Quick question: did I do this correctly?

What does it mean for a cell membrane to be selectively permable

The galapagos island contain 13 species of finches four of the species are seen here it is believed that all of the species had one common ancestor and overtime

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