Nitrogen Cycle The nitrogen cycle is the biogeochemical
Nitrogen Cycle • The nitrogen cycle is the biogeochemical cycle by which nitrogen is exchanged between the biosphere and living organisms. • The Earth's atmosphere is about 78% nitrogen; however, it is in the form of nitrogen gas and is unusable by most living organisms. • Nitrogen is essential for many biological processes; and is crucial for any life here on Earth. – Nitrogen helps build our proteins!
Nitrogen Cycle • Important Vocabulary – Legumes – Root Nodules – Nitrogen-Fixing Bacteria
Nitrogen Cycle • Nitrogen in the atmosphere is unusable to plants and animals. • In order for nitrogen gas to be usable, it needs to be “FIXED. ” – Nitrogen-fixing bacteria create usable forms. – Lightning also “fixes” atmospheric nitrogen.
Nitrogen-Fixing Bacteria • Without Nitrogen-fixing bacteria, there would not be enough usable nitrogen available to living organisms. – Nitrogen-fixing bacteria “fix, ” or change the nitrogen gas from the atmosphere into a usable form for living organisms.
Nitrogen-Fixing Bacteria • Nitrogen-fixing bacteria live on the root nodules of legumes. – Legume plants include: beans, peas, and clover • The legumes provide habitat for the bacteria while the bacteria provide nitrogen to the plant.
Human Impacts on the Nitrogen Cycle • Increased global concentrations of nitrous oxide (N 2 O) creates acid rain. • Increased use of fertilizers increases nitrogen runoff into our waterways and contributes to eutrophication.
REMEMBER THIS!!! • Atmospheric nitrogen (gas) is unusable by most living organisms. • Nitrogen-fixing bacteria provide most of the usable nitrogen. • Nitrogen-fixing bacteria are found on the root nodules of legumes.
Nitrogen Cycle Summary • Now you have learned about the nitrogen cycle, check out the: Nitrogen Cycle Animation
Questions? ? ? Question 8: Where is most nitrogen found? Question 9: Where does usable nitrogen come from? Question 10: What type of relationship exists between nitrogen-fixing bacteria and legumes?
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