Q4. Why does NCERT call chemical pesticides harmful?
They are toxic and extremely harmful to human beings and animals alike, and they have polluted our soil, ground water, fruits, vegetables and crop plants (NCERT page 156).
Q5. What does it mean that the organic farmer’s approach is holistic?
Instead of killing useful and harmful life forms indiscriminately with chemicals, it seeks to understand the webs of interaction between the many organisms of the field, predators as well as pests (NCERT pages 156–157).
Q6. Where is the Bt toxin released, and what happens to the caterpillar?
In the gut of the larvae: there the toxin is released and the larvae get killed (NCERT page 157).
Q7. How has genetic engineering used Bacillus thuringiensis?
Its toxin genes have been introduced into plants, which become resistant to attack by insect pests; Bt-cotton is an example grown in some states of India (NCERT page 157).
Q8. When are baculoviruses especially useful?
When beneficial insects are being conserved as part of an integrated pest management (IPM) programme, or when an ecologically sensitive area is being treated, because they are species-specific and narrow-spectrum (NCERT page 157).