Q15 of 27 Page 1

Compare and contrast the theories of evolution proposed by Darwin and Hugo De Vries.

Darwin based on his observations made during sea voyage round the world concluded that existing life forms share similarities not only among but also with life forms that existed years back. There had been a gradual evolution of life forms. Accordi �ng to Darwin, the fittest ones in an environment leave more progeny than others and hence survive more and get selected by nature. He called it natural selection and implied it as a mechanism of evolution.

Hugo deVries based on his work on evening primrose brought the idea of mutations- large difference arising in a population as the cause of evolution and not the minor variations (heritable) that Darwin talked about.



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The embryo sac in female gametophyte is seven-celled and eight nucleated structure. Justify the statement with the help of a labelled diagram.

OR


List the changes that occur when an ovule matures into the seed.

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Explain the different steps involved in the secondary treatment of sewage.

OR


Microbes can be used to decrease the use of chemical fertilizers. Explain how this can be accomplished.

 17

a) How do DNA fragments migrate and resolve in Gel electrophoresis?

b) How is lane one different from lane 2, 3 and 4 in the Gel electrophoresis set up?


c) How are pure DNA fragments made observable in the visible light?


dna.png