In Bt cotton, the Bt toxin present in plant tissue as pro-toxin is converted into active toxin due to 

(1) Alkaline pH of the insect gut

(2) acidic pH of the insect gut

(3) action of gut microorganisms

(4) presence of conversion factors in insect gut

Some of the characteristics of Bt cotton are

(1) long fibre and resistance to aphids

(2) medium yields, long fibres and resistance to beetle pests

(3) high yield and production of toxic protein crystals which kill dipteran pests

(4) high yield and resistance to bollworms

The bacterium Bacillus thuringiensis is widely used in contemporary biology as a/an

(1) indicator of water pollution

(2) insecticide

(3) agent for production of dairy products

(4) source of industrial enzyme

What is true about Bt toxin?

1. The inactive protoxin gets converted into active form in the insect gut

2. Bt protein exists as active toxin in the Bacillus

3. The activated toxin enters the ovaries of the pest to sterilize it and thus prevent its

multiplication

4. The concerned Bacillus has antitoxins

Cry-I endotoxins obtained from Bacillus thuringiensis are effective against

(1) mosquitoes                         
(2) Nematodes
(3) boll worms                         
(4) Flies