Assertion (A):
Gene therapy involving the infusion of genetically engineered lymphocytes is considered a definitive, permanent cure for ADA deficiency.
Reason (R):
The only permanent cure for ADA deficiency is the introduction of the gene isolated from marrow cells producing ADA into cells at an early embryonic stage.

[Biotechnology-and-its-Applications] [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: Periodic infusion of engineered lymphocytes is required because the cells are not immortal, so it is not a permanent cure.
R is True: A permanent cure requires introducing the ADA gene into cells during early embryonic stages, allowing the modified cells to become part of the body's permanent tissue.

Assertion (A):
ELISA is a reliable technique for the early detection of diseases caused by pathogens.
Reason (R):
ELISA is based on the principle of antigen-antibody interaction, allowing detection of the pathogen (antigen) or the specific antibodies synthesized against it.

[Biotechnology-and-its-Applications] [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: Early detection is crucial for effective treatment, which is often impossible using conventional methods like serum and urine analysis.
ELISA (Enzyme Linked Immuno-sorbent Assay) utilizes the specific binding of antigens and antibodies to identify infection by detecting either the foreign proteins (antigens) or the immune response (antibodies) generated by the host.

Assertion (A):
Transgenic animals are designed to increase our understanding of how genes contribute to the development of human diseases.
Reason (R):
Transgenic animals serve as models for human diseases like cancer, cystic fibrosis, rheumatoid arthritis, and Alzheimer’s, facilitating the investigation of new treatments.

[Biotechnology-and-its-Applications] [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: Transgenic animals are genetically manipulated to mimic specific human disease conditions.
By observing the effects of altered genes, scientists can better understand the mechanism of diseases and test the efficacy and safety of potential therapies.

Assertion (A):
To produce human insulin using rDNA technology, Eli Lilly introduced the DNA sequences for chains A and B separately into E. coli.
Reason (R):
Producing insulin as a single pro-hormone in bacteria and then processing it was chemically complex, so separate chain production simplified the maturation step.

[Biotechnology-and-its-Applications] [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: The challenge in rDNA insulin production was getting the molecule assembled correctly (removal of C-peptide).
Eli Lilly overcame this by separately creating DNA sequences for the A and B chains, growing them in E. coli, extracting them, and then combining them externally by creating disulphide bonds to form mature human insulin.

Assertion (A):
Genetic modification of organisms can have unpredictable results when such organisms are introduced into the ecosystem.
Reason (R):
The Indian government established GEAC (Genetic Engineering Approval Committee) to validate GM research and ensure the safety of introducing GM organisms for public services.

[Biotechnology-and-its-Applications] [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: Unregulated genetic manipulation raises serious ethical and biological concerns due to the potential for unpredictable ecological impacts.
GEAC was established specifically to regulate such activities, ensuring the safety and validity of research involving GM organisms before they are released for public service.

Assertion (A):
Industrialized nations are typically rich in biodiversity and traditional knowledge.
Reason (R):
Biopiracy involves the unauthorized exploitation of bio-resources and associated traditional knowledge, primarily affecting developing countries, by multinational companies without compensatory payment.

[Biotechnology-and-its-Applications] [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: Industrialized nations are generally poor in biodiversity and traditional knowledge, while developing nations are rich in both.
R is True: Biopiracy is defined as the unauthorized use of bio-resources and associated traditional knowledge of concerned countries and people, especially the bio-resource rich developing nations, without proper authorization or payment.

Assertion (A):
The Bt toxin protein, when ingested by an insect, binds to the surface of midgut epithelial cells.
Reason (R):
Binding of the activated toxin creates pores in the cell surface, leading to cell swelling and lysis, which eventually causes the death of the insect.

[Biotechnology-and-its-Applications] [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: When the inactive protoxin is activated by the alkaline pH of the insect gut, it becomes soluble and binds to the midgut epithelial cells.
This binding action leads to pore formation, causing osmotic lysis of the cells and resulting in the death of the insect pest.

Assertion (A):
Transgenic animals are used for chemical safety testing, also known as toxicity testing.
Reason (R):
These transgenic animals are engineered to be more sensitive to toxic substances than non-transgenic animals, allowing results to be obtained in less time.

[Biotechnology-and-its-Applications] [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: Transgenic animals are engineered to carry genes that make them highly sensitive to toxins.
Exposure to toxic substances yields observable effects rapidly in these sensitive models, significantly accelerating the process of toxicity testing compared to standard non-transgenic animals.

Assertion (A):
A probe is typically a single-stranded DNA or RNA molecule tagged with a radioactive substance.
Reason (R):
Probes are used in molecular diagnosis via autoradiography; if a patient's clone has a mutated gene, the probe will not hybridise, and the affected cells will not appear on the photographic film.

[Biotechnology-and-its-Applications] [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: The probe, tagged radioactively, is designed to be complementary to the normal nucleic acid sequence.
If the target gene is mutated, the probe cannot hybridise effectively, meaning the radioactive tag is not bound, and the corresponding area of the clone will not be detected by autoradiography (it won't appear on the film).

Assertion (A):
The protein encoded by the gene cryIAb controls the cotton bollworm.
Reason (R):
The specific choice of a Bt toxin gene for incorporation into a crop plant is crucial because most Bt toxins are highly insect-group specific.

[Biotechnology-and-its-Applications] [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 protein encoded by cryIAb controls the corn borer. The genes cryIAc and cryIIAb control cotton bollworms.
R is True: Bt toxins are insect-group specific (lepidopterans, coleopterans, or dipterans), making the choice of gene dependent on the target pest.