A(n) is a molecule, cell, or organ that directly carries out a response to a stimulus and restores homeostasis.

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

Anormal strand of dna is shown below, followed by the same strand of dna after mutations have occurred.

Why are current extinctions of concern to enviromentalists?