NEET Biology Biotechnology Principles and Processes MCQs Set 04

Answer: (d) c, d and e

Explanation:
1. GM crops are more tolerant to abiotic stress, golden rice is rich in beta carotene (vitamin A) and disarmed retroviruses, not Agrobacterium, deliver genes to animal cells, so c, d and e are incorrect.

Teacher's Note:
1. Insertional inactivation of beta-galactosidase lets recombinants be recognised as colourless colonies, whereas non-recombinants give blue colonies with a chromogenic substrate.
2. Delivery methods: heat shock, microinjection (animal cells), biolistics or gene gun (plants) and disarmed Ti plasmid of Agrobacterium (dicots).

Answer: (a) Exonuclease

Explanation:
1. Exonucleases remove nucleotides from the ends of DNA.

Teacher's Note:
1. Recombinant DNA technology tools: restriction enzymes (molecular scissors, cut at palindromic sites), DNA ligase (joins fragments), cloning vectors (plasmids with ori, selectable markers and cloning sites) and competent host cells.
2. Names of restriction enzymes: first letter from genus, next two from species, then strain and Roman numeral for order of isolation (EcoRI from Escherichia coli RY13).

Answer: (b) Insertional inactivation

Explanation:
1. Inactivation of a gene by inserting recombinant DNA in its coding sequence is insertional inactivation.

Teacher's Note:
1. PCR needs a DNA template, two primers, dNTPs and thermostable Taq polymerase (from Thermus aquaticus), with cycles of denaturation (about 94 C), annealing and extension.
2. Gel electrophoresis separates negatively charged DNA towards the anode through agarose, by size (sieving effect); bands are seen with ethidium bromide under UV and cut out for elution.

Answer: (a) Palindrome

Explanation:
1. Words or sequences reading the same forward and backward form a palindrome.

Teacher's Note:
1. Insertional inactivation of beta-galactosidase lets recombinants be recognised as colourless colonies, whereas non-recombinants give blue colonies with a chromogenic substrate.
2. Delivery methods: heat shock, microinjection (animal cells), biolistics or gene gun (plants) and disarmed Ti plasmid of Agrobacterium (dicots).

Answer: (b) Sticky ends

Explanation:
1. EcoRI cuts the two strands a little away from the centre of the palindrome, leaving sticky ends.

Teacher's Note:
1. Recombinant DNA technology tools: restriction enzymes (molecular scissors, cut at palindromic sites), DNA ligase (joins fragments), cloning vectors (plasmids with ori, selectable markers and cloning sites) and competent host cells.
2. Names of restriction enzymes: first letter from genus, next two from species, then strain and Roman numeral for order of isolation (EcoRI from Escherichia coli RY13).

Answer: (d) Ori

Explanation:
1. The ori sequence controls the copy number of the linked DNA.

Teacher's Note:
1. PCR needs a DNA template, two primers, dNTPs and thermostable Taq polymerase (from Thermus aquaticus), with cycles of denaturation (about 94 C), annealing and extension.
2. Gel electrophoresis separates negatively charged DNA towards the anode through agarose, by size (sieving effect); bands are seen with ethidium bromide under UV and cut out for elution.

Answer: (a) Sieving effect

Explanation:
1. Smaller DNA fragments move faster through the gel pores, called the sieving effect.

Teacher's Note:
1. Insertional inactivation of beta-galactosidase lets recombinants be recognised as colourless colonies, whereas non-recombinants give blue colonies with a chromogenic substrate.
2. Delivery methods: heat shock, microinjection (animal cells), biolistics or gene gun (plants) and disarmed Ti plasmid of Agrobacterium (dicots).

Answer: (c) Downstream processing

Explanation:
1. Separation, purification and formulation of the product is downstream processing.

Teacher's Note:
1. Recombinant DNA technology tools: restriction enzymes (molecular scissors, cut at palindromic sites), DNA ligase (joins fragments), cloning vectors (plasmids with ori, selectable markers and cloning sites) and competent host cells.
2. Names of restriction enzymes: first letter from genus, next two from species, then strain and Roman numeral for order of isolation (EcoRI from Escherichia coli RY13).

Answer: (c) PCR

Explanation:
1. PCR amplifies a DNA molecule to many copies.

