18. According to Mendel’s
second law, in the crossing
between homozygous
individuals concerning two
pairs of nonlinked alleles,
AABB x aaBB, what are the
genotypical and phenotypical
proportions in F1 and F2?

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Parental genotypes: AABB, aaBB.
from the parental generation:
and aB. Thus F1 present 100%
AaBb gametes ( the phenotypical
correspondent form).

F1 are AaBb individuals gametes
from their crossing be: AB, Ab, aB
ab. The casual combination these
gametes forms the genotypical
forms: one AABB, AABb, two AaBb,
four , one Aabb, oneAabb, one
, two aaBb and two . The
phenotypical proportion then be:
nine A_B_ (double ); three
A_bb (dominant for first pair,
recessive for second); three aaB_
(recessive the first pair, dominant
the second); one aabb (
recessive).