Question

Given below are two statements: 

Statement I : Bt toxins are insect group specific and coded by a gene cry IAc. 

Statement II : Bt toxin exists as inactive protoxin in B. thuringiensis. However, after ingestion by the insect the inactive protoxin gets converted into active form due to acidic pH of the insect gut. 

In the light of the above statements, choose the correct answer from the options given below: 

(1) Both Statement I and Statement II are true 

(2) Both Statement I and Statement II are false 

(3) Statement I is true but Statement II is false 

(4) Statement I is false but Statement II is true

Answer 1

Correct option is (3) Statement I is true but Statement II is false 

As specific Bt toxin genes were isolated from Bacillus thuringiensis and incorporated into the several crop plants such as cotton. The choice of genes depends upon the crop and the targeted pest as most Bt toxins are insect-group specific. The toxin is coded by a gene named cry. There are a number of them, for example, the proteins encoded by the genes cry IAc and cry IIAb control the cotton bollworms, that of cry IAb controls corn borer.