Teacher's Note:
1. PCR needs a DNA template, two primers, dNTPs and thermostable Taq polymerase (from Thermus aquaticus), with cycles of denaturation (about 94 C), annealing and extension.
2. Gel electrophoresis separates negatively charged DNA towards the anode through agarose, by size (sieving effect); bands are seen with ethidium bromide under UV and cut out for elution.

Answer: (c) DNA finger printing

Explanation:
1. DNA fingerprinting, based on VNTR polymorphism, is the best way to determine paternity.

Teacher's Note:
1. Insertional inactivation of beta-galactosidase lets recombinants be recognised as colourless colonies, whereas non-recombinants give blue colonies with a chromogenic substrate.
2. Delivery methods: heat shock, microinjection (animal cells), biolistics or gene gun (plants) and disarmed Ti plasmid of Agrobacterium (dicots).

Answer: (b) Agrobacterium tumefaciens

Explanation:
1. The Ti (tumour inducing) plasmid is present in Agrobacterium tumefaciens.

Teacher's Note:
1. Recombinant DNA technology tools: restriction enzymes (molecular scissors, cut at palindromic sites), DNA ligase (joins fragments), cloning vectors (plasmids with ori, selectable markers and cloning sites) and competent host cells.
2. Names of restriction enzymes: first letter from genus, next two from species, then strain and Roman numeral for order of isolation (EcoRI from Escherichia coli RY13).

Answer: (a) Plasmid

Explanation:
1. A circular extrachromosomal DNA of a bacterial cell is a plasmid.

Teacher's Note:
1. PCR needs a DNA template, two primers, dNTPs and thermostable Taq polymerase (from Thermus aquaticus), with cycles of denaturation (about 94 C), annealing and extension.
2. Gel electrophoresis separates negatively charged DNA towards the anode through agarose, by size (sieving effect); bands are seen with ethidium bromide under UV and cut out for elution.

Answer: (a) hydrophilic

Explanation:
1. DNA is a hydrophilic, large and charged molecule and cannot pass through the cell membrane.

Teacher's Note:
1. Insertional inactivation of beta-galactosidase lets recombinants be recognised as colourless colonies, whereas non-recombinants give blue colonies with a chromogenic substrate.
2. Delivery methods: heat shock, microinjection (animal cells), biolistics or gene gun (plants) and disarmed Ti plasmid of Agrobacterium (dicots).

Answer: (b) Stirred tank bioreactor

Explanation:
1. A stirred tank bioreactor is cylindrical or has a curved base for better mixing.

Teacher's Note:
1. Recombinant DNA technology tools: restriction enzymes (molecular scissors, cut at palindromic sites), DNA ligase (joins fragments), cloning vectors (plasmids with ori, selectable markers and cloning sites) and competent host cells.
2. Names of restriction enzymes: first letter from genus, next two from species, then strain and Roman numeral for order of isolation (EcoRI from Escherichia coli RY13).

Answer: (a) DNA ligase

Explanation:
1. Stickiness of the ends helps DNA ligase to join the fragments.

Teacher's Note:
1. PCR needs a DNA template, two primers, dNTPs and thermostable Taq polymerase (from Thermus aquaticus), with cycles of denaturation (about 94 C), annealing and extension.
2. Gel electrophoresis separates negatively charged DNA towards the anode through agarose, by size (sieving effect); bands are seen with ethidium bromide under UV and cut out for elution.

Answer: (a) Small chemically synthesized oligonucleotide that are complementary to region of DNA

Explanation:
1. Primers are small chemically synthesised oligonucleotides complementary to a region of the DNA.

Teacher's Note:
1. Recombinant DNA technology tools: restriction enzymes (molecular scissors, cut at palindromic sites), DNA ligase (joins fragments), cloning vectors (plasmids with ori, selectable markers and cloning sites) and competent host cells.
2. Names of restriction enzymes: first letter from genus, next two from species, then strain and Roman numeral for order of isolation (EcoRI from Escherichia coli RY13).

Answer: (a) Agarose gel

Explanation:
1. Agarose gel provides the sieving effect in electrophoresis.

