Nitrogen Basics
Ammonium (NH4) stays in soil, while nitrate (NO3) is easily leached out. Why do they behave so differently?
NH4 has a positive charge and sticks to soil particles.
Organic nitrogen is converted back to inorganic nitrogen like ammonium through the process of?
Decay
What do plants use nitrogen for inside their cells?
To build amino acids/proteins and DNA
What is the human activity that adds the most reactive nitrogen to the environment?
The use of synthetic fertilizers
What is the most common way that nitrogen fixation occurs?
Nitrogen fixing bacteria
Why is nitrogen essential for living organisms?
Nitrogen is a key component of proteins and nucleic acids, DNA and RNA, both essential for life.
What is denitrification?
The step in the nitrogen cycle where nitrogen returns to the atmosphere.
What happens if plants can’t access enough nitrogen?
They show stunted growth and yellowing leaves due to insufficient protein and chlorophyll production.
How does human activity (like fertilizer use) disrupt the nitrogen cycle?
Excess fertilizer adds too much reactive nitrogen to ecosystems, leading to runoff, eutrophication, and algal blooms in aquatic systems.
Who first uses nitrogen in the food chain?
Plants (producers).
What form of nitrogen do plants take up most easily?
Nitrate
What happens to nitrogen when a plant or animal dies?
Decomposers break down the organic matter and release ammonium through ammonification.
What nitrogen-based compound in the nitrogen cycle is toxic to most living things
Ammonium (NH4)
What is eutrophication?
When aquatic biomes become overly enriched with nutrients, especially nitrogen and phosphorus.
What living thing in the food chain release Ammonium (NH4) into the soil from waste products
Decomposers
What form of nitrogen makes up about 78% of Earth’s atmosphere?
Nitrogen gas (N₂) makes up most of Earth’s atmosphere.
What is it called when plants take in nitrates and make proteins?
Assimilation
How do animals obtain nitrogen?
By eating plants or other animals that contain nitrogen-rich molecules like proteins.
Fossil fuels release not only CO2 but also what compound in the air?
Nitrogen oxides (NO and NO₂)
What uses the process of assimilation in the nitrogen cycle
Plants taking up nitrate (NO₃)
What is the main reservoir of nitrogen on Earth?
The atmosphere
What process turns nitrogen gas (N₂) into ammonia (NH₃)?
Nitrogen fixation
Why can’t most living things use nitrogen gas N2 directly from the atmosphere?
Because N2 is very stable and needs to be converted into usable forms (like nitrates or ammonium) by bacteria.
How does excess fertilizer use affect the nitrogen cycle?
It adds too much nitrogen to ecosystems, causing water pollution and dead zones.
How do legumes like beans and peas help the nitrogen cycle?
They host nitrogen-fixing bacteria in their roots that convert N₂ into usable forms.