The first instance of artificial recombinant DNA construction involved isolating a gene that conferred resistance to:

[Biotechnology-Principles-and-Processes] [class-xii ]

• Heat
• Pesticides
• Viral infection
• Antibiotics
Correct Option: D  [ Antibiotics ]

Remark: The construction involved linking a gene encoding antibiotic resistance.

A plasmid acts as a vector to transfer alien DNA, analogous to how a mosquito acts as an insect vector to transfer the _________ parasite.

[Biotechnology-Principles-and-Processes] [class-xii ]

• Bacterial
• Malarial
• Viral
• Fungal
Correct Option: B  [ Malarial ]

Remark: A mosquito acts as an insect vector to transfer the malarial parasite into the human body.

Restriction endonucleases inspect the length of a DNA sequence to find their specific:

[Biotechnology-Principles-and-Processes] [class-xii ]

• Transcription sequence
• Replication sequence
• Recognition sequence
• Translation sequence
Correct Option: C  [ Recognition sequence ]

Remark: Restriction endonucleases function by ‘inspecting’ the length of a DNA sequence to find their specific recognition sequence.

If an alien piece of DNA is linked with bacteriophage or plasmid DNA, its numbers will multiply equal to the _________ of the vector.

[Biotechnology-Principles-and-Processes] [class-xii ]

• Size
• Copy number
• Restriction sites
• Weight
Correct Option: B  [ Copy number ]

Remark: The numbers of the alien DNA will multiply equal to the copy number of the plasmid or bacteriophage.

If foreign DNA is inserted into the *ampR* gene of pBR322, the transformants would lose ampicillin resistance. To select these recombinants from non-recombinants, what medium is used for the *first* plating step?

[Biotechnology-Principles-and-Processes] [class-xii ]

• Tetracycline medium (only)
• Kanamycin medium (only)
• Ampicillin containing medium (only)
• Chloramphenicol medium (only)
Correct Option: C  [ Ampicillin containing medium (only) ]

Remark: The transformants growing on ampicillin containing medium are selected first, as non-transformants die. Loss of ampicillin resistance distinguishes recombinants in the second step.

The tumor inducing (Ti) plasmid of *Agrobacterium tumifaciens* has been modified into a cloning vector which is no longer:

[Biotechnology-Principles-and-Processes] [class-xii ]

• Hydrophilic
• Pathogenic
• Competent
• Dependent
Correct Option: B  [ Pathogenic ]

Remark: The Ti plasmid has been modified into a cloning vector which is no more pathogenic to the plants.

The heat shock method (ice $ ightarrow$ 42°C $ ightarrow$ ice) is used to enable bacteria to take up recombinant DNA because it makes the bacteria:

[Biotechnology-Principles-and-Processes] [class-xii ]

• Hydrophilic
• Asexual
• Competent
• Sterile
Correct Option: C  [ Competent ]

Remark: This procedure enables the bacteria to take up the recombinant DNA after being made ‘competent’ by divalent cations and temperature changes.

The three steps in each cycle of Polymerase Chain Reaction (PCR) are (i) Denaturation, (ii) Primer annealing, and (iii):

[Biotechnology-Principles-and-Processes] [class-xii ]

• Ligation of primers
• Digestion of primers
• Extension of primers
• Separation of primers
Correct Option: C  [ Extension of primers ]

Remark: Each PCR cycle has three steps: (i) Denaturation; (ii) Primer annealing; and (iii) Extension of primers.

The continuous culture system is primarily used in bioreactors because it maintains cells in the log/exponential phase, which leads to:

[Biotechnology-Principles-and-Processes] [class-xii ]

• Lower biomass production
• Identical yields of desired protein
• Higher yields of desired protein
• Variable mutation rates
Correct Option: C  [ Higher yields of desired protein ]

Remark: Continuous culturing produces a larger biomass leading to higher yields of desired protein.

Bioreactors are vessels in which raw materials are biologically converted into specific products using microbial, plant, animal or _________ cells.

[Biotechnology-Principles-and-Processes] [class-xii ]

• Yeast
• Fungal
• Viral
• Human
Correct Option: D  [ Human ]

Remark: Bioreactors use microbial, plant, animal or human cells.