Question

dihybrid crosses
in pea plants, the allele for tall (t) is dominant to the allele for short (t). the allele for green pods (g) is dominant to the allele for yellow pods (g).
1st plant\t2nd plant
homozygous tall, heterozygous green\theterozygous for both traits
what is its genotype?
what is its genotype?
offspring information
what % offspring will have green pods?\twhat % offspring will have yellow pods?\t%
what % will be tall with yellow pods?\t%\twhat % will be short with yellow pods?\t%
what fraction will be short with green pods?\twhat is the phenotypic ratio of this cross?
in mammoths, the allele for spotted skin (i) is dominant to the allele for non - spotted skin (i) and the allele for wooly hair (h) is dominant to the allele for non - woolly hair (h).
cross a mating pair of mammoths who are both heterozygous for both traits.
1st mammoth\t2nd mammoth
what is its genotype?\twhat is its genotype?
offspring information
what % chance for wooly, spotted?\t%\twhat % chance for non - woolly, spotted?\t%
what % chance for wooly, unspotted?\t%\twhat % chance for non - woolly, unspotted?\t%
what is the phenotypic ratio of this cross?\twhat is the genotype of a unspotted, non - woolly?

Explanation:

Step1: Determine pea - plant genotypes

The first plant is homozygous tall (TT) and heterozygous green (Gg), so its genotype is TTGg. The second plant is heterozygous for both traits, so its genotype is TtGg.

Step2: Set up Punnett - square for pea - plant cross

For the pod - color gene (Gg x Gg), the Punnett - square gives us the following genotypes: GG:Gg:gg = 1:2:1. So the percentage of green pods (GG + Gg) is 75% and yellow pods (gg) is 25%.
For the height and pod - color combination, we consider the cross of TtGg x TTGg. The probability of being tall (T_) is 100% since one parent is TT. The probability of yellow pods (gg) is 25%. So the percentage of tall with yellow pods is 100%×25% = 25%. The probability of being short (tt) is 0% since one parent is TT. So the percentage of short with yellow pods is 0%. The probability of being short (tt) is 0% and green pods (G_) is 75%, so the fraction of short with green pods is 0. The phenotypic ratio of the cross considering height and pod - color is 3 tall green : 1 tall yellow.

Step3: Determine mammoth genotypes

Both mammoths are heterozygous for both traits, so their genotype is IiHh.

Step4: Set up Punnett - square for mammoth cross

For the hair and skin - color cross IiHh x IiHh, the probability of woolly (H_) and spotted (I_) is $\frac{3}{4}\times\frac{3}{4}=\frac{9}{16}=56.25\%$. The probability of non - woolly (hh) and spotted (I_) is $\frac{1}{4}\times\frac{3}{4}=\frac{3}{16}=18.75\%$. The probability of woolly (H_) and unspotted (ii) is $\frac{3}{4}\times\frac{1}{4}=\frac{3}{16}=18.75\%$. The probability of non - woolly (hh) and unspotted (ii) is $\frac{1}{4}\times\frac{1}{4}=\frac{1}{16}=6.25\%$. The phenotypic ratio is 9 woolly spotted : 3 woolly unspotted : 3 non - woolly spotted : 1 non - woolly unspotted. The genotype of an unspotted, non - woolly mammoth is ii hh.

Answer:

Pea - plant 1 genotype: TTGg
Pea - plant 2 genotype: TtGg
% of offspring with green pods: 75%
% of offspring with yellow pods: 25%
% of tall with yellow pods: 25%
% of short with yellow pods: 0%
Fraction of short with green pods: 0
Phenotypic ratio of pea - plant cross: 3 tall green : 1 tall yellow
Mammoth 1 genotype: IiHh
Mammoth 2 genotype: IiHh
% chance for woolly, spotted: 56.25%
% chance for non - woolly, spotted: 18.75%
% chance for woolly, unspotted: 18.75%
% chance for non - woolly, unspotted: 6.25%
Phenotypic ratio of mammoth cross: 9 woolly spotted : 3 woolly unspotted : 3 non - woolly spotted : 1 non - woolly unspotted
Genotype of unspotted, non - woolly mammoth: ii hh