How many arteries are in your heart?

Why do oceanic plates tend to subduction when colliding with a continental plate

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

Which of the following is not associated with invasive species?