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Submitted by Anonymous

Teacher’s Note: Give the students a pedigree which will allow them to figure out the parental phenotypes. Any combination of alleles in the two parents may be used to create the pedigrees. In this way, different sections can have different puzzles-no copying from section to section!)

With a population of just under 100, dragons are now considered to be an endangered species. In an effort to both boost the population size and broaden the gene pool, a limited captive breeding program will be set up. Dr. Tracey obtains permission to harvest eggs and sperm from 2 individuals. These "captive breeding parents" are then released back into the wild. Unfortunately, a labeling error occurred in the lab and the parental phenotypes are lost.

Using the F1 offspring produced from the egg and sperm, determine the possible parental phenotypes.

Dragons have genes that are known to control the following morphological characteristics: presence of horns, the presence of wings, the number of legs and the ability to breathe fire.

The following are known alleles for the above dragon characteristics:

Horns: Horns are dominant over lack of horns.

Number of legs: The genes are expressed by the dragon having 4, 2, or 0 legs. This is because the leg alleles are incompletely dominant.

Fire Breathing: Green flame is dominant over red flame, and lack of fire breathing ability is dominant over red flame.

Wings: Double wing pairs are dominant over single wing pairs. Double wings are codominant with no wings. No wings is dominant over single wing pairs.

  1. Determine the phenotypes and genotypes for the parents using the provided pedigrees.
  2. In the F2 generation, some of the dragons have died mysteriously in certain breedings. Using the provided pedigrees, can you determine why mortality occurs? Explain how you can determine this and why or why not death occurs.

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