The image below depicts the result of gel electrophoresis.

If the ladder represents sequence length upto 3000 base pairs (bp),

a. Which of the bands (I - IV) correspond to 2500 bp and 100 bp respectively?

b. Explain the basis of this kind of separation and also mention the significance of this process.

Assertion ($\mathrm{A}$): All Eukaryotic cells have $\mathrm{RNAi}$ for cellular defence.

Reason ($\mathrm{R}$): $\mathrm{RNAi}$ silences $\mathrm{mRNA}$ and prevents translation.

Assertion (A): The fragments of DNA generated by the action of restriction endonucleases are separated by polyacrylamide gel electrophoresis.

Reason (R)： The separated DNA fragments are visualised as bright orange coloured bands after staining with Ethidium Bromide followed by exposure to $\mathrm{UV}$ - radiation.

Which of the following is true?

Study the following statement regarding rDNA technology and select the incorrect ones ?
(i) Taq polymerase extends the primers using the nucleotides provided in the reaction
(ii) Antibiotic resistance genes are considered as desirable genes in rDNA technology
(iii) DNA fragments are separated according to their charge only, in agarose gel electrophoresis
(iv) Transformation is a procedure through which a piece of DNA is introduced in a host bacterium
(v) To produce higher yields of a desired protein, host cells can be multiplied in a continuous culture
(vi) Downstream processing is one of the steps of PCR

Identify the labeled parts $1, 2, 3, 4$ in the given figure?

Identify the labels $\mathrm{M}$ and $\mathrm{N}$ in the following Agarose gel electrophoresis representation.