Answer and Explanation:
There are three phenotypes, so it seems that this an example of incomplete dominance, with the short tail being the intermediate form between long-tail and no-tail. Incomplete dominance is a condition where neither of the alleles completely dominates over the other one. Dominant alleles cannot completely cover up the recessive alleles. Descendents possess an intermediate phenotype between the two parental phenotypes and not the dominant one, which would appear if this would be the case of complete dominance.
<u>Available data:</u>
- Two short-tailed Manx cats are bred together.
- F1: 3 kittens with long tails, 5 short tails, and 2 without tails.
The T gene might express the tail trait. T allele expresses long the tail and is dominant over t allele which expresses the absence of the tail.
So, homozygous dominant individuals, TT, are long-tailed animals
homozygous recessive individuals, tt, have no tail
Heterozygous individuals, Tt, are short-tailed animals, the intermediate form.
Cross: Two short-tailed Manx cats are bred together
Parental) Tt x Tt
Gametes) T t T t
Punnet Square) T t
T TT Tt
t Tt tt
F1) 1/4 TT = Long-tailed animals
2/4=1/2 Tt = Short-tailed animals
1/4 tt = untailed animals
The ratio 3:5:2 of the progeny in the example is close enough to the Mendelian ratio 1:2:1.
