Applications Of Biotechnology

The Ti (tumor-inducing) plasmid is a large plasmid found in the bacterium Agrobacterium tumefaciens. This plasmid is responsible for transferring a segment of its DNA into plant cells, causing the formation of crown gall tumors. The Ti plasmid is widely utilized in plant genetic engineering to introduce new genes into plants.
Researchers exploit the Ti plasmid's natural ability to transfer DNA to manipulate plant genomes. By replacing the tumor-inducing genes with desired genes, scientists can create genetically modified plants with beneficial traits, such as pest resistance or increased yield.

Step 1: Understanding India's geographical area.

India has a total land area of approximately 3.28 million square kilometers, which constitutes about 2.4\% of the total geographical area of the world. The world's total land area is approximately 148.94 million square kilometers.

Step 2: Calculation of India's percentage.

The percentage of the world's area occupied by India is calculated as:

Step 3: Explanation of other options.

Option (A): Incorrect. 4.4\% is too high compared to India's actual land area proportion. Option (B): Incorrect. 6.1\% is significantly higher than the actual percentage. Option (D): Incorrect. 9.8\% is nearly four times India's actual proportion.

Step 4: Conclusion.

India occupies approximately 2.4\% of the world's total geographical area.

The correct Option is : 4

Step 1: Role of Agrobacterium in genetic engineering.
Agrobacterium tumefaciens is a bacterium that naturally transfers a part of its DNA (T-DNA) into plant cells. This mechanism is exploited in genetic engineering to introduce desired genes, such as those conferring herbicide resistance, into plants.

Step 2: Explanation of other techniques.
RNA interference (Option A): Used to silence specific genes but not for introducing herbicide resistance.

CRISPR-Cas9 gene editing (Option B): A precise genome editing tool but less commonly used for herbicide resistance compared to Agrobacterium-mediated methods.

Polymerase chain reaction (PCR) (Option C): Used for amplifying DNA sequences, not for transferring genes into plants.

The correct option is 3: EcoRI

EcoRI is a well-known restriction endonuclease that recognizes specific DNA sequences and cleaves the DNA at or near these sites. DNA polymerase and RNA polymerase are involved in DNA and RNA synthesis, respectively, while ligase is an enzyme that joins DNA fragments together.

The correct Option is : 2

Examine the role of cellophane tubes :
Structural support to dialysis machines: Cellophane tubes are not used for structural purposes.
Acting as semipermeable membranes: Historically, cellophane was utilized in hemodialysis machines for its semipermeable properties, allowing selective passage of substances like toxins and excess salts from the blood while retaining blood cells and essential proteins.
Delivering medication to patients: Cellophane tubes are not used for medication delivery.
Filtering blood cells directly: While cellophane membranes allow for filtration, their primary role was to act as semipermeable barriers rather than directly filtering blood cells.
Conclusion: The historical use of cellophane tubes in hemodialysis was primarily due to their semipermeable properties, enabling effective dialysis by filtering waste products from the blood.

Step 1: PCR amplification is an exponential process where the number of DNA copies doubles with each cycle.
Step 2: The formula to calculate the number of copies after cycles is:

Calculation:

Conclusion: After five cycles of PCR, DNA copies are produced.

Step 1: Historical background.
The concept of the "transforming principle" was first proposed by Frederick Griffith in 1928 during his experiments on \textit{Streptococcus pneumoniae}. He demonstrated that genetic material from heat-killed virulent bacteria could transform non-virulent bacteria into virulent ones. Step 2: Role of other scientists.

Oswald Avery: Later identified the transforming principle as DNA in 1944 through experiments with Avery, MacLeod, and McCarty.
James Watson: Contributed to the discovery of the structure of DNA alongside Francis Crick.
Rosalind Franklin: Provided critical X-ray diffraction data that aided in understanding the structure of DNA.

Step 3: Conclusion.
Frederick Griffith was the first to propose and demonstrate the existence of a transforming principle, though its identity as DNA was confirmed later by Avery and his colleagues. The correct answer is: Frederick Griffith.

The correct Option is : 2

Step 1: Understanding the PCR process.
Polymerase Chain Reaction (PCR) consists of three main steps:

Denaturation: DNA strands separate at high temperatures (90-98°C).

Annealing: Primers bind to the template DNA at moderate temperatures (40-60°C).

Extension: DNA polymerase synthesizes the new strand at 70-75°C.

Step 2: Annealing temperature.
During annealing, the temperature is optimized (40-60°C) to allow primers to hybridize with the template DNA without nonspecific binding.

Step 1: Understanding the role of cysteine in wool production.
Cysteine is a sulfur-containing amino acid crucial for forming disulfide bonds in keratin, which enhances the strength and quality of wool. Genes involved in the biosynthesis of cysteine are targeted for genetic modification.

Step 2: Key bacterial genes.
The bacterial genes and are responsible for the biosynthesis of cysteine. These genes are cloned and introduced into sheep to enhance wool quality and production.

Step 3: Explanation of other options.

Option (A): cys E, cys M. Correct. These are the genes involved in cysteine biosynthesis.

Option (B): cys F, cys G. Incorrect. These genes are not involved in cysteine biosynthesis.

Option (C): cys F, cys M. Incorrect. Only is relevant; is not involved.

Option (D): lac y, lac a. Incorrect. These are lactose metabolism genes and are unrelated to wool production.

Step 4: Conclusion.
The genes and are critical for improving wool quality.