Answer:
The dominant curled wing allele is also a recessive lethal.
Explanation:
If we look at the F2 ratio we see that : Â
curled wings: straight wings= 160:80
                        =2:1
Hence, Â if curled wings is considered to be a dominant trait then Curled wings * straight wings
Dd x dd
Punnet square will be as follows :
      d           d
D  |   Dd  |     Dd
d   |   Dd  |     dd
Hence in order to get F2
Dd x dd
Punnet square will be the same as above if the F1 cross is Dd* Dd
    D   d
D DD Dd
d Dd dd
if DD is lethal then the ratio is
Dd:dd=2:1
that is curled wings: straight wings=2:1
Hence, The dominant curled wing allele is also a recessive lethal.