Law of independent assortment.
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   The  P  plants  of  this  dihybrid  cross  are true-breeding: one with
   yellow-round seeds and the other with green-wrinkled seeds.
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   The F[1] dihybrids are heterozygous for both characters.
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   Self-pollination  of  the F[1] yields a phenotypic ratio of 9:3:3:1 in
   the F[2], NOT the 3:1 typical of a monohybrid cross.
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   This  id  due  to  the  independent  assortment of the 2 traits during
   meiosis, assuming they are on different chromosomes.
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   One  way to ensure you have all combinations of gametes for a dihybrid
   cross is the <A ClAsS=MIZ Href="../../..//med/foil.html" oNClick="popurlts('../../..//med/foil.html',395,201);txtcolor('assortment1','gray');return false;" Id=assortment1 ClAsS=MIZ>FOIL</A> method.
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