Question

Which of the following is a form of nitrogen that can be directly absorbed by plants?

• A. Nitrogen gas
• B. Nitrate
• C. Nitrogen oxide
• D. Nitrogen sulphide

Answer 1

The correct option is B Nitrate

Plants cannot use atmospheric nitrogen directly so it is converted into a suitable absorbable form by the process of nitrogen fixation.
The atmospheric nitrogen is converted into ammonia by the process of ammonification. This ammonia is then converted into nitrite and then into nitrate by the process of nitrification.
Nitrate is the form of the nitrogen which can be directly absorbed and used by the plants for making amino acids, which are needed to make proteins.