Name the five areas of study in which biologists are involved

In which situations is the principle of cross-cutting relationship useful in determining relative age?

What organ is the first to receive nutrients that have been absorbed from the digestive tract?

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