Purified DNA ultimately precipitates out of the suspension after the addition of chilled _________.

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

• water
• glycerol
• ethanol
• acetone
Correct Option: C  [ ethanol ]

Remark: Chilled ethanol causes purified DNA to precipitate out.

The precipitated DNA, visible as fine threads in suspension, can be removed by a technique known as _________.

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

• elution
• spooling
• electrophoresis
• ligation
Correct Option: B  [ spooling ]

Remark: The DNA is removed by spooling.

Agarose gel electrophoresis is employed to check the progression of a _________ enzyme digestion.

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

• DNA ligase
• polymerase
• restriction
• reverse transcriptase
Correct Option: C  [ restriction ]

Remark: Agarose gel electrophoresis checks the progression of a restriction enzyme digestion.

The cut gene of interest and the cut vector are mixed, and the enzyme _________ is added to complete the preparation of recombinant DNA.

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

• DNA polymerase
• DNA ligase
• restriction endonuclease
• exonuclease
Correct Option: B  [ DNA ligase ]

Remark: Ligase joins the cut source DNA and the cut vector.

PCR stands for _________.

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

• Primary Chain Replication
• Polymerase Chain Reaction
• Protein Counting Ratio
• Palindromic Cloning Routine
Correct Option: B  [ Polymerase Chain Reaction ]

Remark: PCR stands for Polymerase Chain Reaction.

In PCR, multiple copies of the gene of interest are synthesised *in vitro* using two sets of primers and the enzyme _________.

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

• DNA ligase
• restriction enzyme
• DNA polymerase
• RNA transcriptase
Correct Option: C  [ DNA polymerase ]

Remark: DNA polymerase is the enzyme used in PCR.

If the replication process in PCR is repeated many times, the segment of DNA can be amplified to approximately _________ times.

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

• thousand
• million
• billion
• trillion
Correct Option: C  [ billion ]

Remark: The DNA segment can be amplified to approximately billion times (1 billion copies are made).

The thermostable DNA polymerase used in PCR is isolated from the bacterium _________.

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

• Escherichia coli
• Salmonella typhimurium
• Agrobacterium tumifaciens
• Thermus aquaticus
Correct Option: D  [ Thermus aquaticus ]

Remark: The thermostable DNA polymerase is isolated from *Thermus aquaticus*.

The thermostable DNA polymerase remains active during the high temperature induced _________ of double-stranded DNA in PCR.

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

• annealing
• denaturation
• extension
• ligation
Correct Option: B  [ denaturation ]

Remark: The enzyme remains active during high temperature induced denaturation.

If a recombinant DNA bearing a gene for resistance to an antibiotic (e.g., ampicillin) is transferred into *E. coli* cells, the host cells become transformed into _________ cells.

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

• heat-sensitive
• ampicillin-resistant
• pathogenic
• competent
Correct Option: B  [ ampicillin-resistant ]

Remark: The host cells become transformed into ampicillin-resistant cells.