|
|
|
|
|
x
|
|
--»
|
|
|
P1
|
|
P2
|
|
F1
|
|
Yellow
|
|
green
|
|
all Yellow
|
|
-------------------------------------------
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
x
|
|
--»
|
|
|
F1
|
|
F1
|
|
|
|
|
|
|
|
|
|
|
|
|
|
F2
|
|
|
|
(F2)
Yellow : green = 3 : 1
|
|
--------------------------------------------
|
|
|
|
|
|
|
|
|
|
|
|
|
|
1/2 yellow
|
|
|
x
|
|
--»
|
|
|
F1
|
|
P2
|
|
|
|
|
|
|
|
|
|
|
|
|
1/2 green
|
|
-------------------------------------------
|
|
|
|
|
|
|
|
|
|
|
|
2/3
yellow
|
|
|
x
|
|
--»
|
|
|
F2
|
|
P2
|
|
|
|
|
|
|
|
|
|
|
|
|
1/3 green
|
|
-------------------------------------------
|
|
Let
'A' indicate the dominant
|
|
discrete
hereditary unit
|
|
responsible for
the phenotypic
|
|
expression of the
yellow colour in
|
|
pea seed.
|
|
Let 'a'
indicate the recessive
|
|
discrete
hereditary unit
|
|
responsible for
the phenotypic
|
|
expression of the
green colour in
|
|
pea seed.
|
|
Than obviously
the following
|
|
coupled
combinations are possible:
|
|
'AA'
(yellow), 'Aa' or 'aA' (yellow)
|
|
(and 'aA' = 'Aa')
and 'aa' (green).
|
|
So, if these
units are coupled the
|
|
crosses with
regard to these
|
|
phenotypic
aspects can be
|
|
expressed as:
|
|
|
|
P1
(AA -Yellow-) x
P2
(aa -green-)
|
|
--» F1
all (Aa -Yellow-)
|
|
|
|
F1
(Aa -Yellow-) x
F1 (Aa
-Yellow-)
|
--» 
F2 1 (AA
-Yellow-),
|
|
2 (Aa -Yellow-) &
|
|
1 (aa -green-)
|
|
|
|
And as was shown
earlier already
|
|
in the
experiments the ratio
|
|
Yellow : green =
3 : 1 indeed given
|
|
a necessarily
sufficient number of
|
|
F2
progeny to actualize fully the
|
|
developmental
possibilities.
|
|
|
