Q21 of 26 Page 1

(a) In pBR322, foreign DNA has to be introduced in tetR region. From the restriction enzymes given below, which one should be used and why:

PvuI, EcoRI, BamHI


(b) Give reasons, why the other two enzymes cannot be used.

(a) As is said in the question, foreign DNA has to be introduced in the tetracycline region of pBR322 cloning vector. This vector has two antibiotic resistance genes : ampicillin resistance gene and tetracycline resistance gene. These antibiotic resistance genes act as selectable markers. Tetracycline resistance gene include BamH1 and Sal1 restriction enzymes and Ampicillin resistance gene contains Pst1 and Pvu1 restriction enzymes. As the foreign DNA has to be introduced in the tetracycline resistance gene, BamH1 has to be used.

(b) The other two cannot be used as Pvu1 is the restriction enzyme of ampicillin resistance gene and EcoR1 does not belong to any resistance gene. When a foreign DNA is introduced at tetracycline region, it will first bind to BamH1 restriction enzyme. It alters the functioning of tetracycline resistance gene. The recombinants will grow in ampicillin containing medium but not on tetracycline containing medium which shows that the functioning of tetracycline has been silenced by the foreign DNA which wouldn’t be possible if Pvu1 and EcoR1 were used.


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Given below is the diagram of agarose gel kept under UV light:


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(b) What is the charge carried by DNA molecule and how does it help in its separation?


(c) How are the separated DNA fragments finally isolated?


OR


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(a) What is the resultant plant referred to as?


(b) Summarize the action of the gene introduced.

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The graph given below shows the distribution of biomes:


(a) What do the ‘X’ and ‘Y’ axes represent?


(b) Identify the ‘grassland’ and ‘coniferous forest’ biomes, from the above figure.


(c) Why is ‘F’ located at the given position in the graph?

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A son persuades his father to replace his old mobile phone with the latest model launched in the market. He also shares the latest features it has and explains how it can be of a help to him in the modern technological world. Father is reluctant in buying a new one and tries to explain about its environmental impact. How do you think, the biologist father has tried to convince his son? Justify the arguments of father and son both, by mentioning positive aspects of the behavior displayed by both of them in the situation concerned (three each).