Q19 of 51 Page 1

A. How do organic farmers control pests? Give two examples.

B. State the difference in their approach from that of conventional pest control methods.

A. Organic farmers control pests either by natural predation or by using biological control.


Examples:


I. Owls are used to kill rats in the crop field, lady bird used to kill aphids.


II. Bt Cotton plants are introduced with the Bt toxin gene of the bacterium Bacillus thruingiensis. This gene provides the cotton crops resistance against the bollworms.


B. Differences:



More from this chapter

All 51 →
13

A. How does a farmer use the dormancy of seeds to his advantage?

B. What advantages a seed provides to a plant?

 17

Predation is usually referred to as a detrimental association. State any three positive roles that a predator plays in an ecosystem.

 20

A. Why must a cell be made ‘competent’ in biotechnology experiments? How does calcium ion help in doing so?

B. State the role of ‘biolistic gun’ in biotechnology experiments.

 25

Give a genetic explanation for the following cross. When a tall pea plant with round seeds was crossed with a dwarf pea plant with wrinkled seeds then all the individual of F1-populations was tall with round seeds. However selfing among F1-population led to a 9: 3 3 : 1 phenotypic ratio.