Question

Nitrifying bacteria \(\mathrm{O}_{\mathrm{j}} \mathrm{jec}\) (a) oxidize ammonia to nitrates (b) convert free nitrogen to nitrogen (c) convert proteins into ammonia (d) reduce nitrates to free nitrogen.

Short answer

Nitrifying bacteria oxidize ammonia to nitrates.

Step-by-step solution

Understanding Nitrifying Bacteria

Nitrifying bacteria are a type of bacteria that play an important role in the nitrogen cycle. Their primary function is to transform ammonia (NH3) into nitrite (NO2-) and then into nitrate (NO3-). This is a part of the process called nitrification, which is essential for the conversion of nitrogen from a form that is unusable by most plants into a form that they can absorb and use as a nutrient.

Identifying the Correct Function

From the functions listed in the options, we need to identify which one accurately describes the role of nitrifying bacteria in the nitrogen cycle. We know that these bacteria are involved in the oxidation of ammonia to produce nitrites and nitrates but do not have a role in fixing atmospheric nitrogen or in denitrification directly.

Choosing the Correct Option

Based on what nitrifying bacteria do, the correct answer is: (a) oxidize ammonia to nitrates. They are not responsible for converting atmospheric nitrogen to a different form (b), converting proteins into ammonia (c), or reducing nitrates to free nitrogen (d).

Key concepts

Understanding the Nitrogen Cycle

The nitrogen cycle is a crucial biogeochemical cycle in which nitrogen is converted into multiple chemical forms as it circulates among the atmosphere, terrestrial, and marine ecosystems. It involves several key steps which include nitrogen fixation, nitrification, assimilation, ammonification, and denitrification.

Nitrifying bacteria are primarily involved in the nitrification phase, where they play a significant role in maintaining the cycle's flow. Through their activity, these microorganisms help in converting nitrogen from its unusable form, such as atmospheric nitrogen or ammonia, into compounds like nitrates that plants can readily absorb and utilize. The nitrogen cycle is paramount for plant growth and agriculture since it is the mechanism that ensures the replenishment of nitrogen in the soil.

Exploring the Oxidation of Ammonia

Oxidation is a chemical reaction that involves the transfer of electrons between substances, and in the context of the nitrogen cycle, it specifically refers to the oxidation of ammonia (NH3). This is a two-step process: firstly, ammonia is oxidized to nitrite (NO2-) by certain bacteria, and then further to nitrate (NO3-), which is the more stable form.

This phase of the cycle is particularly important because ammonia, which is a byproduct of organic waste decomposition, can be toxic to plants and animals in high concentrations. By converting ammonia to nitrate, nitrifying bacteria help to detoxify the environment, making nitrogen available for uptake by plant roots. Earth's ecosystems rely on this conversion process to support life and maintain ecological balance.

Breaking Down the Nitrification Process

Nitrification is a two-step aerobic process performed by distinct types of nitrifying bacteria. Firstly, ammonia-oxidizing bacteria (AOB) like Nitrosomonas convert ammonia into nitrites. Then, nitrite-oxidizing bacteria (NOB) such as Nitrobacter take over to oxidize nitrites into nitrates.

This process of nitrification is essential for the nitrogen cycle and occurs naturally in soil and aquatic environments. Having a proper understanding of the nitrification process is critical in fields like agriculture and wastewater management, where managing nitrogen levels is vital for plant growth and environmental protection.