Which two of the following choices are examples of commons?

A. Personal computers

B. National parks

C. Private homes in a neighborhood

D. Units in an apartment complex

E. Groundwater

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 structure in the cardiovascular system connect arteries to veins?

According to theories of how life began, how did early organic molecules begin to separate from the outside world? a: specialized enzymes were required b: chains of amino acids created a barrier c: formation of microspheres or vesicles d: rna catalyzed the formation of membranes