Why do you think it’s important that cell membranes are selectively permeable?

So that they don't explode.

AKA with a thing called osmosis (transportation of water through cells.)

So they will not explode.

the father in the first generation probably had the recessive colorblind trait in his x chromosome. if he and his wife both had the colorblind trait, even if she had 1 recessive and 1 dominant, then that trait would be passed on to their kids.

(since you didn't attach the family tree this is just an assumption)