​Have we learned about any cycles lately?

Recall that a cycle is a series of events that repeats in a predictable pattern. In a previous lesson, you learned that the carbon cycle moves carbon atoms between living and nonliving parts of an ecosystem. As carbon moves through the carbon cycle, chemical reactions change the carbon into different forms. Review the carbon cycle in the diagram below.

​Recall that the carbon cycle has processes that move carbon between different reservoirs.

• Plants perform photosynthesis to convert carbon dioxide into glucose.

• Eukaryotes perform cellular respiration, which changes the carbon found in glucose into carbon dioxide.

• Combustion releases carbon dioxide from fossil fuels as they burn.

In today's lesson, you will learn about a similar nutrient cycle.

Do we know anything about the Nitrogen Cycle?

Can we make a hypothesis about what it is now that we know what the carbon cycle is?

​The nitrogen cycle is the process that moves nitrogen atoms between living and nonliving parts of an ecosystem. Plants take a form of nitrogen from the soil and use it to build molecules. That nitrogen passes through the food chain as organisms consume the plants. In today's lesson, you will learn about the nitrogen cycle. You will complete an interactive that traces the path of nitrogen atoms through the nitrogen cycle.

The Nitrogen Cycle Explained

​Living things need nitrogen to build proteins, DNA, and chlorophyll. Nitrogen gas, N₂, is the most common gas in Earth's atmosphere. However, organisms cannot use nitrogen gas. During the nitrogen cycle, chemical reactions rearrange the nitrogen atoms to form nitrate. Nitrate is a compound containing nitrogen that plants can use. A protein is a substance that plants use this nitrogen to build, and that is important for living things to survive. 

​Did You Know? In 60 Seconds: Nitrogen Fixation

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