Applications Of Biotechnology

The correct answer is:

Option 3: Root

Explanation:

Meloidogyne incognita, commonly known as the root-knot nematode, primarily infects the roots of plants, including tobacco plants. This nematode causes the formation of galls (swelling) on the roots, which disrupts water and nutrient uptake, leading to stunted growth and reduced yields.

The nematodes enter the roots, causing damage that can make the plant more susceptible to other stresses.

Symptoms include root galls and overall poor plant health.

Therefore, root is the correct answer as it is the part of the tobacco plant infected by Meloidogyne incognita.

The correct answer is:

Option 1: Gene therapy

Explanation:

In 1990, a four-year-old girl with adenosine deaminase (ADA) deficiency was treated using gene therapy. ADA deficiency is a genetic disorder that affects the immune system, leading to severe combined immunodeficiency (SCID). The condition is caused by a mutation in the gene responsible for producing the ADA enzyme, which is crucial for the proper functioning of the immune system.

In this groundbreaking treatment, gene therapy was used to insert a healthy copy of the ADA gene into the patient's cells, providing them with the ability to produce the ADA enzyme. This marked one of the first successful uses of gene therapy in humans and opened the doors for further research and development in genetic treatments for inherited diseases.

Chemotherapy: This is a treatment for cancer and other diseases but was not the therapy used for ADA deficiency in this case.

Immunotherapy: This is used to treat cancer or to modulate the immune system, but it was not the primary treatment for ADA deficiency.

Radiation therapy: This is primarily used to treat cancer and was not relevant for this genetic disorder.

Therefore, gene therapy was the correct treatment option in this case.

Step 1: Understanding the function of the 'X' and 'Y' genes:

The E. coli plasmid pBR322 contains two important genes, labeled 'X' and 'Y', which play crucial roles in the replication and stability of the plasmid. These genes are vital in controlling the copy number and maintenance of the plasmid within bacterial cells.

Step 2: Role of gene 'X' (ori):

The 'X' gene in the diagram represents the origin of replication, denoted as ori. The origin of replication is a specific sequence where the replication process begins. It controls the copy number of the linked DNA, ensuring that the plasmid replicates efficiently within the bacterial cell.

Step 3: Role of gene 'Y' (rop):

The 'Y' gene corresponds to rop, which codes for a protein involved in plasmid replication. The rop protein helps in the stabilization of plasmid replication by regulating the number of plasmid copies. It plays a role in the maintenance of the plasmid during cell division.

Step 4: Conclusion:

Therefore, in the given diagram:

• 'X' is ori: The origin of replication, controlling the copy number of linked DNA.
• 'Y' is rop: A gene coding for a protein involved in plasmid replication.

Incorrect Options: Options (1), (3), and (4) are incorrect because the roles assigned to 'X' and 'Y' in these options do not correspond to the functions of the origin of replication (ori) and the rop gene.

Answer: The correct answer is Option 1.

Step 1: What is Totipotency?

Totipotency refers to the ability of a single plant cell to develop into a whole plant. This property is unique to certain plant cells and allows for plant regeneration through methods like tissue culture.

Step 2: How Totipotent Cells Work

In totipotent cells, all genetic information required for the development of the entire plant is retained. This allows these cells to differentiate into all types of plant tissues, leading to the formation of a complete plant.

Conclusion

Thus, the ability to generate a whole plant from a single cell is called totipotency.