Educational worksheet on the nitrogen cycle, featuring a labeled diagram and fill-in-the-blank questions to explain how nitrogen moves through ecosystems.

Problem Analysis:

The worksheet is about the Nitrogen Cycle, a crucial biogeochemical cycle that describes how nitrogen moves through the environment. The task involves filling in blanks based on the provided diagram and understanding of the nitrogen cycle.

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Step-by-Step Solution:

#### Part 1: Filling in the Blanks in the Introduction
1. "Nitrogen makes up _____ percent of Earth’s atmosphere."
- Nitrogen makes up 78% of Earth's atmosphere.
- Answer: 78

2. "It's also an important part of _____ things."
- Nitrogen is an essential component of many biological molecules.
- Answer: living

3. "Nitrogen is found in proteins, _____, and chlorophyll."
- Nitrogen is a key component of nucleic acids (DNA and RNA).
- Answer: nucleic acids

4. "The nitrogen cycle moves nitrogen through the abiotic and biotic parts of _____."
- The nitrogen cycle involves both living organisms (biotic) and non-living components (abiotic) of the ecosystem.
- Answer: ecosystems

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#### Part 2: Analyzing the Diagram to Fill in the Blanks

1. "Even though _____ makes up most of Earth’s atmosphere, plants cannot use this nitrogen gas to make organic compounds for themselves and other _____."
- Nitrogen gas (\( \text{N}_2 \)) makes up most of the atmosphere, but it is not directly usable by plants or other organisms.
- Plants and other organisms need nitrogen in a more accessible form.
- Answers: nitrogen gas, organisms

2. "The two nitrogen atoms in a molecule of nitrogen gas are held together by a very stable triple bond. This bond must be _____ for the nitrogen to be used."
- The triple bond in \( \text{N}_2 \) is very strong and must be broken for nitrogen to be usable.
- Answer: broken

3. "The nitrogen gas must be changed to a form called _____, which plants can absorb through their _____."
- Nitrogen gas is converted into forms like nitrates (\( \text{NO}_3^- \)), which plants can absorb through their roots.
- Answers: nitrates, roots

4. "The process of changing nitrogen gas to nitrates is called _____."
- The process of converting nitrogen gas into nitrates is called nitrogen fixation.
- Answer: nitrogen fixation

5. "It is carried out by nitrogen-fixing _____."
- Nitrogen-fixing bacteria perform this process.
- Answer: bacteria

6. "The bacteria live in soil and root nodules of _____, such as peas."
- Nitrogen-fixing bacteria often live in symbiotic relationships with legumes (plants like peas).
- Answer: legumes

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#### Part 3: Decomposition and Further Nitrogen Conversion

1. "When plants and other organisms die, decomposers _____ their remains. In the process, they release nitrogen in the form of _____ ions."
- Decomposers break down dead organisms and release nitrogen as ammonium ions (\( \text{NH}_4^+ \)).
- Answers: break down, ammonium

2. "This process is called _____."
- The breakdown of organic matter by decomposers is called ammonification.
- Answer: ammonification

3. "_____ bacteria change the ammonium ions into _____ and _____."
- Nitrifying bacteria convert ammonium ions into nitrites (\( \text{NO}_2^- \)) and then into nitrates (\( \text{NO}_3^- \)).
- Answers: nitrifying, nitrites, nitrates

4. "Some of the nitrates are used by _____."
- Plants absorb nitrates from the soil.
- Answer: plants

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Final Answer:

\[
\boxed{
\begin{aligned}
&\text{78, living, nucleic acids, ecosystems,} \\
&\text{nitrogen gas, organisms, broken, nitrates, roots,} \\
&\text{nitrogen fixation, bacteria, legumes,} \\
&\text{break down, ammonium, ammonification,} \\
&\text{nitrifying, nitrites, nitrates, plants.}
\end{aligned}
}
\]