Question

In which natural cycle must an important gas in Earth's atmosphere be fixed before plants can use it?

A sulfur cycle
B carbon cycle
C nitrogen cycle
D oxygen cycle

Answer 1

The answer is C . nitrogen cycle

Answer 2

Answer: Nitrogen Cycle

Explanation:

The nitrogen cycle is one of the most important biogeochemical cycle. It is an essential gas present in the atmosphere.

It is vital for the growth of plants and animals. Animals derive this nutrient by eating plants. But plants cannot take it in the form of nitrogen gas it takes it in different forms.

This is because the nitrogen fixing bacteria fixes nitrogen which means it converts nitrogen in the form which can be used by the plants.

So, the correct answer is nitrogen cycle as it needs to be modified before being used by plants.