You are a graduate student in the lab of a famous fly geneticist. You need to analyze a batch of mutant flies that were recently created in her laboratory to identify the single gene that is most likely mutated in each of the flies. Fill in the below mention blanks.

1. The wings are missing in mutant fly L, which is likely the result of a mutation in__ .
2. Mutant fly X has lost the head and thorax. The gene most likely responsible for this mutation is.
3. Thoracic and abdominal structures are missing in mutant fly Q. The gene most likely responsible for this mutation is .
4. Mutant fly F has predominantly lost abdominal structures, which is likely the result of a mutation in _ .
5. The mutation observed in mutant fly O resulted in defects within the anterior or posterior regions of each segment. The gene that most likely caused this mutation is _.
6. Segment-sized sections of every other segment are missing in mutant fly Z. One likely candidate gene is ____

a. hunchback (a gap gene)
b. even-skipped (a pair-rule gene)
c. wingless (a segment-polarity gene)
d. knirps (a gap gene)
e. hedgehog (a segment-polarity gene)
f. Kruppel (a gap gene)

The gap genes are genes expressed during embryonic development of some arthropods. Loss of function mutations of the gap genes are responsible to produce structural "gaps" in the corresponding region of the embryo. The gap genes are transcription factors that modulate the expression of pair-rule genes, which in turn are required for embryonic development of the alternate segments. On the other hand, the segment polarity genes are involved in determining the anterior/posterior axis of each segment (the segment polarity network). In the embryo, segment-polarity genes are expressed at specific localizations only after the expression of gap and pair-rule genes.