Question

Identify the incorrect statements.
(A) Bacillus thuringiensis is a transgenic organism.
(B) Bt toxin enters the testes or the ovaries of the insect pest, sterilizes it, and thus prevents its multiplication.
(C) Proteins encoded by cryIAc and cryIIAb control cotton bollworms.
(D) Bt protein exists as an active toxin in Bacillus.
(E) Alkaline pH of the insect gut solubilizes the toxin protein crystals.
Choose the correct answer from the options given below:

• A. (A), (B), and (D) only
• B. (B) and (D) only
• C. (C) and (D) only
• D. (C), (D), and (E) only

Answer 1

The Correct Option is B

Let's evaluate each statement regarding Bacillus thuringiensis (Bt):

(A) Bacillus thuringiensis is a transgenic organism: This statement is incorrect. Bacillus thuringiensis (Bt) is not a transgenic organism by itself. It is a naturally occurring bacterium that produces Bt toxin (Cry proteins). However, Bt genes have been incorporated into transgenic plants like Bt cotton, making them capable of producing the toxin. So, while Bt is not itself transgenic, it can be used in transgenic crops.

(B) Bt toxin enters the testes or the ovaries of the insect pest, sterilizes it, and thus prevents its multiplication: This statement is incorrect. Bt toxin does not work by sterilizing the pest. Instead, it kills the insect larvae by damaging their gut cells when ingested. The idea that it enters the testes or ovaries and sterilizes the insect is not accurate.

(C) Proteins encoded by cryIAc and cryIIAb control cotton bollworms: This statement is correct. The proteins CryIAc and CryIIAb produced by Bt are toxic to specific pests like cotton bollworms.

(D) Bt protein exists as an active toxin in Bacillus: This statement is incorrect. Bt toxin exists as inactive protein crystals in Bacillus thuringiensis. The toxin becomes active only when it is ingested by the insect, and the alkaline pH of the insect’s gut solubilizes the toxin, activating it.

(E) Alkaline pH of the insect gut solubilizes the toxin protein crystals: This statement is correct. The alkaline pH in the insect's gut helps solubilize the Bt toxin crystals, making the toxin active, which then binds to the gut cells and disrupts their function, leading to the insect's death.

Thus, the incorrect statements are (B) and (D).

The correct answer is (2) (B) and (D) only.

Answer 2

Statements (B) and (D) are incorrect: (B) Bt toxin does not target reproductive organs but affects the insect gut; (D) Bt protein exists as an inactive protoxin, which is activated in the insect's alkaline gut. Bt protein's effectiveness lies in its specific activation in pest guts, not general toxicity.