Bacillus thuringiensis is a bacterium that parasitises the caterpillars of some harmful moths (e.g. gypsy moths). The bacteria kill by a toxin which they secrete. The gene for this toxin has been introduced into some crop plants in an effort to protect them from attack by gypsy moths without spraying. Transgenic cotton plants that express the gene for the Bt toxin are resistant to gypsy moth infestations.


(a) Explain the possible advantages and disadvantages of introducing what is effectively an insecticide producing gene into plants.