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प्रश्न
In view of the current food crisis, it is said, that we need another green revolution. Highlight the major limitations of the earlier green revolution.
उत्तर
Limitations of the green revolution:
- The Green Revolution succeeded in tripling the food supply but yet it was not enough to feed the growing human population. Increased yields have partly been due to the use of improved crop varieties, but mainly due to the use of better management practices and use of agrochemicals (fertilisers and pesticides). However, for farmers in the developing world, agrochemicals are often too expensive, and further increases in yield with existing varieties are not possible using conventional breeding.
- Use of agrochemicals causes eutrophication in aquatic ecosystems and biomagnification in terrestrial ecosystems.
- Water logging and soil salinity are some of the problems that have come in the wake of green revolution.
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संबंधित प्रश्न
Answer the following question.
List one advantage and one disadvantage of an apomictic crop.
GM crops especially Bt crops are known to have higher resistance to pest attacks. To substantiate this an experimental study was conducted in 4 different farmlands growing Bt and non Bt-Cotton crops. The farm lands had the same dimensions, fertility and were under similar climatic conditions. The histogram below shows the usage of pesticides on Bt crops and non-Bt crops in these farm lands.
- Which of the above 4 farm lands has successfully applied the concepts of Biotechnology to show better management practices and use of agrochemicals? If you had to cultivate, which crop would you prefer (Bt or Non- Bt) and why?
- Cotton Bollworms were introduced in another experimental study on the above farm lands wherein no pesticide was used. Explain what effect would a Bt and Non Bt crop have on the pest.
Cry-genes have been introduced in:
A cell swells up when kept in:
Assertion (A): In Bt cotton, B. thuringiensis produces a toxic insecticidal crystalline protein which destroys bollworms.
Reason (R): B. thuringiensis produces this toxic protein in an inactive form, but when an insect ingests this inactive protein, it is converted into active form of toxin due to the alkaline pH of gut which solubilises the crystals, which is responsible for the death of bollworm.
Discuss the advantages of GMO.
Insects in the Lepidopteran group lay eggs on maize crops. The larvae on hatching feed on maize leaf and tender cob. In order to arrest the spread of three such Lepidopteran pests, Bt maize crops were introduced in an experimental field.
A study was carried out to see which of the three species of lepidopteran pests was most susceptible to Bt genes and its product.
The lepidopteran pests were allowed to feed on the same Bt-maize crops grown on 5 fields (A-E).
The graph below shows the leaf area damaged by these three pests after feeding on maize leaves for five days.
Key for lepidopteran insect pest species
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Species I |
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Species II |
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Species III |
Insect gut pH was recorded as 10, 8 and 6 respectively for Species I, II and III respectively.
(a) Evaluate the efficacy of the Bt crop on the feeding habits of the three species of stem borer and suggest which species is least susceptible to Bt toxin.
(b) Which species is most susceptible to Bt-maize, and explain why?
(c) Using the given information, suggest why a similar effect was not seen in the three insect species.
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RNA interference (RNAi) holds great potential as a therapeutic agent for the treatment of human diseases and as biocontrol agents in controlling pests in the field agriculture. An experiment was carried to study the use of 'RNAi' for the potential treatment of disorders of cholesterol metabolism. Some people possess genetic mutations with elevated levels of ApoB gene which predisposes them to coronary artery diseases. Lowering the amount ApoB can reduce the number of lipoproteins and lower the blood cholesterol. Tracy Zimmerman and her colleagues used RNAi in 2006 to reduce the level of ApoB in non human primates Cynomolgus monkeys. One group of monkeys were given RNAi treatment (small interfering RNAs, SiRNAs) (doses 1 mg/kg, SiRNAs), second group of monkeys were given RNAi treatment (doses 2.5 mg/kg, SiRNAs) and third group of monkeys were injected with saline. |
The results of the study are depicted in the graph below:
- How does the treatment with 2.5 mg/kg bring an effect on cholesterol metabolism when compared from 24 hours and 144 hours?
- Write any two natural sources from where dsRNA molecule could be obtained for silencing the specific mRNA.
- How is RNAi used in controlling the infection on the roots of tobacco plants by the nematode Meloidogyne incognitia?
The main objective of the production of pest-resistant GM crops is to ______.
How has man exploited cry proteins to his benefit?
