Identify the accessory structure of the skin indicated by the arrows

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.

x would be the most and the least would be y because there are more fruit   and seeds than flock z has insects

oxygen = 21% of the atmosphere

nitrogen = 78%

carbon dioxide = 0.1%

argon =0.934%