Q21 of 805 Page 1

Why do lepidoplerans die when they feed on Bt cotton plant ? Explain how does it happen.

Bt cotton plants are the transgenic plants that express a Bacillus thuringiensis genes called Cry gene.

Bacillus thuringiensis is a bacterium that produces proteins to kill certain insects such as lepidopterans(worm), coleopterans (beetles), and dipterans (flies/mosquitoes).


B.thuringiensis produces a protein crystal containing a toxin(inactivated state), when this inactivated toxin is ingested by the insect, it is converted into activated form due to alkaline pH of the gut. The alkaline pH of the gut results in the solubilisation of the crystal, thus converting it into the activated toxin.


Activated toxin binds to the epithelial cells of in the midgut of the insect and creates a pore that cause lysis and swelling and eventually death of the insect.


More from this chapter

All 805 →
19

Explain the role(s) of the following in Biotechnology:

(a) Restriction endonuclease


(b) Gel – electrophoresis


(c) Selectable markers in pBR322.


 20

Write the steps you would suggest to be undertaken to obtain a foreign-gene-product.

 22

in-situ’ conservation can help endangered/threatened species. Justify the statement.

OR


Name and describe any three causes of biodiversity losses.


 23

Public all over India is very much concerned about the deteriorating air quality in large parts of North India. Alarmed by this situation the Resident’s Welfare Association of your locality organized an awareness programme entitled “Bury not burn”. They invited you, being a biology student to participate.

(a) How would you justify your arguments that promote burying and discourage burning? (Give two reasons)


(b) With the help of flow charts, one for each practice depict the chain of events that follow.