Assertion (A):
In insertional inactivation using a chromogenic substrate, non-recombinant colonies appear blue.
Reason (R):
The presence of an insert results in the inactivation of the $eta$-galactosidase gene, causing the colonies to remain colorless and thus identifying them as recombinants.

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

• (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion
• (B) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion
• (C) Assertion is true but Reason is false
• (D) Assertion is false but Reason is true
Correct Option: A  [ A ]

Remark: A is True: Non-recombinants have the intact gene and produce the blue color.
R is True: The lack of color production due to insertional inactivation identifies the recombinants. R describes the mechanism that allows the differentiation based on the color status detailed in A.

Assertion (A):
We learned the lesson of transferring genes into plants and animals from studying bacteria and viruses.
Reason (R):
Pathogens like Agrobacterium tumifaciens (in plants) and retroviruses (in animals) naturally possess the ability to deliver genes to transform eukaryotic cells.

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

• (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion
• (B) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion
• (C) Assertion is true but Reason is false
• (D) Assertion is false but Reason is true
Correct Option: A  [ A ]

Remark: A is True: Knowledge of gene transfer originated from observing pathogens.
R is True: R lists the pathogens that provided this key knowledge. R explains the source of the lesson mentioned in A.

Assertion (A):
The tumor inducing ($Ti$) plasmid of Agrobacterium tumifaciens is used in its pathogenic form as a cloning vector for gene delivery into dicot plants.
Reason (R):
The Ti plasmid has been modified into a cloning vector that is no longer pathogenic but is still able to deliver genes of interest into a variety of plants.

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

• (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion
• (B) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion
• (C) Assertion is true but Reason is false
• (D) Assertion is false but Reason is true
Correct Option: D  [ D ]

Remark: A is False: The Ti plasmid must be modified to be non-pathogenic for use as a vector.
R is True: The modified Ti plasmid is non-pathogenic yet effective for gene delivery.

Assertion (A):
Bacterial cells are treated with a divalent cation like calcium to make them 'competent' to take up DNA.
Reason (R):
The calcium treatment increases the efficiency with which the DNA enters the bacterium through pores in its cell wall.

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

• (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion
• (B) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion
• (C) Assertion is true but Reason is false
• (D) Assertion is false but Reason is true
Correct Option: A  [ A ]

Remark: A is True: Divalent cations like calcium are used to induce competence.
R is True: The mechanism by which this works is by increasing the efficiency of DNA entry through cell wall pores. R explains A.

Assertion (A):
Micro-injection is a method of introducing recombinant DNA by bombarding cells with high velocity micro-particles of gold or tungsten coated with DNA.
Reason (R):
Micro-injection is suitable for plant cells, while biolistics (gene gun) is suitable for animal cells.

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

• (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion
• (B) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion
• (C) Assertion is true but Reason is false
• (D) Assertion is false but Reason is true
Correct Option: D  [ D ]

Remark: A is False: A describes biolistics or gene gun. Micro-injection involves direct injection into the nucleus of an animal cell.
R is False: Micro-injection is for animal cells; biolistics is suitable for plant cells.

Assertion (A):
In order to cut DNA with restriction enzymes, the DNA needs to be in pure form, free from other macromolecules.
Reason (R):
DNA is contained within membranes, and we must break the cell open to release DNA along with other macromolecules such as RNA, proteins, and polysaccharides.

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

• (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion
• (B) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion
• (C) Assertion is true but Reason is false
• (D) Assertion is false but Reason is true
Correct Option: B  [ B ]

Remark: A is True: DNA must be purified before restriction enzyme digestion.
R is True: Cell lysis is required to release DNA along with contaminants. Both are necessary steps, but R explains the state of DNA in the cell, not why it must be pure before cutting (A).

Assertion (A):
To isolate DNA, bacterial cells are treated with lysozyme, plant cells with cellulase, and fungal cells with chitinase.
Reason (R):
These specific enzymes are used to break down the respective cell walls to achieve the release of DNA.

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

• (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion
• (B) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion
• (C) Assertion is true but Reason is false
• (D) Assertion is false but Reason is true
Correct Option: A  [ A ]

Remark: A is True: These enzymes are correctly matched to their respective cell types.
R is True: The goal of using these enzymes is to break the cell boundaries to release DNA. R explains A.

Assertion (A):
RNA is removed from the DNA extract by treatment with ribonuclease, and proteins are removed by protease.
Reason (R):
Genes are located on long molecules of DNA intertwined with proteins such as histones.

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

• (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion
• (B) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion
• (C) Assertion is true but Reason is false
• (D) Assertion is false but Reason is true
Correct Option: B  [ B ]

Remark: A is True: Ribonuclease and protease are used for removing RNA and protein contaminants.
R is True: DNA is associated with proteins like histones. R describes the structure, but not why the contaminants must be digested (A).

Assertion (A):
Agarose gel electrophoresis is used to check the progression of a restriction enzyme digestion.
Reason (R):
After digestion, the DNA is a negatively charged molecule, and it must move towards the positive electrode (anode) under an electric field.

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

• (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion
• (B) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion
• (C) Assertion is true but Reason is false
• (D) Assertion is false but Reason is true
Correct Option: B  [ B ]

Remark: A is True: Gel electrophoresis is used to verify digestion.
R is True: DNA is negative and moves toward the anode. R describes the physical property necessary for the separation seen in A, but not why A is used to check the digestion.

Assertion (A):
In Polymerase Chain Reaction (PCR), the segment of DNA can be amplified to approximately a billion times after many repeated cycles.
Reason (R):
Such repeated amplification is achieved by using a thermostable DNA polymerase, which remains active during the high temperature denaturation steps.

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

• (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion
• (B) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion
• (C) Assertion is true but Reason is false
• (D) Assertion is false but Reason is true
Correct Option: A  [ A ]

Remark: A is True: DNA can be amplified to a billion copies in PCR.
R is True: The thermostable polymerase (like *Taq*) allows the cycles (including high heat steps) to be repeated many times efficiently, which is necessary to achieve the huge amplification mentioned in A. R explains how A is achieved.