Final Answer:
Some fruit flies have orange eyes and others have red eyes. If two orange-eyed fruit flies are crossed, their offspring always have orange eyes. If two red-eyed fruit flies are crossed, their offspring sometimes include both orange-eyed and red-eyed flies. c. The allele for red eyes is dominant. can be concluded from these observations.
Step-by-step explanation:
The observation that two orange-eyed fruit flies always produce orange-eyed offspring suggests that the trait for orange eyes is consistently expressed, indicating a dominant characteristic. On the other hand, the cross between two red-eyed fruit flies resulting in both red-eyed and orange-eyed offspring indicates that the red-eyed trait is not consistently expressed, suggesting it is recessive.
Therefore, the correct conclusion is that the allele for red eyes is dominant, making option c the most appropriate choice.
The pattern of inheritance observed aligns with Mendelian principles. When a dominant allele is present, its phenotype will be expressed in the offspring, masking the effect of the recessive allele
. In this case, the consistent expression of orange eyes in the presence of the red-eyed allele indicates that the red-eyed trait is recessive. Option a is incorrect, as a 1:1 ratio is not expected when crossing an orange-eyed fly with a red-eyed fly. Option b is also incorrect because the consistent expression of orange eyes indicates the dominance of the red-eyed allele.
c. The determination of dominance relationships is fundamental in understanding genetic inheritance. In this scenario, the observed patterns of eye color inheritance strongly suggest that the allele for red eyes is dominant to the allele for orange eyes, providing valuable insights into the genetic makeup of the fruit fly population.