In poultry, the genes for rose comb (R) and pea comb
(P) produce walnut whenever they occur together
(R__ P__); single-combed individuals have the
homozygous condition for both genes (rr pp).
(a) Give the F1 and F2 phenotypic results of a
cross of a pure-breeding rose comb (RR pp)
with a pure-breeding pea comb (rr PP).
(b) Give the phenotypic results of a cross of Rr Pp
x rr Pp.
(c) Give the phenotypic results of a cross of RR
Pp x rr Pp.
(d) Give the phenotypic results of a cross of Rr pp
x rr Pp.
(e) Give the phenotypic results of a cross of Rr Pp
x rr pp. What will be an ideal response?
Question 2In the late 1920s, a mutation occurred in many silver
fox farms around the world. The fox farms that sold
expensive furs were proud of the quality of their furs,
and each advertised that it had the best, purest breed
of all the fox farms. The new mutations produced a
platinum coat pattern that was commercially
desirable, so the farms crossed them to get more. The
results of their breeding experiments were as
follows: (1) silver x silver >>> all silver offspring;
(2) silver x platinum >>> equal numbers of silver
and platinum; (3) platinum x platinum >>> two
platinum for each silver offspring. Explain. What will be an ideal response?
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