Question: 97. 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: Option (3)
Explanation:
Bt toxins produced by Bacillus thuringiensis are insect group specific.
They are coded by different cry genes, such as cry IAc, which is effective against specific insect pests.
Hence, Statement I is correct.
Bt toxin is present in B. thuringiensis as an inactive protoxin.
After ingestion by the insect, the protoxin is converted into its active form due to the alkaline pH of the insect gut, not acidic pH.
Therefore, Statement II is incorrect.
Thus, the correct answer is option (3).