Biology Sample Question Paper Sheet - Class Xii, Central Board Of Secondary Education, 2010 Page 7
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39(d)
Define elution.
27. Explain with reference to PCR
(a)
A specific enzyme helps in amplication in PCR. Name the bacterium from which it is isolated
and state how its thermostable nature is helpful.
(b)
Explain its use in molecular diagnosis.
Section - D
28. A woman has conceived and implantation has occured in her uterus. Explain the sequence of changes
upto parturition which take place within her body.
OR
“ Incompatibility is a natural barrier in the fusion of gametes”. Justify the statement.
29. (a)
Give reasons for -
(i)
Both strands of DNA are not copied during transcription.
(ii)
Transcription and translation in bacteria can be coupled.
(b)
Differentiate between the process of transcription in prokaryotes and eukaryotes.
OR
Stanley Miller performed an experiment by recreating in the lab the probable conditions of the
atmosphere of the primitive earth.
(i)
What was the purpose of the experiment ?
(ii)
In what form was the energy supplied for the chemical reaction to occur?
(iii)
What is biogenesis?
(iv) Give a diagrammatic representation of Miller’s experiment.
30. (a)
On seeing the bad state of roads in your locality, as a student, you have recommended to the
Municipal Corporation to use polyblend.
(i)
What is polyblend? Point out its raw material?
(ii)
How will it be advantageous?
(b)
What are e-wastes? Explain the method of their disposal.
OR
(a)
What is meant by ecological succession? How does it occur? Explain.
(b)
Differentiate between Primary and Secondary succession.
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