Why protonephridia are called lame cells

Its has a cavity called cilia when its cavity undulate or moves it resembles a flickering candle

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)

this is a good question! i'll do some research and come back when i have the answer!