The Nitrogen Cycle
Jack Wilson
7 min read
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Study Guide Overview
This study guide covers the nitrogen cycle, including why nitrogen is important as a macronutrient and limiting nutrient. It details the cycle's key steps: nitrogen fixation, nitrification, assimilation, mineralization, and denitrification, emphasizing the role of bacteria. The guide also explains human impacts like fertilizer overuse, eutrophication, and effects on species richness. Finally, it provides practice questions and exam tips.
#AP Environmental Science: The Nitrogen Cycle 🌿
Hey there, future AP Environmental Science superstar! Let's dive into the nitrogen cycle – it's a big deal, but we'll break it down so it's super easy to understand. Remember, this isn't AP Chem, so we're focusing on the big picture and impacts, not memorizing every single reaction. Let's get started!
#Why Nitrogen Matters
Nitrogen is a macronutrient, essential for all living things. It's a key component of:
- Proteins
- DNA
- Other vital biomolecules
Basically, no nitrogen = no life! The nitrogen cycle is how this crucial element moves between the atmosphere, land, and water.
Nitrogen is a limiting nutrient, meaning it's essential but often in short supply. This is why it's a common ingredient in fertilizers.
Think of nitrogen as the 'building block' of life. Just like you need bricks to build a house, plants and animals need nitrogen to build their bodies.
#The Nitrogen Cycle: Step-by-Step 🔄
Here's a simplified journey of nitrogen through the environment:
#1. Nitrogen Fixation 💨➡️🌱
- What it is: Conversion of atmospheric nitrogen gas (N2), which is unusable by most organisms, into usable forms like ammonia (NH3) or nitrate (NO3).
- How it happens:
- Biotic Fixation: Nitrogen-fixing bacteria (like those in the roots of legumes) convert N2 into ammonia (NH3), which quickly becomes ammonium (NH4+).
- Abiotic Fixation: Lightning, fires, and fossil fuel combustion can convert N2 directly into NO3. Quick Fact
78% of the Earth's atmosphere is nitrogen gas (N2), but it's not usable by most organisms until it's 'fixed'.
#2. Nitrification 🌱➡️NO2-➡️NO3-
- What it is: Ammonia (NH3) and other nitrogen compounds are converted into nitrite (NO2-) and then nitrate (NO3-).
- How it happens: Bac...
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