Problem 4 - Campbell Biology

Question

Nitrifying bacteria participate in the nitrogen cycle mainly by \begin{equation}\begin{array}{l}{\text { (A) converting nitrogen gas to ammonia. }} \\ {\text { (B) releasing ammonium from organic compounds, thus }} \\ {\text { returning it to the soll. }} \\ {\text { (C) converting ammonium to nitrate, which plants absorb. }} \\ {\text { (D) incorporating nitrogen into amino acids and organic }}\end{array}\end{equation}

Step-by-Step Solution

Answer

(C) converting ammonium to nitrate, which plants absorb.

Step 1 - Understanding Nitrogen Cycle and Nitrifying Bacteria

The nitrogen cycle is a series of processes by which nitrogen and its compounds are interconverted in the environment and in living organisms. Nitrifying bacteria play a crucial role in this cycle.

Step 2 - Identify the Roles of Nitrifying Bacteria

Nitrifying bacteria are primarily involved in the nitrification process, which is the conversion of ammonium (NH₄⁺) to nitrate (NO₃⁻).

Step 3 - Analyze the Options

Examine the provided options to determine which one corresponds to the action of nitrifying bacteria:(A) Converting nitrogen gas to ammonia - This process is called nitrogen fixation, usually performed by nitrogen-fixing bacteria, not nitrifying bacteria.(B) Releasing ammonium from organic compounds - This process is known as ammonification, carried out by decomposer bacteria, not nitrifying bacteria.(C) Converting ammonium to nitrate, which plants absorb - This matches the role of nitrifying bacteria.(D) Incorporating nitrogen into amino acids and organic compounds - This process is generally done by plants and other organisms, not nitrifying bacteria.

Step 4 - Choose the Correct Answer

Based on the analysis, the correct option is (C) converting ammonium to nitrate, which plants absorb.

Key Concepts

nitrifying bacteria

Nitrifying bacteria are essential players in the nitrogen cycle. These bacteria are special because they help convert nitrogen from one form to another, making it accessible to plants. They mainly fall into two categories:

• Nitrosomonas: These bacteria convert ammonium (NH₄⁺) into nitrite (NO₂⁻).
• Nitrobacter: These bacteria take the nitrite (NO₂⁻) and convert it into nitrate (NO₃⁻).

This two-step process is crucial for plant nutrition, as plants can absorb nitrate more easily than ammonium. Without nitrifying bacteria, plants would struggle to get the nitrogen they need.
They work efficiently in well-aerated soils, as they require oxygen to perform these conversions. Additionally, these bacteria are sensitive to pH levels; they thrive best in neutral to slightly alkaline soils.

nitrification

Nitrification is a key process in the nitrogen cycle. This process involves the conversion of ammonium (NH₄⁺) into nitrate (NO₃⁻) via a two-step process that involves two types of nitrifying bacteria.

• The first step is called 'ammonium oxidation,' where Nitrosomonas bacteria convert ammonium into nitrite (NO₂⁻).
• The second step is 'nitrite oxidation,' where Nitrobacter bacteria convert nitrite into nitrate (NO₃⁻).

Nitrification is important because nitrate is the preferred form of nitrogen that plants absorb through their roots. This conversion process helps in maintaining soil fertility and supports plant growth. Proper soil conditions, such as good aeration and a balanced pH, are essential for efficient nitrification. Without this process, the nitrogen available in the soil would be less effective, limiting plant development.

ammonium to nitrate conversion

The conversion of ammonium (NH₄⁺) to nitrate (NO₃⁻) is a vital part of the nitrogen cycle and is primarily achieved through the process of nitrification. This conversion process is split into two main steps:

• Ammonium oxidation: Here, Nitrosomonas bacteria convert ammonium into nitrite (NO₂⁻).
• Nitrite oxidation: Next, Nitrobacter bacteria convert nitrite into nitrate (NO₃⁻).

Plants benefit from this conversion because nitrate is more readily absorbed by their root systems. The availability of nitrate improves the efficiency of nitrogen uptake, promoting better plant health and growth.
Understanding this conversion is essential for agriculture and environmental science, as it explains how nutrients cycle through ecosystems. Proper soil management practices can enhance this natural process, ensuring that crops receive the essential nutrients they need.