13.1 A
2. F x F à FF
F x f à Ff
f x f à ff
3. genotype of his gamete = F
her genotype = ff
her gametes carry f
childs genotype = Ff
childs phenotype = dominant (free earlobe)
4. a) AA = purple
Aa = purple
aa = white
b) white flower = aa
c) gametes of purple flower = A
d) genotypes of cross = heterozygous or Aa
e) Phenotype of cross = dominant or Purple
f) Punnett square
a a
A Aa Aa
A Aa Aa
g) Punnett square
a a
A Aa Aa
a aa aa
Possible genotypes = Aa, aa
Possible phenotypes = Purple, white, or dominant, recessive
i) 2/4 or 0.5
13.1 B
1. closest ratio = 3:1
2 a) PP, Pp
b) P
c) pp
d) do a test cross. Pp x P? the resulting offspring will tell you the genotype.
If all offspring show dominant trait, then unknown parent = PP
If offspring are 1 dominant: 1 recessive, then unknown parent = pp
13. 2 Dihybrid Inheritance
1a) PPDD, PPDd, PpDD, PpDd
1b) PPdd, Ppdd
1c) ppDD, ppDd
1d) ppdd
2a) PpDd
2b) PD, Pd, pD, pd
2c)
cross = PpDd x PpDd
PD Pd pD pd
PD PPDD PPDd PpDD PpDd
Pd PPDd PPdd PpDd Ppdd
pD PpDD PpDd ppDD ppDd
pd PpDd Ppdd ppDd ppdd
2d) PPDD, PPDd, etc….
ratio of genotypes = “don’t worry about”
ratio of phenotypes = 9:3:3;1 (Dom-Dom, Dom-Rec, Rec-Dom, Rec-Rec)
2e) ppDD = 1/16 or 0.0625
PpDd = 4/16 or 0.25
PPDd = 2/16 or 0.125
2f) 1/16 x 1/16 x 1/16 = 1/4096 or 0.00024
9/16 x 9/16 x 9/16 = 729/4096 or 0.178
2g) PpDd
phenotype = dominant for both traits or Pigmented eyes and Dimpled chin.
13.2 B An observable dihybrid cross
1) Both parents = PpSs
2) see 2c) above. Predicted ratio = 9:3:3:1
3) Purple and smooth seem dominant
Yellow and wrinkled seem recessive
5) You do not need to complete the ChiSquare test.
Pre-Lab questions
1 a
2 b
3 d
4 a
5 d
6 d
7 d
8 a
9 d
10 a