申論題

2. A mating of one strain of pure-breeding yellow mice with pure-breeding brown mice resulted in black hybrids. A cross between the black Fs hybrids produces 42 black, 18 brown, and 20 yellow offspring, At least two different models of genetic constitution conform to the observed data. (a) Please describe these models of genetic constitution and use the Chi-square test for goodness-of-fit to evaluate how the model conforms to observed results. (10 points) (b) In order to validate which model is correct, please design a crossing scheme and explain how the expected phenotypes of progenies in this cross are able to distinguish the aforementioned models. The two parents of this crossing scheme must come from the existed mice. (10 points)