The use of two antibiotic resistance genes in selection is a cumbersome procedure that requires simultaneous plating on _________ plates having different antibiotics.

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

• one
• two
• three
• four
Correct Option: B  [ two ]

Remark: Selection using antibiotic inactivation requires simultaneous plating on two plates.

Alternative selectable markers differentiate recombinants based on their ability to produce _________ in the presence of a chromogenic substrate.

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

• heat
• light
• colour
• antibiotics
Correct Option: C  [ colour ]

Remark: Alternative markers use the basis of producing colour.

In chromogenic selection, insertional inactivation occurs within the coding sequence of the enzyme _________.

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

• DNA ligase
• RNA polymerase
• beta-galactosidase
• protease
Correct Option: C  [ beta-galactosidase ]

Remark: The insertion targets the coding sequence of the enzyme $\beta$-galactosidase.

If a plasmid does not have an insert (non-recombinant), the presence of a chromogenic substrate gives _________ coloured colonies.

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

• white
• blue
• orange
• red
Correct Option: B  [ blue ]

Remark: Non-recombinant colonies produce blue colour.

If a plasmid has an insert (recombinant), insertional inactivation occurs, and the colonies do not produce any colour, often appearing _________.

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

• blue
• orange
• colourless
• brown
Correct Option: C  [ colourless ]

Remark: Recombinant colonies do not produce any colour due to insertional inactivation of $\beta$-galactosidase.

The pathogen of several dicot plants used as a source for gene transfer vectors is _________.

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

• Escherichia coli
• Salmonella typhimurium
• Agrobacterium tumifaciens
• Retrovirus
Correct Option: C  [ Agrobacterium tumifaciens ]

Remark: *Agrobacterium tumifaciens* is a pathogen of dicot plants used for transferring genes.

Agrobacterium tumifaciens delivers a piece of DNA known as _________ to transform normal plant cells into a tumor.

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

• Ti plasmid
• T-DNA
• cDNA
• ori sequence
Correct Option: B  [ T-DNA ]

Remark: It delivers a piece of DNA known as 'T-DNA'.

In animals, _________ have the ability to transform normal cells into cancerous cells and have been disarmed for use as vectors.

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

• plasmids
• bacteriophages
• retroviruses
• Ti plasmids
Correct Option: C  [ retroviruses ]

Remark: Retroviruses in animals have been disarmed and are now used to deliver desirable genes.

The modified cloning vector derived from *Agrobacterium tumifaciens* is the _________ plasmid.

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

• pBR322
• Ti
• Pst I
• Sal I
Correct Option: B  [ Ti ]

Remark: The tumor inducing (Ti) plasmid has been modified into a cloning vector.

Since DNA is a _________ molecule, it cannot pass through cell membranes easily.

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

• hydrophobic
• hydrophilic
• amphipathic
• lipophilic
Correct Option: B  [ hydrophilic ]

Remark: DNA is a hydrophilic molecule.