question_answer 21)

  The trigger for activation of toxin of Bacillus thuringiensis is (a) acidic pH of stomach                                                                (b) high temperature (c) alkaline pH of gut                                                       (d) mechanical action in the insect gut

Answer:

                  (c)Bt toxins are initially inactive protoxins but after ingestion by the insect these inactive toxin becomes active due to the alkaline pH of the gut which solublise the crystals. Hence, high pH value is required to make Bt toxins active. Under high temperature and acidic pH, Bt toxins remain insoluble and inactive.