The scenario is imaginary.
A blue alien and a green alien mate and produce 1,000 offspring that are all blue. Another alien couple who share the same genotyope and phenotype as the first couple also mate and produce 1,000 offspring, all of which are blue. Males and females from the two matings then mate with one another. Matings between the blue offspring produce 75% blue and 25% green offspring.
What type of inheritance is shown?
Incomplete dominance
or
co-dominance
or
Complete dominance
BBxgg=Bg,Bg,Bg,Bg first generation
BgxBg=BB,Bg,Bg,gg second generations
Complete dominance is a form of dominance in heterozygous condition wherein the allele that is regarded as dominant completely masks the effect of the allele that is recessive. For instance, an individual carrying two alleles that are both dominant (e.g. AA), the trait that they represent will be expressed.
The type of inheritance shown in this scenario is complete dominance.
To understand why, let's break down the options and how they relate to this situation:
1. Incomplete dominance: In incomplete dominance, the offspring would exhibit a blend or intermediate phenotype of the two parents. For example, if the blue color was dominant and the green color was recessive, the offspring would have a phenotypic expression that is a mix of blue and green. However, in the given scenario, all 1,000 offspring from both matings are blue, indicating that there is no blending or intermediate phenotype observed. Therefore, incomplete dominance is not applicable here.
2. Co-dominance: Co-dominance occurs when both alleles of a gene are expressed fully and equally in the phenotype of an individual. In the case of color, this would mean that both blue and green colors would be expressed simultaneously without blending. However, since all 1,000 offspring from both matings are blue, it indicates that the blue color is completely dominant over green, suggesting that co-dominance is not observed in this scenario.
3. Complete dominance: In complete dominance, one allele is expressed completely, while the other allele is entirely masked or recessive. In this case, the blue color allele is fully expressed, and the green color allele is completely masked, resulting in all the offspring being blue. This matches the observed results of the scenario, where 100% of the offspring are blue. Hence, the inheritance pattern observed in this scenario is complete dominance.
In summary, complete dominance is the type of inheritance shown in this imaginary scenario.