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:
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:
- Both Statement I and Statement II are true
Both Statement I and Statement II are false
- Statement I is true but Statement II is false
Statement I is false but Statement II is true
The Correct Option is C
Solution and Explanation
Individual statement evaluations, with explanations rooted in biological principles, are provided to address the problem.
Statement I: "Bt toxins are insect group specific and coded by a gene cry IAc." This statement is accurate. Bacillus thuringiensis (Bt) synthesizes specific toxins, designated as Cry proteins, that target particular insect groups. The cry IAc gene is one of several cry genes encoding these toxins. These proteins exhibit high specificity towards insect orders, such as lepidopteran pests.
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." This statement is inaccurate. Although Bt toxin is indeed produced as an inactive protoxin by Bacillus thuringiensis, its activation is not triggered by the acidic pH of the insect gut. Rather, activation occurs under the alkaline conditions prevalent in the midgut of susceptible insects, where specialized gut proteases cleave the protoxin into its active state.
Based on these evaluations, the definitive conclusion is that Statement I is true, while Statement II is false.
Consequently, the applicable option is: Statement I is true but Statement II is false
