Nitrogen is available to plants only in the form of Naim 12:33 AP Biology Nitrogen is available to plants only in the form of A) N2 in the atmosphere. B) nitrite ions in the soil. C) uric acid from animal excretions. D) amino acids from decomposing plant and animal proteins. E) nitrate ions in the soil. Answer: E Learn More : Share this Share on FacebookTweet on TwitterPlus on Google+