The nitrogen cycle could not exist without what
The Correct Answer and Explanation is:
Correct Answer: Bacteria
The nitrogen cycle could not exist without bacteria, which are essential for converting nitrogen into forms that plants and animals can use. Nitrogen is a vital element for all living things because it is a major component of proteins and DNA. However, most organisms cannot use nitrogen gas (N₂) from the atmosphere directly. This is where bacteria play a crucial role.
There are several types of bacteria involved in the nitrogen cycle:
- Nitrogen-fixing bacteria (such as Rhizobium) convert nitrogen gas from the atmosphere into ammonia (NH₃), which plants can absorb. These bacteria often live in the root nodules of legumes (like beans and peas) and form a symbiotic relationship with the plant.
- Nitrifying bacteria (like Nitrosomonas and Nitrobacter) convert ammonia into nitrites (NO₂⁻) and then into nitrates (NO₃⁻), which are more readily absorbed by plants. This process is known as nitrification.
- Denitrifying bacteria (such as Pseudomonas and Clostridium) convert nitrates back into nitrogen gas, releasing it into the atmosphere. This step, called denitrification, completes the nitrogen cycle and maintains a balance in the ecosystem.
- Decomposers (including bacteria and fungi) break down dead plants and animals, releasing ammonia into the soil through a process called ammonification.
Without bacteria, the nitrogen in the atmosphere would remain unusable to most living organisms, and ecosystems would collapse due to a lack of usable nitrogen for protein synthesis and growth. Bacteria ensure that nitrogen continuously moves through the air, soil, plants, and animals in a sustainable loop. Therefore, they are indispensable to the functioning of the nitrogen cycle.
