Question

Why do you think plants and animals can't use nitrogen as it is found in the atmosphere?

Answer 1

first .... nitrogen is no use of animal as when it reaches the blood ...it will cause nausea and headache.

now for plants ....there is no specialized organ that can take nitrogen ....and stomatal pores is only used for o2 and CO2 ....so it has to take it by soil in form of nitrates !!!