Step 1: Understanding genetically modified (GM) plants.
Genetically modified plants are those in which specific genes have been inserted to improve traits such as pest resistance, disease resistance, or nutritional quality. One common modification is the introduction of the Bacillus thuringiensis (Bt) gene, which produces a toxin harmful to insects but safe for humans.
Step 2: Analysis of options.
- (A) BT maize: This is a genetically modified maize that contains the Bt gene for insect resistance.
- (B) BT cotton: One of the most widely used GM crops, Bt cotton resists bollworm pests.
- (C) BT rice: Research has developed Bt rice for resistance against stem borers.
- (D) All of these: Since all the above-mentioned plants are genetically modified, this is correct.
Step 3: Conclusion.
The correct answer is (D) All of these, because Bt maize, Bt cotton, and Bt rice are all genetically modified plants.
Answer the following questions:
(a) [(i)] Explain how some strains of Bacillus thuringiensis produce proteins that kill certain insects such as lepidopterans but do not kill the Bacillus.
[(ii)] How is the above mechanism exploited for the production of Bt cotton plant by biotechnologists?
(b) [(i)] Explain how the amplification of gene of interest is done using PCR.
[(ii)] State two applications of the desired amplified fragment of DNA.
The basic scheme of the essential steps involved in the process of recombinant DNA technology is summarised below in the form of a flow diagram. Study the given flow diagram and answer the questions that follow.
(a) What is the technical term used for Step 4 in the above process?
(b) Which of the given two combinations of restriction enzyme should be used in Step 1? Justify your answer.
(i) EcoR I to cut the plasmid and Hind III to cut the alien DNA.
(ii) EcoR I to cut both the plasmid and alien DNA.