Genetics Help.

Jon DiVita hurbie at
Sun Sep 14 17:09:32 EST 1997

	Hello, I have acouple questions that I could use some help on.

Hello.  I'm a student at a University in the United States.  I
had a genetics exam and wanted to check my answers with a
Here's my question:
		Aleurone color gene R, where R is necessary for color
within the
aleurone.  Pigment P, where P is necessary for purple aleurone color. 
Endoderm gene Y, where Y is necessary for yellow colored endoderm.
		Seeds of the following colors were gron up and
P1: Red seed crossed with a White seed.
F1: Red seeds, Yellow seeds, Purple seeds.

pp-causes red seeds PP-purple seeds YY-Yellow endosperm yy-white
RR colored aleurone Rr-Colored aleurone rr-clear aleurone.

a) What is the genotype of the P1 white seeds?

b) WHat are the genotypes of the: F1 red seeds, F1 yellow, and

c) What is the expected proportion of the F1 red to yellow seeds?

	A pregnant female mouse was discovered in which the coat was
two-toned (calico-like)  with patches of black hairs and patches of
yellow hairs.
	This two-toned mouse was sickly but gave birth to a single
litter of offsprings (F1) before expiring.
		F1: 5 black males
		      5 black females
		     4 two-toned sickly females of which dies at

(Define your gene/allele nomenclature)

a: What class of offspring is missing?
b) Based on the phenotype of the F1 progeny, what was the genotype of
the P1 father?
c) What was the genotype of the original P1 female?
d) Explain why one class of offspring is missing?

Thanks for your help.

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