Practice free Zoology NEET multiple-choice questions online with instant answers and detailed explanations. No login required.
The inactive protoxin form of Bt toxin needs to be converted into an active form due to what specific characteristic of the insect gut environment?
The text clearly states, 'once an insect ingest the inactive toxin, it is converted into an active form of toxin due to the alkaline pH of the gut which solubilise the crystals.'
Which of the following is a direct consequence of the activated Bt toxin binding to insect midgut epithelial cells?
The text explains, 'The activated toxin binds to the surface of midgut epithelial cells and create pores that cause cell swelling and lysis and eventually cause death of the insect.'
The gene cryIAb is known to control which specific pest?
The text explicitly states, 'the proteins encoded by the genes cryIAc and cryIIAb control the cotton bollworms, that of cryIAb controls corn borer.'
Which method involves spraying dried spores of Bacillus thuringiensis mixed with water onto plants to control butterfly caterpillars?
The text mentions Bacillus thuringiensis as a 'microbial biocontrol agents that can be introduced in order to control butterfly caterpillars' and describes the process of spraying dried spores.
The use of Bt toxin genes in plants is an example of creating a bio-pesticide. This approach aims to reduce reliance on which of the following?
The text states, 'Bt toxin gene has been cloned from the bacteria and been expressed in plants to provide resistance to insects without the need for insecticides; in effect created a bio-pesticide.'
Why does Bacillus thuringiensis not get killed by its own toxin?
The text asks, 'Why does this toxin not kill the Bacillus?' and answers, 'Actually, the Bt toxin protein exist as inactive protoxins...'
Which of the following is NOT an example of a crop plant that has been genetically modified to express Bt toxin genes?
The text lists 'Bt cotton, Bt corn, rice, tomato, potato and soyabean' as examples. Bt wheat is not mentioned.
The specific Bt toxin genes chosen for incorporation into crop plants depend upon:
The text states, 'The choice of genes depends upon the crop and the targeted pest, as most Bt toxins are insect-group specific.'
What happens to the protein crystals formed by B. thuringiensis during a particular phase of its growth?
The text mentions, 'B. thuringiensis forms protein crystals during a particular phase of their growth. These crystals contain a toxic insecticidal protein.'
Genetic modification of plants has led to 'pest-resistant crops'. This is considered a benefit because it:
The text states that genetic modification has '(ii) reduced reliance on chemical pesticides (pest-resistant crops).' While GM crops can tolerate abiotic stresses, reducing pesticide use is the specific benefit related to pest resistance.
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