Q168 / 180 · AIIMS 2014 · Zoology

What is true about Bt toxin?

  • A
    Bt protein exists as active toxin in the Bacillus.
  • B
    The activated toxin enters the ovaries of the pest to sterilise it and thus prevent its multiplication.
  • C
    The concerned Bacillus has antitoxins.
  • Correct answer
    D
    The inactive protoxin gets converted into active form in the insect gut

Solution

Some strains of Bacillus thuringiensis produce proteins that kill certain insects like lepidopterans and coleopterans, etc. Bacillus thuringiensis forms some protein crystals. These crystals contain a toxic insecticidal protein. Bt toxin proteins exist as inactive protoxins, but once an insect ingests the inactive toxin it is converted to active form of toxin due to the alkaline $\mathrm{pH}$ of the alimentary canal that solublizes the crystals.

Hence, the correct answer is option: 'D'.

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