Why do toxic insecticide protein secreted by Bacillus thuringiensis kill insects?

In case of Bt cotton how does the toxic insecticide protein produced by bacterium kill the insect pest but not the cell Bacillus thuringiensis where the toxic protein is generated?

Mention the form in which inactive protein toxin is produced by Bacillus thuringiensis. How does it get activated in the pest body to kill it?

Explain why in case of Bt. insecticide protein produced by the bacterium kill the insect pest but not the cell of bacterium?

These questions consist two statements each, printed as Assertion and Reason. While answering these questions you are required to choose any one of the following four responses. If both Assertion and Reason are true and Reason is correct explanation of Assertion. If both Assertion and Reason are true but Reason is not correct explanation of Assertion. If Assertion is true but Reason is false. If both Assertion and Reason are false. Assertion:'Bt' toxin gene has been cloned from bacteria and expressed in plants to provide resistance from insect wihtout in need of insecticides. Reason: 'Bt' toxin is produced from bacterium Bacillus thuringiensis.

How is Bacillus Thuringiensis useful in biocontrol of insect pests ?

Why Bt toxin gene does not kill the Bacillus bacteria in which it is found ?

Insect tolerant gene from Bacillus thuringiensis is introduced using Ti plasmid of