Assertion (A):
Traditional hybridisation procedures often lead to the inclusion and multiplication of undesirable genes along with the desired genes.
Reason (R):
The techniques of genetic engineering overcome this limitation by allowing the introduction of only one or a set of desirable genes into the target organism.

[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: Traditional methods include undesirable genes.
R is True: Genetic engineering allows selective introduction of desired genes. Both are true statements about the two techniques, but R describes the *solution*, not the *cause* of the problem stated in A.

Assertion (A):
An alien piece of DNA, when transferred into an organism, would most likely not be able to multiply itself in the progeny cells of the host.
Reason (R):
For multiplication, the alien DNA must become part of a chromosome that possesses the specific sequence known as the 'origin of replication'.

[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: Alien DNA usually cannot multiply unless integrated.
R is True: Replication is initiated by and dependent on linking to the origin of replication. R explains the fundamental requirement that makes A true.

Assertion (A):
If a recombinant DNA bearing a gene for ampicillin resistance is transferred into E. coli cells, the host cells become transformed into ampicillin-resistant cells.
Reason (R):
The normal E. coli cells do not carry resistance against antibiotics such as ampicillin, making the resistance gene a useful selectable marker.

[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: Transformation introduces resistance.
R is True: The gene is useful because normal E. coli lacks resistance. R explains the functional principle that allows the selection described in A.

Assertion (A):
The purified DNA that precipitates out after appropriate treatment and addition of chilled ethanol can be removed by a process called spooling.
Reason (R):
RNA is removed by treatment with ribonuclease and proteins by protease before the precipitation step.

[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: Spooling removes precipitated DNA [41, Figure 9.5].
R is True: Contaminants like RNA and protein are removed chemically prior to precipitation. Both are correct facts about DNA purification, but R describes prerequisite steps, not the mechanism or purpose of A.

Assertion (A):
The downstream processing and quality control testing procedures vary from product to product.
Reason (R):
The processes in downstream processing include separation, purification, formulation with preservatives, and clinical trials.

[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: DSP and quality control testing procedures vary.
R is True: R lists the components of the DSP process. R defines the process A refers to, but does not explain *why* the procedures vary (A).