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STD 12 - 10. biotechnology and its application — NEET STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceNEETSTD 12 - 10. biotechnology and its application4 Marks
MCQ
What is true about $Bt$ toxin?
  • A
    Bt protein exists as active toxin in theBacillus.
  • B
    The activated toxin enters the ovaries of the pest to sterilise it and thus prevent its multiplication.
  • C
    The concerned Bacillus has antitoxins.
  • ✓
    The inactive protoxin gets converted into active form in the insect gut.
✓

Answer

Correct option: D.
The inactive protoxin gets converted into active form in the insect gut.
d
(d) : Soil bacterium Bacillus thuringiensis produces proteins that kill certain insects like lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes). B.thuringiensis forms some protein crystals. These crystals contain a toxic insecticidal protein. This toxin does not kill the Bacillus (bacterium) because it exists as inactive protoxins in them. But, once an insect ingests it, it is converted into an active form of toxin due to the alkaline $pH$ of the alimentary canal. The activated toxin binds to the surface of midgut epithelial cells and create pores that cause swelling and lysis and finally cause death of the insect.

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