Question

how the plants obtainted nitrogen

Answer 1

•Plants which can photisynthesis obtain nitrogen either from the soil or from fertilizers.

•Insectivorous plants obtain nitrogen by eating insects

Answer 2

plants cannot obtain nitrogen directly from atmosphere. so they obtain nitrogen differently:-
1. leguminous plants or legumes have root nodules. this provide a shelter for a bacteria named rhizobium to live. in return it converts atmospheric nitrogen into soluble form(nitrite and nitrate)so that plants can take it.

2. insectivorous plants fulfill their nitrogen requirement by feeding upon insects.

3. other plants get nitrogen from fertilizers and manures that people add into soil.