Diffusion of water across a selectively permeable membrane is called

I’m doing some practice exam questions for biology, and i’m not sure how to do these 3 parts to the question.

The concept of keystone species is controversial among ecologists because most organisms are highly interdependent. if each of the trophic levels is dependant on all others how can we say one is most important

1. in a certain species of plant, the color purple (p) is dominant to the color white (p). according the punnett square, what is the probability of and offspring being white? 50%25%0%100% 2. in a certain species of plant, the color purple (p) is dominant to the color white (p). according the punnett square, what is the probability of and offspring being white? 0%100%50%25%(picture 1 is for question 1, and picture 2 is for question 2)