Monday, August 20, 2012

STPM Biology - chapter 16: Revision essay question 3

3. Do the results of test cross follow the Mendel’s Second Law? Explain your answer with a suitable example.

Answer



 No. An example is the test cross of Drosophilia flies which gives a ratio of 6:6:1:1 for the body colour and the size of wings. If the test cross follow Mendel’s Second Law, it will give a ratio of 1:1:1:1. The gene of the body colour and the size of wing are linked. When test cross occur, this result in the majority progeny of having the parental genotype and phenotype. Four types of progeny are produced. A small number of crossing over has occur resulting in new genetics combinations of linked gene in some gametes.


Assignment submitted by L.Y., Kong,  S. H., Lim, S. C., Soo, C. W. Tan and C.C.,Teh 2011/2012 (IBM)

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