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Female fruit flies typically have two X chromosomes; male fruit flies typically

ID: 66038 • Letter: F

Question

Female fruit flies typically have two X chromosomes; male fruit flies typically have one X and one Y chromosome. They have other chromosomes too that are NOT sex chromosomes. Suppose there is a gene in fruit flies that influences the hairs a fly has on its thorax (the middle section of its body). A recessive allele of this gene causes the hairs to be very thick, while a dominant allele causes the hairs to be very thin. Suppose a heterozygous female and a thick-haired male have a large number of offspring, and half the offspring of both sexes have thin hairs. What do you know for sure about the location of this hypothetical gene?

Question 23 options:

It must be on an autosome (not a sex chromosome)

It could be on the X chromosome or the Y chromosome

It must be on the X chromosome

There is insufficient information to make any deduction about the gene's location

It must be on the Y chromosome

It must be on an autosome (not a sex chromosome)

It could be on the X chromosome or the Y chromosome

It must be on the X chromosome

There is insufficient information to make any deduction about the gene's location

It must be on the Y chromosome

Explanation / Answer

Answer: It must be on the X chromosome

It is due to X chromosome recessive inheritance.