Answer:
Option (2).
Explanation:
Ames test is used to identify the mutageneicity of the compound. The bacteria are treated with chemicals in the nutritive environment to determine whether the substance can acts as a mutagen or not.
The bacteria that can restore the biosyntheic activity in the environment can be considered as mutagen. The mutant bacteria can be easily identified in the Ames test.
Thus, the correct answer is option (2).
<span>The nitrogen cycle could not exist without first nitrogen. The cycle is about this specific element which goes to show that if this element is not present then, there will not be any nitrogen cycle. Also, an important factor for the cycle is the presence of the bacteria and other microorganism which are needed for the fixation. </span>