Answer:
When water falls and seeps into the ground it actually interacts with the lithosphere
The both decrease genetic variation
Crossing two true breeding parents with opposite parents is the key:
Assume W is straight wing and w is curly.
Then you are crossing WW with ww
This will result in ALL Ww as offspring - so all straight offspring
If you then cross Ww x Ww you end up with a mix of
WW (1), Ww (2) and ww (1) - so a mix of straight and curly
Answer:
P generation has straight wings and curly wings
F1 has all straight wings
F2 has straight wings and curly wings