What is a change in an organism's surroundings or environment that causes it to react or respond?

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

What are some things that limit population growth?

Other than earth, is also known to have magnetic pole reversal? a: venus b: mars c: earths moon d: the sun