Ontario Grade 9 Science Class Practice Exam

What is the role of fungal and bacterial decomposers in the nitrogen cycle?

1. They convert inorganic nitrates into nitrogen gas

2. They absorb nitrates into plant roots

3. They break down organic nitrogen into inorganic ammonium

4. They convert ammonia into nitrate ions

The correct answer is: They break down organic nitrogen into inorganic ammonium

Fungal and bacterial decomposers play a crucial role in the nitrogen cycle by breaking down organic nitrogen, found in dead plants and animals, into inorganic ammonium. This process, known as ammonification, releases nitrogen in a form that can be used by plants to grow and thrive. Option A is incorrect because it refers to denitrification, where bacteria convert nitrates into nitrogen gas. Option B is incorrect because it describes the process of nitrification, where nitrates are absorbed by plant roots. Option D is incorrect because it also refers to nitrification, where bacteria convert ammonia into nitrate ions. It is important to note that while these processes are important in the nitrogen cycle, they are not the specific role of fungal and bacterial decomposers. Overall, option C is the correct answer as it accurately describes the role of these decomposers in breaking down organic nitrogen