Practice Flashcard: Nitrogen, Phosphorous and Carbon Cycles

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What is the nitrogen cycle?

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The nitrogen cycle is the process by which nitrogen is converted between its various chemical forms, including nitrogen fixation, nitrification, denitrification, and ammonification.

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What is nitrogen fixation?

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Nitrogen fixation is the process of converting atmospheric nitrogen (N2) into a form that plants can use, such as ammonium (NH4+) or nitrate (NO3-).

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What is nitrification?

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Nitrification is the biological process in which ammonia (NH3) is converted into nitrites (NO2-) and then into nitrates (NO3-) by bacteria.

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What is denitrification?

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Denitrification is the process by which nitrates (NO3-) are converted back into nitrogen gas (N2), returning nitrogen to the atmosphere.

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What is ammonification?

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Ammonification is the process of converting organic nitrogen from dead plants and animals into ammonia (NH3) by decomposers.

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What is assimilation in the nitrogen cycle?

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Assimilation is the process by which plants absorb ammonium ions (NH4+) and nitrate ions (NO3-) from the soil to create organic molecules like DNA and proteins.

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Why can't plants and animals use nitrogen directly from the air?

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Plants and animals cannot use nitrogen directly from the air because it exists as a diatomic molecule (N2) that is not reactive and must be converted into usable forms.

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What is the role of sulfur dioxide in the environment?

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Sulfur dioxide (SO2) can contribute to air pollution and acid rain when it reacts with water vapor in the atmosphere.

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What is formed when sulfur dioxide reacts with oxygen?

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When sulfur dioxide reacts with oxygen, it forms sulfur trioxide (SO3), which can further react with water to form sulfuric acid (H2SO4).

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How do animals obtain nitrogen?

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Animals obtain nitrogen by consuming plants or other animals that contain nitrogen in organic compounds.