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.
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.
Question 532 of 535
📘 CLASS XII
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'.
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.
Question 533 of 535
📘 CLASS XII
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.
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.
Question 534 of 535
📘 CLASS XII
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.
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.
Question 535 of 535
📘 CLASS XII
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.
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).
