a DNA sequence. Once it recognises specific sequence, it binds to the DNA and cuts each of the two strands of the double helix at specific points in their sugar phosphate backbone. Special sequence in the DNA recognised by restriction endonuclease is called palindromic nucleotide sequence.

 

Q 23 :

A selectable marker is used to                                  [2019]

  • help in eliminating the non-transformants, so that the transformants can be regenerated

     

  • identify the gene for a desired trait in an alien organism

     

  • select a suitable vector for transformation in a specific crop

     

  • mark a gene on a chromosome for isolation using restriction enzyme.

     

(1)

 

Q 24 :

Given below are four statements pertaining to separation of DNA fragments using gel electrophoresis. Identify the incorrect statements.

(i) DNA is negatively charged molecule and so it is loaded on gel towards the anode terminal.
(ii) DNA fragments travel along the surface of the gel whose concentration does not affect movement of DNA.
(iii) Smaller the size of DNA fragment larger is the distance it travels through it.
(iv) Pure DNA can be visualized directly by exposing UV radiation.

Choose correct answer from the options given below:                                                                         [2019]

  • (i), (iii) and (iv)

     

  • (i), (ii) and (iii)

     

  • (ii), (iii) and (iv)

     

  • (i), (ii) and (iv)

     

(4)

DNA is a negatively charged molecule, so they can be separated by forcing them to move towards the anode under an electric field. DNA fragments separate according to size through the pores of agarose gel. The separated DNA fragments can be visualised only after staining the DNA with a compound known as ethidium bromide then followed by exposure to UV radiation.

 

Q 25 :

Which of the following is commonly used as a vector for introducing a DNA fragment in human lymphocytes?                 [2018]

  • Retrovirus

     

  • Ti plasmid

     

  • λ phage

     

  • pBR322

     

(1)

Retroviruses cause cancer in animals including humans. So modified retroviruses are used to transfer desirable genes into animal cells. It is used in gene therapy, in which lymphocytes from blood of patient are taken and grown in culture medium outside the body, a functional gene is introduced by using a retroviral vector into these lymphocytes which are again reintroduced into the patient body.

 

Q 26 :

The DNA fragments separated on an agarose gel can be visualised after staining with                      [2017]

  • acetocarmine

     

  • aniline blue

     

  • ethidium bromide

     

  • bromophenol blue

     

(3)

The separated DNA fragments can be seen only after staining them with a compound known as ethidium bromide (EtBr) followed by exposure to UV radiation as bright orange coloured bands.

 

Q 27 :

DNA fragments are                            [2017]

  • negatively charged

     

  • neutral

     

  • either positively or negatively charged depending on their size

     

  • positively charged

     

(1)

 

Q 28 :

A gene whose expression helps to identify transformed cell is known as                  [2017]

  • vector

     

  • plasmid

     

  • structural gene

     

  • selectable marker

     

(4)

Some genes called "selectable markers" help in selecting those host cells which contain the vectors (transformants) and eliminating the non-transformants.

 

Q 29 :

What is the criterion for DNA fragments movement on agarose gel during gel electrophoresis?              [2017]

  • The smaller the fragment size, the farther it moves.

     

  • Positively charged fragments move to farther end.

     

  • Negatively charged fragments do not move.

     

  • The larger the fragment size, the farther it moves

     

(1)

Electrophoresis is a technique used for the separation of substances of different ionic properties. Since the DNA fragments are negatively charged molecules, they can be separated by allowing them to move towards the anode. DNA fragments move towards the anode according to their molecule size through the pores of agarose gel. Thus, the smaller fragments move farther away as compared to larger fragments.

 

Q 30 :

A foreign DNA and plasmid cut by the same restriction endonuclease can be joined to form a recombinant plasmid using          [2016]

  • EcoRI

     

  • Taq polymerase

     

  • polymerase III

     

  • ligase

     

(4)

Ligase is a class of enzymes that catalyse the formation of covalent bonds using the energy released by the cleavage of ATP. Ligases are important in the synthesis and repair of many biological molecules, including DNA ligase and used in genetic engineering to insert foreign DNA into cloning vectors.