AP Environmental Science Flashcards: The Nitrogen Cycle

What this deck covers

This deck focuses on The Nitrogen Cycle, giving you a quick way to review the definitions, rules, and examples that matter most for AP Environmental Science.

How to use these flashcards

Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Flashcard 1: Identify the key enzyme used by bacteria to fix nitrogen.

Answer: Nitrogenase. Catalyzes the energy-intensive conversion of $N_2$ to $NH_3$.

Flashcard 2: Identify the product when nitrogen gas is fixed by bacteria.

Answer: Ammonia ($NH_3$). Direct product of nitrogen fixation by bacterial nitrogenase.

Flashcard 3: Name one impact of industrial nitrogen fixation.

Answer: Increased crop yields. Synthetic fertilizers dramatically boost agricultural productivity.

Flashcard 4: Which process releases ammonium ions from organic matter?

Answer: Ammonification. Bacterial decomposition converts organic nitrogen to inorganic forms.

Flashcard 5: What is the primary impact of nitrogen oxides in the atmosphere?

Answer: Acid rain formation. Nitrogen oxides react with water to form nitric acid.

Flashcard 6: What is the first step in the nitrogen cycle that involves atmospheric nitrogen?

Answer: Nitrogen fixation. Converts inert atmospheric $N_2$ into reactive compounds.

Flashcard 7: State the role of lightning in the nitrogen cycle.

Answer: Nitrogen fixation. High energy electrical discharge breaks $N_2$ bonds naturally.

Flashcard 8: What is the process called when plants uptake nitrates from the soil?

Answer: Assimilation. Plants absorb nitrogen compounds through their root systems.

Flashcard 9: Name the process that involves the conversion of ammonium to nitrite.

Answer: Nitrification. First oxidation step in the two-stage nitrification process.

Flashcard 10: Which human activity contributes significantly to nitrogen fixation?

Answer: Fertilizer production. Industrial Haber-Bosch process creates synthetic nitrogen compounds.

Flashcard 11: Identify the nitrogen compound that plants primarily absorb from soil.

Answer: Nitrates ($NO_3^-$). Highly soluble and mobile form preferred by most plants.

Flashcard 12: Which soil bacteria convert ammonia into nitrites?

Answer: Nitrifying bacteria. First step in two-stage nitrification process.

Flashcard 13: Which gas is released during the process of denitrification?

Answer: Nitrogen gas ($N_2$). Returns nitrogen to atmosphere, completing the cycle.

Flashcard 14: Identify the key enzyme used by bacteria to fix nitrogen.

Answer: Nitrogenase. Catalyzes the energy-intensive conversion of $N_2$ to $NH_3$.

Flashcard 15: What is the main form of nitrogen found in fertilizers?

Answer: Ammonium nitrate. Common synthetic fertilizer providing readily available nitrogen.

Flashcard 16: What organisms primarily perform nitrogen fixation?

Answer: Nitrogen-fixing bacteria. Contain nitrogenase enzyme that converts $N_2$ to $NH_3$.

Flashcard 17: What is the chemical formula for ammonia?

Answer: $NH_3$. Product of nitrogen fixation with one nitrogen and three hydrogens.

Flashcard 18: Identify the nitrogen compound that contributes to greenhouse gas emissions.

Answer: Nitrous oxide ($N_2O$). Potent greenhouse gas with 300 times warming potential of $CO_2$.

Flashcard 19: Which process involves the conversion of nitrates back to nitrogen gas?

Answer: Denitrification. Anaerobic bacteria reduce nitrates, completing the nitrogen cycle.

Flashcard 20: Identify one environmental issue caused by excess nitrogen from agriculture.

Answer: Water pollution. Runoff causes eutrophication and groundwater contamination.

Flashcard 21: Which process in the nitrogen cycle is anaerobic?

Answer: Denitrification. Requires oxygen-free environment for bacteria to function.

Flashcard 22: Identify the product when nitrogen gas is fixed by bacteria.

Answer: Ammonia ($NH_3$). Direct product of nitrogen fixation by bacterial nitrogenase.

Flashcard 23: What is the chemical formula for nitrous oxide?

Answer: $N_2O$. Two nitrogen atoms bonded to one oxygen atom.

Flashcard 24: State the role of legumes in the nitrogen cycle.

Answer: Host nitrogen-fixing bacteria. Provide shelter and nutrients for nitrogen-fixing bacteria.

Flashcard 25: What is the main function of nitrogen-fixing bacteria in root nodules?

Answer: Convert $N_2$ to ammonia. Use nitrogenase to break triple bonds in atmospheric nitrogen.

Flashcard 26: Name one impact of industrial nitrogen fixation.

Answer: Increased crop yields. Synthetic fertilizers dramatically boost agricultural productivity.

Flashcard 27: What is the final product of the denitrification process?

Answer: Nitrogen gas ($N_2$). Completes the nitrogen cycle by returning to atmosphere.

Flashcard 28: Which organism type is crucial for the nitrogen cycle in aquatic systems?

Answer: Cyanobacteria. Blue-green algae that fix nitrogen in marine environments.

Flashcard 29: Identify the process that bacteria use to convert ammonia into nitrite.

Answer: Nitrification. First step in nitrification where ammonia becomes nitrite.

Flashcard 30: Identify the process that converts atmospheric nitrogen into ammonia.

Answer: Nitrogen fixation. Breaks the strong triple bond in $N_2$ to create bioavailable forms.