Class 12 Zoology simulations · Biotechnology and its Applications

Bt cotton: how the Bt toxin works

Bollworm larvae feed on Bt and non-Bt cotton. In the alkaline gut the inactive protoxin becomes an active toxin.

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What to notice

The toxin does not harm the bacterium itself, because it is stored as an inactive protoxin.

Key relation

Inactive protoxin —alkaline gut pH→ active toxin → pores in midgut cells → death

Try this

Compare larva survival on Bt and non-Bt plants after a week.

What you can change

• Plant: choose Bt cotton (cry genes), Non-Bt cotton
• Days of feeding: 0 to 10 days
• Larvae on plant: 2 to 12

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