Which motion of particles across a membrane requires energy?

Which of these is not a function of some membrane proteins ? a.allowing polar molecules to enter the cell b.recognizing other types of cells c.receiving messeges from other cells b.carrying messages to oher cells

Which of the following was not a major animal on land during the carboniferous period? amphibians insects both a and b none of the above

Which number represents a basic ph, 4 or 9? numerical answers expected! answer for blank 1: i'll give