The answer is : crossing over can increase genetic variations during meiosis
<span>Having things other than chlorophyll (or bacteriochlorophyll or bacteriorhodopsin) absorbing the light will decrease productivity in any ecosystem whose biotic basis is photoautotrophs.</span>
I think you wrote this wrong? Is it not round rr vs wrinkled RR?? I'll answer it with that assumption:
You are crossing a rr with an RR:
You only get Rr back so they will phenotypically be all wrinkled
If you are crossing rr with an Rr (so a heterozygote wrinkled):
50% will be Rr (wrinkled)
50% will be rr (round)
See my picture for the Punnett Squares for both answers!