necessity vs sufficiency 4 We have often discussed the conce

necessity vs. sufficiency

4. We have often discussed the concept of necessity vs. sufficiency as it applies to genetic analysis. Which of the following would demonstrate that the fruitless (fru) gene is necessary for male mating behavior in flies? a. mutation of the mouse fru homolog results in changes in mating behavior in mice b. ectopic expression of fru in female flies causes them to exhibit male mating behavior c. fru was cloned and shown to encode a transcription factor d. loss-of-function mutations in the fru gene cause abnormal or absent male mating behavior

Solution

The variabitily of the phenotype in women is due to X chomosome inactivation. The X chomosome inactivation occurs in females to compensate the lack of one X chomosome in males.