Biogeochemical Cycles (nitrogen cycle)

Introduction

The nitrogen cycle represents one of the most important nutrient cycles found in terrestrial ecosystems. Nitrogen is used by living organisms to produce a number of complex organic molecules like amino acids, proteins, and nucleic acids. The majority of nitrogen is found in the atmosphere, where it exists as a gas (mainly N2). Other major reserves of nitrogen include organic matter in soil and the oceans. Despite its large quantity in the atmosphere, nitrogen is often the most limiting nutrient for plant growth. This problem occurs because most plants can only take up nitrogen in two solid forms: ammonium ion (NH4 + ) and the ion nitrate (NO3 - ). Specialized bacteria “fix” nitrogen, converting it to a form that can be used by organisms. By fixing nitrogen, these bacteria are a critical link between atmospheric nitrogen and life on Earth. 

Task

In this webquest you will search for information that will answer questions about the nitrogen cycle using the listed websites. Answer all questions in the spaces provided. The easiest way to answer the questions is to take your time! Don’t rush through the websites, take your time finding the correct answer.

Process

Evaluation

1. Why is nitrogen important to organisms? 

2.What must happen to nitrogen before plants and animals can use it?

3. What organisms are able to “fix”, or convert, nitrogen to be usable by plants? How else might nitrogen be “fixed” or converted? 

4. Draw and label a graphic showing your understanding of the nitrogen cycle

5.Once in plants and animals, explain how does nitrogen return to the atmosphere?

Conclusion

What did you conclude?