Q11 of 43 Page 1

A corn farmer has perennial problem of corn-borer infestation in his crop. Being environmentally conscious he does not want to spray insecticides. Suggest solution based on your knowledge of biotechnology. Write the steps to be carried out to achieve it.

• Bt toxin genes should be extracted from Bacillus thuringiensis.


• These genes are then to be incorporated into the corn.


• The toxin that will be encoded by the cry I Ab gene in corn will end of killing the pest without causing and harm to the environment.


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How is ‘somatic hybridization’ carried out? Mention one example of a somatic hybrid.

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How are DNA fragments visualised during gel-electrophoresis? What is elution?

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State ‘two’ observations made by German naturalist, Alexender von Humboldt during his extensive explorations in South American jungles.

OR


If in a population of size ‘N’ the birth rate is represented as ‘b’ and the death rate as ‘d’, the increase or decrease in ‘N’ during a unit time period ‘t’ will be:



The equation given above can also be represented as:



What does ‘r’ represent? Write any one significance of calculating ‘r’ for any population.


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When and where do tapetum and synergids develop in flowering plants? Mention their functions.

OR


Where are the following structures present in a male gametophyte of an angiosperm? Mention the function of each one of them.


(a) Germ pore


(b) Sporopollenin


(c) Generative cell