I am the mythological figure who ferried the dead across the River Styx into Hades (the underworld). Who am I? (Hint: I am a moon)

Why do leaves change color in the fall? green pigments break down and no longer mask the color of chlorophyll. chlorophyll breaks down and no longer masks the colors of other pigments. red- and yellow-colored pigments grow and mask green-colored chlorophyll. green-colored chlorophyll breaks down and turns red and yellow.

A(n) is a molecule influences the way that a molecule reacts.

What blood vessels carry blood to the heart? away from the heart?