The Nitrogen Cycle diagram explains how nitrogen moves through the environment, highlighting key processes such as nitrogen fixation, nitrification, decomposition, and feeding.

Here's the correct labeling for the numbered boxes in The Nitrogen Cycle diagram, based on the provided word bank and scientific understanding of the nitrogen cycle:

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✔ Labeled Boxes:

1. Nitrogen Fixation
→ This is the process where atmospheric nitrogen (N₂) is converted into ammonia (NH₃) by certain bacteria (like *Rhizobium* in root nodules). The diagram shows “Nitrogen in the air” being taken up by “Bacteria in soil” or “Bacteria in root nodules,” which matches nitrogen fixation.

2. Uptake by roots
→ Plants absorb nitrogen compounds (like nitrates NO₃⁻ or ammonium NH₄⁺) from the soil through their roots. Box 2 points to a plant taking in “Nitrate ions” — this is uptake by roots.

3. Feeding
→ Animals consume plants (or other animals) to obtain nitrogen-containing molecules (proteins, nucleic acids). Box 3 shows an animal eating a plant — this represents feeding.

4. Decomposition
→ When organisms die or produce waste, decomposers (like fungi and bacteria) break down organic matter and release ammonium (NH₄⁺) back into the soil. Box 4 shows “Death and waste” leading to “Ammonium ions” — that’s decomposition.

5. Nitrifying Bacteria
→ These bacteria convert ammonium (NH₄⁺) into nitrite (NO₂⁻), then into nitrate (NO₃⁻). Box 5 shows “Ammonium ions” → “Nitrate ions” — this is nitrification, done by nitrifying bacteria.

6. Denitrifying Bacteria
→ These bacteria convert nitrates (NO₃⁻) back into nitrogen gas (N₂), releasing it into the atmosphere. Box 6 shows “Nitrate ions” → “Nitrogen in the air” — this is denitrification.

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✔ Key Points Completed:

> • A key type of organism involved in the cycling of nitrogen are bacteria.
> • Nitrogen fixing bacteria are found in the root nodules of legumes and can convert inert nitrogen gas into nitrogen-containing ions.
> • Nitrifying bacteria can convert ammonium ions to nitrate ions, which can be taken up by the roots of plants.
> • Some bacteria, found in water-logged soils, convert nitrates back into nitrogen gas; these are known as denitrifying bacteria.

*(Note: “Legumes” is implied by the context — plants like beans, peas, clover — that host nitrogen-fixing bacteria in root nodules.)*

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🔄 Summary of the Nitrogen Cycle Flow:

1. Atmospheric N₂ → Fixed by Nitrogen Fixation (by bacteria) → becomes Ammonia/NH₃
2. Ammonia → Converted to Nitrate via Nitrifying Bacteria
3. Plants take up Nitrate via Uptake by roots
4. Animals eat plants → Feeding
5. Organisms die → Decomposition → releases Ammonium
6. Denitrifying Bacteria convert Nitrate → back to N₂ gas → released to atmosphere

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✔ All labels match the biological processes accurately. The diagram illustrates the essential roles of bacteria and the movement of nitrogen through ecosystems.

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