Question

Question 7:

A P X P cross between a vertically-striped purebred fly with a horizontally-striped purebred fly yields the following results:

F1 Observed Results:

1000 black F1 flies

F2 Observed Results:

250 vertically-striped flies

500 black flies

250 horizontally-striped flies

Part 1: Predict the phenotypic ratio of the offspring of an F1 X F1 cross.

The F1 X F1 cross yields:

Part 2: How do these results compare with your predicted results?

Part 3: Describe this pattern of inheritance. (Hint: make sure your answer includes a specific name for this variation from the typical dominant-recessive Mendelian mode of inheritance.)

Part 4: Summarize the similarities and differences between the two variations to dominance. (Hint: make sure your answer includes a specific names for these variations, first using butterflies and second using fly abdomens, from the typical dominant-recessive Mendelian mode of inheritance.)

Answer 1

1. Phenotypic ratio of of the offspring of an F1 X F1 cross is 3:1 according to Mendel's experiment.

The F1 X F1 cross yields 1:2:1 phenotypic ratio.

2. The pattern of inheritance is co-dominance. The phenotype of all the F1 progeny should be according to any of the parental class (here which parental class is dominant, not mentioned). But all of the F1 projeny are intermediate.

3. Dominant alleles are expressed over recessive one. In co-dominance both of the alleles are dominant simultaneously.