Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

[Q]: After fertilization, a zygote forms into two cells.
[A]: After fertilization, how many cells does a zygote form into?


[Q]: Axillary buds in the axils of leaves and stems give rise to branches.
[A]: What in the axils of leaves and stems give rise to branches?


[Q]: The bird ancestor that lived in trees developed wings, which is commonly associated with birds.
[A]:
The bird ancestor that lived in trees developed what feature commonly associated with birds?