Question

Read the sources given and answer any four from the questions given below:

Bacillus thuringiensis (Bt), a soil bacterium, produces an insecticidal protein called Bt toxin. The Bt toxic gene from this bacteria is successfully transferred through genetic engineering to many plants like cotton plant. Cotton plant carrying Bt gene is called transgenic or Bt cotton. B. thuringiensis forms protein crystals which contain a toxin, the insecticidal protein called Bt toxin or Cry toxin. This Bt toxin protein exists in an inactive protoxin form in bacteria. The female of cotton bollworm is an orange-coloured moth that lays hundreds of eggs. The cotton bollworm larvae feed on the cotton bolls and cause extensive damage. When this inactive Bt toxin is ingested by the larvae of cotton bollworms, it is converted into an active form of toxin which binds to the epithelial cells of their midgut. The larvae stop feeding further and eventually die. The transgenic cotton plant, Bt cotton is resistant to bollworms. It reduces the need to spray insecticides for bollworms.

1. The Cry toxin is naturally present in
   1. Cotton plant
   2. Bacillus thuringiensis
   3. Bt cotton
   4. caterpillars
2. In Bt cotton, the Bt protein
   1. produces more cotton
   2. stops larva to feed further
   3. stops egg laying of adult
   4. increases protein content
3. The advantage of Bt cotton is that it
   1. contains active Bt toxin
   2. is transgenic
   3. is resistant to bollworms
   4. contains Bacillus thuringiensis
4. Which of the following statements is true for Bt toxin? Bt toxin is
   1. present as protoxin in Bacillus thuringiensis
   2. present in active form in bacteria
   3. converted to protoxin in larvae midgut
   4. harmful to Bacillus thuringiensis
5. Bt toxin is harmful to
   1. adult cotton bollworm
   2. Bt cotton
   3. Bacillus thuringiensis
   4. larvae of cotton bollworm

Answer 1

1. Bacillus thuringiensis
2. stops larva to feed further
3. is resistant to bollworms
4. present as protoxin in Bacillus thuringiensis
5. larvae of cotton bollworm