1. How many unique gametes can organisms with each of the following genotypes produce?
RrBb, RRbb, RrBB, rrbb, AaBbRr, AabbRr AABBRrDD
2. In genetics experiments with garden peas, a plant with purple flowers and smooth pods is crossed with a plant that has white flowers and constricted pods. All of the offspring of this cross have purple flowers and smooth pods.
a. What does this tell you about the purple/smooth alleles?
b. What were the genotypes of your original plants?
c. What are the genotypes of the offspring of this cross (F1)?
d. What genotypes are possible in the gametes produced by the F1?
e. What phenotypic ratio would you expect for the F2 generation? Draw a Punnett square to support your answer.
3. If, for a particular species of plant, blue flowers are dominant over white, and multiple petals are dominant over single petals, give the expected genotypic and phenotypic ratio of the following crosses:
a. white multiple (homozygous) x blue (heterozygous) single
b. white single x blue (homozygous) multiple (heterozygous)
c. white single x white single
4. What is the probability that each of the following pairs of parents will produce the indicated offspring (assuming independent assortment of all gene pairs)?
a. AA x aa ---> Aa
b. Aa x aa ---> Aa
c. AaBb x aabb ---> AaBb
d. AABBCC x aabbcc ---> AaBbCc
e. AABbCc x AaBbCc ---> AABbCC
f. AaBbCc x AaBbCc ---> AaBbCc
g. aaBbCC x AABbcc ---> AaBbCc
5. In dogs, dark coat color is dominant over albino, and short hair is dominant over long hair. If these effects are caused by two independently segregating genes, write the most probable genotypes for the parents of each of the following crosses, using the symbol C and c for coat-color alleles and H and h for short and long hair alleles.
Phenotypes of offspring
Parental Phenotypes Dark Short Dark Long Albino Short Albino Long
a) dark short x dark short 89 31 29 11
b) dark short x dark long 18 19 0 0
c) dark short x albino short 20 0 21 0
d) albino short x albino short 0 0 28 9
e) dark long x dark long 0 32 0 10
f) dark short x dark short 46 16 0 0