Sensory Neurons and Motor Neurons. Motor neurons would make you withdraw your hand spontaneously when it touches something hot.
It some back to earth since gravity pulls it down
Enzymes reduce the activation energy allowing chemical reactions to occur in living things.
In light reactions, a molecule of chlorophyll absorbs one photon of light, causing a chlorophyll electron to transfer to a higher energy level. ... Chlorophyll then replaces the lost electrons from water molecules. The oxygen atoms form oxygen gas while the hydrogen atoms form protons and electrons.