Question

Nitrogen-fixing bacteria are important because

• A. They turn nitrogen from the air into nitrogen compounds in the soil
• B. They are essential for plants being able to carry out photosynthesis
• C. They break up dead plants and animals in the soil
• D. They release excess nitrogen from the soil into the atmosphere

Answer 1

The correct option is A They turn nitrogen from the air into nitrogen compounds in the soil

Cells are built out of protein molecules; these are organic molecules built around carbon and nitrogen. To grow, plants need protein, and for this plants need nitrogen. Nitrogen is a very essential element and is found in the various forms like the proteins, nucleic acids (DNA & RNA ) some vitamins, alkaloids, and urea. Plants cannot absorb atmospheric nitrogen but Nitrogen-fixing bacteria take atmospheric nitrogen (N2N2) and convert it to nitrates (NONO) in the soil. This is then absorbed by plants.

So, the correct answer is 'They turn nitrogen from the air into nitrogen compounds in the soil'.