Answer :

(a)

i)
• Can act as vector/can self-replicate to form multiple copies/ have selectable markers/ small in size will facilitate insertion / presence of ‘Ori’
• E. coli, Agrobacterium tumefaciens, Salmonella typhi, Bacteria.

ii)

• Ori’ – this is a sequence from where replication starts / any piece of DNA when linked to this sequence can be made to replicate with in the host cells controls copy numbe of linked DNA.

• Selectable marker helps in identifying and eliminating non transformants, and selectively permitting the growth of transformants during recombinant DNA technology.

iii) Restriction endonuclease identifies a specific palindromic sequence of DNA and cut the DNA at the specific sites in both the host as well in desired/foreign DNA, thereby creates “sticky ends” facilitating ligation to form a recombinant DNA.

or

(b)

i) Bt cotton crop is pest resistant/Insect resistant/ with increase productivity.

ii) Cotton bollworms/corn borer/tobacco budworm/army worm/ coleopterans (beetles)/dipterans (flies, mosquitoes).

iii) BT toxin protein exists as an inactive protoxin in the bacterium, but once the insect ingests this toxin it is converted into an active form, due to the alkaline pH of the gut, which solubilizes inactive crystals of toxic insecticide the activated toxin binds to the surface of the midgut epithelial cells of the insect, creates pores, that cause cell swelling and lysis and eventually the death of the insect.