Absorption. They absorb nutrience from dead/dying animals and/or plants.
Explanation:
1 and 17 are highly reactive bc they are almost full or not full at all. they need there last shell to be full in order to be happy, or not reactive. 18 has the noble gases which are not reactive at all bc they have a full valence shell and dont need any other electrons.
Energy input is required as it is the activation energy needed for a reaction to start.
It is during that full moon and the new moon.