Biology Regents Practice Exam

What role do bacteria play in the nitrogen cycle when organisms release ammonia?

1. Bacteria make nitrogen gas available for plants

2. Bacteria decompose organic matter

3. Bacteria use nitrogen to make amino acids

4. Bacteria contribute to air quality and humidity

The correct answer is: Bacteria use nitrogen to make amino acids

In the context of the nitrogen cycle, when organisms break down and release ammonia, bacteria play a crucial role in transforming that ammonia into forms that can be used by other organisms, particularly plants. One of the key roles of bacteria is the process of ammonification, where decomposer bacteria break down organic matter, leading to the release of ammonia. When bacteria utilize nitrogen from ammonia, they convert it into amino acids through the process of assimilation. These amino acids are vital as they serve as the building blocks for proteins, which are essential for growth and various biological processes in organisms, including plants and animals. Thus, the correct answer highlights the significance of bacteria in making nitrogen available in a form that is assimilable by living organisms, which is integral to the overall health of ecosystems and the continuation of the nitrogen cycle.