(a) Plant in which CryIAb has been introduced to prevent infestation by corn borer is Bt corn. Such plants are known as transgenic plants.

(b) CryIAb gene isolated from Bacillus thuringiensis forms protein crystals. The crystals contain toxic insecticidal protein, which does not kill the bacterium but is toxic for insects. The Bt toxin proteins exits as inactive protoxin but once an insect ingests the inactive toxin it is converted into an active form of toxin due to the alkaline pH of the alimentary canal that solubilises the crystals. The activated toxin binds to the surface of midgut epithelial cells and create pores which cause cell swelling and lysis and finally cause death of the insect.