Teacher's Note:
1. PCR needs a DNA template, two primers, dNTPs and thermostable Taq polymerase (from Thermus aquaticus), with cycles of denaturation (about 94 C), annealing and extension.
2. Gel electrophoresis separates negatively charged DNA towards the anode through agarose, by size (sieving effect); bands are seen with ethidium bromide under UV and cut out for elution.

Answer: (a) Biolistics method

Explanation:
1. Biolistics (gene gun) is the vectorless gene transfer method commonly used for plants.

Teacher's Note:
1. Insertional inactivation of beta-galactosidase lets recombinants be recognised as colourless colonies, whereas non-recombinants give blue colonies with a chromogenic substrate.
2. Delivery methods: heat shock, microinjection (animal cells), biolistics or gene gun (plants) and disarmed Ti plasmid of Agrobacterium (dicots).

Answer: (b) DNA ligase

Explanation:
1. DNA ligase joins the antibiotic resistance gene to the plasmid vector.

Teacher's Note:
1. Recombinant DNA technology tools: restriction enzymes (molecular scissors, cut at palindromic sites), DNA ligase (joins fragments), cloning vectors (plasmids with ori, selectable markers and cloning sites) and competent host cells.
2. Names of restriction enzymes: first letter from genus, next two from species, then strain and Roman numeral for order of isolation (EcoRI from Escherichia coli RY13).

Answer: (b) Elution

Explanation:
1. Cutting the DNA band out of the gel and extracting it is elution.

Teacher's Note:
1. PCR needs a DNA template, two primers, dNTPs and thermostable Taq polymerase (from Thermus aquaticus), with cycles of denaturation (about 94 C), annealing and extension.
2. Gel electrophoresis separates negatively charged DNA towards the anode through agarose, by size (sieving effect); bands are seen with ethidium bromide under UV and cut out for elution.

Answer: (b) Recombinant protein

Explanation:
1. A protein encoded by a gene expressed in a heterologous host is a recombinant protein.

Teacher's Note:
1. Insertional inactivation of beta-galactosidase lets recombinants be recognised as colourless colonies, whereas non-recombinants give blue colonies with a chromogenic substrate.
2. Delivery methods: heat shock, microinjection (animal cells), biolistics or gene gun (plants) and disarmed Ti plasmid of Agrobacterium (dicots).

Answer: (a) Thermostable DNA polymerase

Explanation:
1. PCR uses a thermostable DNA polymerase such as Taq polymerase.

Teacher's Note:
1. Recombinant DNA technology tools: restriction enzymes (molecular scissors, cut at palindromic sites), DNA ligase (joins fragments), cloning vectors (plasmids with ori, selectable markers and cloning sites) and competent host cells.
2. Names of restriction enzymes: first letter from genus, next two from species, then strain and Roman numeral for order of isolation (EcoRI from Escherichia coli RY13).

Answer: (a) Blue colour in the presence of X-gal

Explanation:
1. A plasmid without an insert makes active enzyme, giving blue colour with X-gal.

Teacher's Note:
1. PCR needs a DNA template, two primers, dNTPs and thermostable Taq polymerase (from Thermus aquaticus), with cycles of denaturation (about 94 C), annealing and extension.
2. Gel electrophoresis separates negatively charged DNA towards the anode through agarose, by size (sieving effect); bands are seen with ethidium bromide under UV and cut out for elution.

Answer: (a) Disarmed retrovirus

Explanation:
1. A disarmed retrovirus is used to deliver desirable genes into animal cells.

Teacher's Note:
1. Insertional inactivation of beta-galactosidase lets recombinants be recognised as colourless colonies, whereas non-recombinants give blue colonies with a chromogenic substrate.
2. Delivery methods: heat shock, microinjection (animal cells), biolistics or gene gun (plants) and disarmed Ti plasmid of Agrobacterium (dicots).

Answer: (d) None of the above

Explanation:
1. A normal E. coli cell does not carry resistance genes against these antibiotics.

Teacher's Note:
1. PCR needs a DNA template, two primers, dNTPs and thermostable Taq polymerase (from Thermus aquaticus), with cycles of denaturation (about 94 C), annealing and extension.
2. Gel electrophoresis separates negatively charged DNA towards the anode through agarose, by size (sieving effect); bands are seen with ethidium bromide under UV and cut out for elution.