A  monohybrid  cross between tall and
   dwarf  pea  plants.  A heritable characteristic, such as the height of
   the plant, is called a phenotype.

   The symbols D and d designate the tall and dwarf unit factors (genes),
   respectively,  in  the  genotypes  of  mature plants (sporophytes) and
   gametes.

   Sporophytes are shown in rectangles, and gametes are shown in circles.

   In  the  F[1]  generation,  all of the plants show just one of the two
   contrasting traits.

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