OCR GCSE Biology 2026 – 400 Free Practice Questions to Pass the Exam

Nitrifying bacteria play a crucial role in the nitrogen cycle by converting ammonia into nitrates. This process is significant because ammonia, which can be toxic to plant life at high concentrations, is transformed into nitrates, which are a more usable form of nitrogen for plants.

The conversion occurs in two main steps. First, ammonia is oxidized to nitrites by a group of nitrifying bacteria known as ammonia-oxidizers. Then, another group of bacteria, called nitrite-oxidizers, further oxidizes the nitrites into nitrates. This transformation is essential for maintaining the fertility of soils, providing plants with the necessary nutrients to grow.

This process not only supports plant health but also contributes to the overall balance of nitrogen in ecosystems, highlighting the significance of nitrifying bacteria in both agriculture and natural environments.